6510A 8bit CPU, 1.02 MHz (NTSC) or 0.98 MHz (PAL), Compatible with 6502

  64Kbytes RAM (used for both work RAM and video RAM)
  16Kbytes KERNAL/BASIC ROM
  4Kbytes Character ROM (156 unique chars & many duplicated/inverted chars)
  1024x4bit Color RAM

  40x25 Character Text mode, or 320x200 (or 160x200) Pixels Bitmap mode
  40x25 Color attributes used for both Text and Bitmap modes
  High resolution allows two colors (out of 16) per 8x8 tile
  Low resolution allows four colors (out of 16) per 4x8 tile
  8 Sprites (each HiRes 24x21 one color, or LowRes 12x21 three colors)
  Horizontal and vertical sprite magnification (normal and double size)
  Sprite-to-Sprite and Sprite-to-Background collision detection

  3 independent tone generators - each with 9 octaves
  Each voice includes programmable ADSR generator (Attack, Decay,
  Sustain, Release) and control of sawtooth, triangle, square,
  variable pulse and noise waveforms
  Full filtering capabilities with low, high and band pass filters
  External sound input

  66 Keys, including not more than two (2) cursor keys

  User port
  Serial port (for Printer or Disk drive)
  ROM cartridge port
  2 Joystick/paddle ports
  2 Video ports (Monitor or TV)
  C1530 Cassette drive interface port (aka Datasette)

  External Supply, +5V DC and 9V AC(!).

  0000      MOS 6510 CPU On-Chip I/O Port Direction
  0001      MOS 6510 CPU On-Chip I/O Port Data - Memory and Datasette

  D000      Sprite 0 X Pos
  D001      Sprite 0 Y Pos
  D002      Sprite 1 X Pos
  D003      Sprite 1 Y Pos
  D004      Sprite 2 X Pos
  D005      Sprite 2 Y Pos
  D006      Sprite 3 X Pos
  D007      Sprite 3 Y Pos
  D008      Sprite 4 X Pos
  D009      Sprite 4 Y Pos
  D00A      Sprite 5 X Pos
  D00B      Sprite 5 Y Pos
  D00C      Sprite 6 X Pos
  D00D      Sprite 6 Y Pos
  D00E      Sprite 7 X Pos
  D00F      Sprite 7 Y Pos
  D010      Sprites 0-7 X Pos (msb of X coord.)
  D011      VIC Control Register (1)
  D012      Read Raster / Write Raster Value for Compare IRQ
  D013      Lightpen Latch X Pos
  D014      Lightpen Latch Y Pos
  D015      Sprite display Enable: 1 = Enable
  D016      VIC Control Register (2)
  D017      Sprites 0-7 Expand 2x Vertical (Y)
  D018      VIC Memory Control Register
  D019      VIC Interrupt Flag Register
  D01A      IRQ Mask Register: 1 = Interrupt Enabled
  D01B      Sprite to Background Display Priority
  D01C      Sprites 0-7 Multi-Color Mode Select
  D01D      Sprites 0-7 Expand 2x Horizontal (X)
  D01E      Sprite to Sprite Collision Detect
  D01F      Sprite to Background Collision Detect
  D020      Border Color
  D021      Background Color 0
  D022      Background Color 1
  D023      Background Color 2
  D024      Background Color 3
  D025      Sprite Multi-Color Register 0
  D026      Sprite Multi-Color Register 1
  D027      Sprite 0 Color
  D028      Sprite 1 Color
  D029      Sprite 2 Color
  D02A      Sprite 3 Color
  D02B      Sprite 4 Color
  D02C      Sprite 5 Color
  D02D      Sprite 6 Color
  D02E      Sprite 7 Color
  D02F-D03F Not used (always FFh)
  D040-D3FF Mirrors of above VIC registers (repeated each 40h bytes)

  D400      Voice 1: Frequency Control - Low-Byte
  D401      Voice 1: Frequency Control - High-Byte
  D402      Voice 1: Pulse Waveform Width - Low-Byte
  D403      Voice 1: Pulse Waveform Width - High-Nybble
  D404      Voice 1: Control Register
  D405      Envelope Generator 1: Attack / Decay Cycle Control
  D406      Envelope Generator 1: Sustain / Release Cycle Control
  D407      Voice 2: Frequency Control - Low-Byte
  D408      Voice 2: Frequency Control - High-Byte
  D409      Voice 2: Pulse Waveform Width - Low-Byte
  D40A      Voice 2: Pulse Waveform Width - High-Nybble
  D40B      Voice 2: Control Register
  D40C      Envelope Generator 2: Attack / Decay Cycle Control
  D40D      Envelope Generator 2: Sustain / Release Cycle Control
  D40E      Voice 3: Frequency Control - Low-Byte
  D40F      Voice 3: Frequency Control - High-Byte
  D410      Voice 3: Pulse Waveform Width - Low-Byte
  D411      Voice 3: Pulse Waveform Width - High-Nybble
  D412      Voice 3: Control Register
  D413      Envelope Generator 3: Attack / Decay Cycle Control
  D414      Envelope Generator 3: Sustain / Release Cycle Control
  D415      Filter Cutoff Frequency: Low-Nybble (Bits 2-0)
  D416      Filter Cutoff Frequency: High-Byte
  D417      Filter Resonance Control / Voice Input Control
  D418      Select Filter Mode and Volume
  D419      Analog/Digital Converter Game Paddle 1 (0-255)
  D41A      Analog/Digital Converter Game Paddle 2 (0-255)
  D41B      Oscillator 3 Random Number Generator
  D41C      Envelope Generator 3 Output
  D41D-D41F Not used (always 00h)
  D420-D7FF Mirrors of above SID registers (repeated each 20h bytes)

  D800-DBFF Color RAM (1000 Nybbles, plus 24 unused Nybbles)

  DC00      Data Port A (Keyboard, Joystick, Paddles): Game Port 2
  DC01      Data Port B (Keyboard, Joystick, Paddles, Lightpen): Game Port 1
  DC02      Data Direction Register - Port A
  DC03      Data Direction Register - Port B
  DC04      Timer A: Low-Byte
  DC05      Timer A: High-Byte
  DC06      Timer B: Low-Byte
  DC07      Timer B: High-Byte
  DC08      Time-of-Day Clock: 1/10 Seconds
  DC09      Time-of-Day Clock: Seconds
  DC0A      Time-of-Day Clock: Minutes
  DC0B      Time-of-Day Clock: Hours + AM/PM Flag (Bit 7)
  DC0C      Synchronous Serial I/O Data Buffer
  DC0D      CIA Interrupt Control Register (Read IRQs/Write Mask)
  DC0E      CIA Control Register A
  DC0F      CIA Control Register B
  DC10-DCFF Mirrors of above CIA1 registers (repeated each 10h bytes)

  DD00      Data Port A (Serial Bus, RS-232, VIC Memory Control)
  DD01      Data Port B (User Port, RS-232)
  DD02      Data Direction Register - Port A
  DD03      Data Direction Register - Port B
  DD04      Timer A: Low-Byte
  DD05      Timer A: High-Byte
  DD06      Timer B: Low-Byte
  DD07      Timer B: High-Byte
  DD08      Time-of-Day Clock: 1/10 Seconds
  DD09      Time-of-Day Clock: Seconds
  DD0A      Time-of-Day Clock: Minutes
  DD0B      Time-of-Day Clock: Hours + AM/PM Flag (Bit 7)
  DD0C      Synchronous Serial I/O Data Buffer
  DD0D      CIA Interrupt Control Register (Read NMIs/Write Mask)
  DD0E      CIA Control Register A
  DD0F      CIA Control Register B
  DD10-DDFF Mirrors of above CIA2 registers (repeated each 10h bytes)

  DE00-DEFF Reserved for Future I/O Expansion
  DF00-DFFF Reserved for Future I/O Expansion

  DE00-DEFF   Open I/O slot #1 (CP/M Enable)             256 Bytes
  DF00-DFFF   Open I/O slot #2 (Disk)                    256 Bytes

  Expansion Port <-- /IRQ-pin
  VIC <-- Lightpen Trigger
  VIC <-- Sprite to Sprite Collision
  VIC <-- Sprite to Background Collision
  VIC <-- Raster Compare Match
  CIA #1 <-- Timer A Interrupt
  CIA #1 <-- Timer B Interrupt
  CIA #1 <-- TOD Alarm Interrupt
  CIA #1 <-- Serial Port Interrupt
  CIA #1 <-- FLAG <-- Cassette Read
  CIA #1 <-- FLAG <-- Serial Bus SRQ

  Expansion Port <-- /NMI-pin
  Memory Controller <-- Trigger/Capaciator <-- Keyboard RESTORE-key
  CIA #2 <-- Timer A Interrupt
  CIA #2 <-- Timer B Interrupt
  CIA #2 <-- TOD Alarm Interrupt
  CIA #2 <-- Serial Port Interrupt
  CIA #2 <-- FLAG <-- User Port <-- Custom Hardware connected to Pin B
  CIA #2 <-- FLAG <-- User Port <-- RS-232 Adapter: Received Data Input
  CIA #2 <-- FLAG <-- User Port <-- Centronics Printer Adaper: Busy

  probably possible to "disable" the RESTORE-key by
  a not-acknowledged CIA interrupt signal ???

  Bit  Expl.
  0-7  Direction for Bit 0-7 of Port 0001h  (0=Input, 1=Output)

  Bit  Expl.
  0    /LORAM Signal (*)        (0=RAM, 1=BASIC ROM at A000-BFFF)
  1    /HIRAM Signal (*)        (0=RAM, 1=Kernal ROM at E000-FFFF)
  2    /CHAREN Signal (*)       (0=Character ROM, 1=I/O at D000-DFFF)
  3    Cassette Data Output     (Pulse)
  4    Cassette Switch Sense    (0=Switch Opened, 1=Switch Closed)
                                (0=play button down)
  5    Cassette Motor Control   (0=Motor On, 1=Motor Off)
  6-7  Not used

     Normal Operation   8K Expansion            16K Expansion
 Val /game=/exrom=high  /game=high,/exrom=low   /game=low,/exrom=low
  0  RAM                RAM                     IO/C,KERNAL
  1  IO/C               IO/C                    IO/RAM
  2  IO/C,KERNAL        IO/C,KERNAL             IO/C,KERNAL,ROMH
  3  IO/C,KERNAL,BASIC  IO/C,KERNAL,BASIC,ROML  IO/C,KERNAL,ROMH,ROML

  Addr  Bytes  Content
  0000  2      IO                   ;CPU On-chip I/O ports (no RAM here)
  0002  254    RAM                  ;BIOS system data
  0100  256    RAM                  ;CPU Stack
  0200  1.5K   RAM                  ;BIOS system data
  0800  30K    RAM                  ;Normal BASIC Program space
  8000  8K     RAM or ROML          ;Optional Cartridge ROML space
  A000  8K     RAM or BASIC or ROMH ;BASIC ROM, or ROMH space
  C000  4K     RAM                  ;RAM only
  D000  4K     RAM or IO or CHAR    ;I/O Ports+Colour RAM or CHAR ROM
  E000  8K     RAM or KERNAL        ;KERNAL ROM

  8000h-8001h Cold Start Vector
  8002h-8003h Warm Start Vector
  8004h-8008h ASCII ID Code "CBM80" with Bit7 set in the first 3 letters

  E000-FFFF=ROMH, 8000-9FFF=ROML, D000-DFFF=IO, 0000-0FFF=RAM, other=N/A

  7 - unused (Flash 8: 0=8MHz/1=1MHz)
  6 - unused (C128: ASCII/DIN sense/switch (1=ASCII/0=DIN))

  Bit  Name  Expl.
  7    RC8   Raster Compare Bit 8       (See below, Port D012h)
  6    ECM   Extended Color Text Mode   (0=Normal, 1=Extended)
  5    BMM   Bitmap Mode                (0=Text, 1=Bitmap)
  4    DEN   Display Enable             (0=Blank/Border Color, 1=Enable BG/MOB)
  3    RSEL  Row Select Display Height  (0=24 Rows, 1=25 Rows)
  0-2  Y0-2  Smooth Scroll Y Position   (0-7)

  Bit  Name  Expl.
  6-7  -     Unused
  5    RES   ALWAYS SET THIS BIT TO 0 !   ---  Huh, what/why ???
  4    MCM   Multi-Color Mode             (0=Disable, 1=Enable)
  3    CSEL  Column Select Display Width  (0=38 Columns, 1=40 Columns)
  0-2  X0-2  Smooth Scroll to X Position  (0-7)

  Bit  Name  Expl.
  0-7  RC0-7 Raster Compare/Scanline

  Bit  Name  Expl.
  4-7  VM#   Video Matrix Base Address Bit 13-10
  1-3  CB#   Character Dot-Data Base Address Bit 13-11
  0    -     Not used

  1000h or 9000h  -->  1st half of Character ROM (D000h)
  1800h or 9800h  -->  2nd half of Character ROM (D800h)

  Bit  Name  Expl.
  7    IRQ   Set on Any Enabled VIC IRQ Condition       (0=None, 1=IRQ)
  4-6  -     Not used
  3    ILP   Lightpen Triggered IRQ Flag                (0=None, 1=IRQ)
  2    IMMC  Sprite to Sprite Collision IRQ Flag        (0=None, 1=IRQ)
  1    IMBC  Sprite to Background Collision IRQ Flag    (0=None, 1=IRQ)
  0    IRST  Raster Compare IRQ Flag                    (0=None, 1=IRQ)

  Bit  Name  Expl.
  4-7  -     Not used
  3    ELP   Lightpen Triggered              (0=Disable, 1=Enable)
  2    EMMC  Sprite to Sprite Collision      (0=Disable, 1=Enable)
  1    EMBC  Sprite to Background Collision  (0=Disable, 1=Enable)
  0    ERST  Raster Compare                  (0=Disable, 1=Enable)

  Bit  Name  Expl.
  0-7  M#E   Sprite 0-7 Enable        (0=Hidden, 1=Display)

  Bit  Name  Expl.
  0-7  M#YE  Sprite 0-7 Expand Y      (0=Normal, 1=Magnified by two)

  Bit  Name  Expl.
  0-7  M#DP  Sprite 0-7 Priority   (0=Above BG, 1=Behind BG)  OR VICE-VERSA ???

  Bit  Name  Expl.
  0-7  M#MC  Sprite 0-7 Multi Color   (0=Normal, 1=Multi Color)

  Bit  Name  Expl.
  0-7  M#XE  Sprite 0-7 Expand X      (0=Normal, 1=Magnified by two)

  Bit  Name  Expl.
  0-7  M#M   Sprite 0-7 Collision Flag  (0=Normal, 1=Collision)

  Bit  Name  Expl.
  0-7  M#D   Sprite 0-7 Collision Flag  (0=Normal, 1=Collision)

  0   Black        8   Orange
  1   White        9   Brown
  2   Red          10  Light red
  3   Cyan         11  Dark grey
  4   Purple       12  Medium grey
  5   Green        13  Light green
  6   Blue         14  Light blue
  7   Yellow       15  Light grey

  Sprite  0     1     2     3     4     5     6     7
  Port    D027  D028  D029  D02A  D02B  D02C  D02D  D02E

  BMM ECM MCM  Mode Name
  0   0   0    Standard Character Mode
  0   0   1    Multi-Color Character Mode
  0   1   0    Extended Color Character Mode
  0   1   1    Reserved
  1   0   0    Standard Bitmap Mode
  1   0   1    Multi-Color Bitmap Mode
  1   1   0    Reserved
  1   1   1    Reserved

  2048 Bytes    Character Data         (256 tiles)
  1000 Bytes    Video Matrix Data      (40x25 tile numbers)
  1000 Nybbles  Color RAM              (40x25 color attributes)

  8000 Bytes    Character Data         (40x25 tiles) - Addressed by CB13
  1000 Bytes    Video Matrix Data      (40x25 color attributes)
  1000 Nybbles  Color RAM              (40x25 color attributes)

  0   BG color 0 (Port D021h)          (0-15)
  1   Color as selected by Nybble      (0-15)

  0   BG color 0 (Port D021h)          (0-15)
  1   Color as selected by Nybble LSBs (0-7)

  0   BG color 0 (Port D021h)          (0-15)
  1   BG color 1 (Port D022h)          (0-15)
  2   BG color 2 (Port D023h)          (0-15)
  3   Color as selected by Nybble LSBs (0-7)

  0   BG Color 0-3 (Port D021h-D024h)  (0-15)
  1   Color as selected by Nybble      (0-15)

  0   LSBs of video matrix entry       (0-15)
  1   MSBs of video matrix entry       (0-15)

  0   BG Color 0 (Port D021h)          (0-15)
  1   MSBs of video matrix entry       (0-15)
  2   LSBs of video matrix entry       (0-15)
  3   Video Matrix Color Nybble        (0-15)

  0   Transparent                       (-)
  1   Sprite Color (Port D027h-D02Eh)   (0-15)

  0   Transparent                       (-)
  1   Sprite Multi Color 0 (Port D025h) (0-15)
  2   Sprite Color (Port D027h-D02Eh)   (0-15)
  3   Sprite Multi Color 1 (Port D026h) (0-15)

  CHR  ASCII CHARSET     ROM CHARSET 1     ROM CHARSET 2
  0Xh  \\\\\\\\\\\\\\\\  @ABCDEFGHIJKLMNO  @abcdefghijklmno
  1Xh  \\\\\\\\\\\\\\\\  PQRSTUVWXYZ[\]^\  pqrstuvwxyz[\]^\
  2Xh   !"#$%&'()*+,-./   !"#$%&'()*+,-./   !"#$%&'()*+,-./
  3Xh  0123456789:;<=>?  0123456789:;<=>?  0123456789:;<=>?
  4Xh  @ABCDEFGHIJKLMNO  \\\\\\\\\\\\\\\\  \ABCDEFGHIJKLMNO
  5Xh  PQRSTUVWXYZ[\]^\  \\\\\\\\\\\\\\\\  PQRSTUVWXYZ\\\\\
  6Xh  \\\\\\\\\\\\\\\\  \\\\\\\\\\\\\\\\  \\\\\\\\\\\\\\\\
  7Xh  \\\\\\\\\\\\\\\\  \\\\\\\\\\\\\\\\  \\\\\\\\\\\\\\\\

  SET  CPU Address   VIC Addresses
  1    D000h-D7FFh   1000h-17FFh or 9000h-97FFh
  2    D800h-DFFFh   1800h-1FFFh or 9800h-9FFFh

  YY_POS     3bit  internal counter (vertical position in current char row)
  PIC_ON     1bit  internal flag (picture output enable)
  BORDER     1bit
  CHAR_ADDR 10bit  internal screen matrix address (of current char row)
  ROW_BUF  40x12bit  internal buffer for 8bit tile numbers & 4bit colors

  Item          NTSC            PAL
  Oscillator    14.318181 MHz   17.734472 MHz
  Divider       Osc/14          Osc/18
  System Clock  1.022727 MHz    0.985248 MHz
  Frame Rate    ca. 60Hz        ca. 50Hz
  Scanlines     263             312
  Clks/Line     65              63

  NTSC: 6567R5 6A:         64 cycles/line x 262 lines.
  NTSC: 6567R8 and newer:  65 cycles/line x 263 lines.

  Bit  Expl.
  7    Select Random Noise Waveform, 1 = On
  6    Select Pulse Waveform, 1 = On
  5    Select Sawtooth Waveform, 1 = On
  4    Select Triangle Waveform, 1 = On
  3    Test Bit: 1 = Disable Oscillator 1/1/1
        - That is "1/1/1" for all voicechannels ???
  2    Ring Modulate Osc. 1/2/3 with Osc. 3/1/2 Output, 1 = On
  1    Synchronize Osc. 1/2/3 with Osc. 3/1/2 Frequency, 1 = On
  0    Gate Bit: 1 = Start Att,Dec,Sus, 0 = Start Release

  Bit  Expl.
  4-7  Select Attack Cycle Duration:  0-15
  0-3  Select Decay Cycle Duration:   0-15

  Bit  Expl.
  4-7  Select Sustain Cycle Duration: 0-15
  0-3  Select Release Cycle Duration: 0-15

  ----- Control Registers -----

  Bit  Expl.
  4-7  Select Filter Resonance: 0-15
  3    Filter External Input: 1 = Yes, 0 = No
  2    Filter Voice 3 Output: 1 = Yes, 0 = No
  1    Filter Voice 2 Output: 1 = Yes, 0 = No
  0    Filter Voice 1 Output: 1 = Yes, 0 = No

  Bit  Expl.
  7    Cut-Off Voice 3 Output: 1 = Off, 0 = On
  6    Select Filter High-Pass Mode: 1 = On
  5    Select Filter Band-Pass Mode: 1 = On
  4    Select Filter Low-Pass Mode: 1 = On
  0-3  Select Output Volume: 0-15

  Bit  Dir. Expl.
  7-0  Out  Select Keyboard Column 7-0    (0=Select, 1=Not select)
  7-6  Out  Select Analog Paddle      (01b=Paddle 1, 10b=Paddle 2) ???
  5    -    Used for Keyboard only              (See above, Bit 7-0)
  4    In   Joystick 2 Fire                     (0=Pressed, 1=Released)
  3    In   Joystick 2 Right, Paddle 2 Y-Button (0=Moved/Pressed, 1=Released)
  2    In   Joystick 2 Left, Paddle 2 X-Button  (0=Moved/Pressed, 1=Released)
  1    In   Joystick 2 Down                     (0=Moved, 1=Released)
  0    In   Joystick 2 Up                       (0=Moved, 1=Released)

  Bit  Dir. Expl.
  7-0  In   Keyboard Row 7-0 Input              (0=Pressed, 1=Released)
  7    Out  Timer B Toggle/Pulse Output         (Output from Timer B)
  6    Out  Timer A Toggle/Pulse Output         (Output from Timer A)
  5    In   Used for Keyboard only              (See above, Bit 7-0)
  4    In   Joystick 1 Fire (or Lightpen)       (0=Pressed, 1=Released)
  3    In   Joystick 1 Right, Paddle 1 Y-Button (0=Moved/Pressed, 1=Released)
  2    In   Joystick 1 Left, Paddle 1 X-Button  (0=Moved/Pressed, 1=Released)
  1    In   Joystick 1 Down                     (0=Moved, 1=Released)
  0    In   Joystick 1 Up                       (0=Moved, 1=Released)

  1) Read joysticks
  2) Read keyboard columns
  3) Read joysticks again

  1st Joystick = Joystick A = JOY B = CIA Port A (DC00h) = Port 2
  2nd Joystick = Joystick 1 = JOY A = CIA Port B (DC01h) = Port 1

  Bit  Dir. Expl.
  7         Serial Bus Data Input
  6         Serial Bus Clock Pulse Input
  5         Serial Bus Data Output
  4         Serial Bus Clock Pulse Output
  3         Serial Bus ATN Signal Output
  2         User / RS-232 Data Output / CNTR "/Strobe"
  1-0  Out  VIC Memory Bank XOR 3  (Default=3, see VIC Port D018h)

  Bit  Dir. Expl.
  7    Out  Timer B Toggle/Pulse Output         (Output from Timer B)
  6    Out  Timer A Toggle/Pulse Output         (Output from Timer A)
  7         User / RS-232 Data Set Ready
  6         User / RS-232 Clear to Send
  5         User
  4         User / RS-232 Carrier Detect
  3         User / RS-232 Ring Indicator
  2         User / RS-232 Data Terminal Ready
  1         User / RS-232 Request to Send
  0         User / RS-232 Received Data

  00            Keyboard
  01            Datassette(TM)
  02            RS-232C device
  03            CRT display
  04            Serial bus printer
  08            Serial bus disk drive unit 1
  09            Serial bus disk drive unit 2
  0A            Serial bus disk drive unit 3
  0B            Serial bus disk drive unit 4

  Bit  Expl.
  7-0  Data Direction for Port A/B Bits 7-0 each  (0=Input, 1=Output)

        Is that eventually 00-11 or actually 12,01-11 Hours ???

  Bit  Expl.
  7    Any enabled interrupt (0=None, 1=Yes) / Set-Clear Flag (0=Clear, 1=Set)
  6-5  Not used                         (always read out as zero)
  4    FLAG External IRQ/NMI Input,
         CIA #1 - IRQ - Cassette Read, Serial Bus SRQ Input
         CIA #2 - NMI - User, RS-232 Received Data Input, CNTR Busy
  3    Serial Port Interrupt
  2    Time-of-Day Clock Alarm Interrupt
  1    Timer B Interrupt
  0    Timer A Interrupt

  Bit  Expl.
  7    Time-of-Day Clock Frequency      (0=9VAC/60Hz, 1=9VAC/50Hz)
  6    Serial Port I/O Mode Output      (0=Input, 1=Output)
  5    Timer A Counts                   (0=System 02 Clock, 1=CNT Signals)
  4    Timer A Force Load               (0=No, 1=Yes)
  3    Timer A Run Mode                 (0=Continuous, 1=One-Shot)
  2    Timer A Output-to-Port-B Mode    (0=Pulse, 1=Toggle)
  1    Timer A Output-to-Port-B Enable  (0=Disable, 1=Enable)
  0    Timer A Start/Stop               (0=Stop, 1=Start)

  Bit  Expl.
  7    Time-of-Day Write Mode           (0=Set Clock, 1=Set Alarm)
  6-5  Timer B Mode Select:
         0 = Count System 02 Clock Pulses
         1 = Count Positive CNT Transitions
         2 = Count Timer A Underflow Pulses
         3 = Count Timer A Underflows While CNT Positive
  4-0  Same as for above Timer A, but for Timer B respectively.

  CPU: 6502A, 1.02 MHz (NTSC), 1.11 MHz (PAL)
  ROM: 16K Basic/Kernal ROM, 4K Character ROM (2 sets of 256 characters)
  RAM: 5K RAM (expandable to 40K RAM max), 1Kx4bit Color RAM
  Video: 22x23 tiles, 176x184 pix (1bit HiRes), or 88x184 pix (2bit MultiColor)
  Color: 16 Color Palettte, 2 or 4 Colors (Hires/Multi), 1 unique color/tile
  Sound: 3x Square Wave, 1x Noise, 1x Volume (shared for all 4 channels)
  Ports: One Joystick port, User Port, Expansion Port, Serial Port, Cassette
  Keyboard: Matrix with 8x8 Keys, plus Restore Key

  Addr. Size Expl.
  0000h  1K  RAM (BIOS,KERNAL,STACK)
  0400h  3K  Expansion RAM
  1000h  4K  RAM (3.5K BASIC/USER, 0.5K Screen RAM)
  2000h 24K  Expansion RAM (or ROM)
  8000h  1K  Character ROM Uppercase and all Symbols (Normal)
  8400h  1K  Character ROM Uppercase and all Symbols (Reversed)
  8800h  1K  Character ROM Upper/lowercase and some Symbols (Normal)
  8C00h  1K  Character ROM Upper/lowercase and some Symbols (Reversed)
  9000h      I/O Area (VIC Chip, VIA1, VIA2)
  9400h      Color RAM (1024x4bit)
  9800h      Expansion I/O Area 2
  9C00h      Expansion I/O Area 3
  A000h  8K  Expansion ROM (or RAM)
  C000h  8K  BASIC ROM
  E000h  8K  KERNAL ROM

  Basic RAM must be located in a continous memory block.
  Screen RAM must be located in built-in 4K RAM.
  Color RAM address bit9 must match Screen RAM address bit9.

  Expansion  Total RAM  Basic RAM    Screen RAM   Color RAM    Basic Space
  None       5K         1000h-1DFFh  1E00h-1FFFh  9600h-97FFh  3.5K
  3K         8K         0400h-1DFFh  1E00h-1FFFh  9600h-97FFh  6.5K
  8K..35K    13K..40K   1200h-7FFFh  1000h-11FFh  9400h-95FFh  11.5K..27.5K

  A000h-A001h Cold Start Vector (invoked after RESET with S=FFh, D=0, I=1)
  A002h-A003h Warm Start Vector
  A004h-A008h ASCII ID Code "A0CBM" with Bit7 set in the last 3 letters

  9000h  Horizontal Screen Origin, and Interlace
  9001h  Vertical Screen Origin
  9002h  Horizontal Screen Size, and Screen Base
  9003h  Vertical Screen Size, Raster, and Character Size
  9004h  Raster Value
  9005h  Video Memory Base Addresses
  9006h  Lightpen Horizontal
  9007h  Lightpen Vertical
  9008h  Paddle X Position
  9009h  Paddle Y Position
  900Ah  Voice 1 Square/Bass
  900Bh  Voice 2 Square/Alto
  900Ch  Voice 3 Square/Soprano
  900Dh  Voice 4 Noise
  900Eh  Sound Volume, and Auxiliary Color
  900Fh  Screen Color, Border Color, and Reverse Mode

  91x0h  Input/Output Register B (IRB/ORB)
  91x1h  Input/Output Register A (IRA/ORA)
  91x2h  Data Direction Register B (DDRB)
  91x3h  Data Direction Register A (DDRA)
  91x4h  T1 Low-order Counter/Latch (T1C_L)
  91x5h  T1 High-order Counter/Latch (T1C_H)
  91x6h  T1 Low-order Latch (T1L_L)
  91x7h  T1 High-order Latch (T1L_H)
  91x8h  T2 Low-Order Latch/Counter (T2C_L)
  91x9h  T2 High-Order Counter (T2C_H)
  91xAh  Shift Register (SR)
  91xBh  Auxiliary Control Register (ACR)
  91xCh  Peripheral Control Register (PCR)
  91xDh  Interrupt Flag Register (IFR) (Request/Acknowledge)
  91xEh  Interrupt Enable Register (IER) (Enable/Disable)
  91xFh  Input/Output Register A' (IRA'/ORA')

  Bit7   Interlace mode   (0=Off/Normal, 1=On) (NTSC Only) (PAL: No Effect)
  Bit6-0 Left Border width (in FOUR pixel steps)

  Bit0-7 Upper Border Height (in TWO pixel steps)

  Bit7   Screen Base A9          (1 = +0200h) (see Port 9005h), and
         Color RAM Base A9       (0=9400h, 1=9600h)
  Bit6-0 Number of video columns (Default = 22 columns; 176 pixels)

  Bit7   Bit 0 of Raster value (Bits 8-1 are in Port 9004h)
  Bit6-1 Number of video rows  (Default is 23 rows; 184 pixels)
  Bit0   Character size (0=Normal 8x8, 1=Large 8x16)

  Bit7-0 Bits 8-1 of Raster value (Bit 0 is in Port 9004h)

  ([9004h]-[9001h]) * 2 + [9003h].Bit7

  Bit Expl.
  7   Screen Base A13    (0=ROM, 1=RAM) (Must be RAM, obviously)
  6   Screen Base A12    (1 = +1000h)
  5   Screen Base A11    (1 = +0800h)
  4   Screen Base A10    (1 = +0400h)
  -   Screen Base A9     (1 = +0200h) (A9 defined in Port 9002h)
  3   Character Base A13 (0=ROM, 1=RAM)
  2   Character Base A12 (1 = +1000h)
  1   Character Base A11 (1 = +0800h)
  0   Character Base A10 (1 = +0400h)

  CPU          VIC               Content
  0000h-03FFh  (see note)        1K Internal RAM
  0400h-0FFFh  No                3K Expansion RAM
  1000h-1FFFh  Characters/Screen 4K Internal RAM
  8000h-8FFFh  Characters        4K Character ROM
  9000h-9FFFh  No                4K I/O Area

  Bit7-0 Light pen position in pixels (00h=upper/left)

  Bit7-0 Paddle Input (0-FFh) (A/D converted variable resistance)

  Bit 7   Sound Enable    (0=Off, 1=On)
  Bit 6-0 Sound Frequency (0-127); F = Baseclock / (127-X)

  Bit 7-4  Auxiliary color (0-15) (Color 3 for Multi-Color tiles)
  Bit 3-0  Volume for all Sound channels (0=Off, 15=Loudest)

  Bit 7-4 Background/Screen Color (0-15) (Color 0 of all tiles)
  Bit 3   Character Reverse Mode  (0=Inverted, 1=Normal)
  Bit 2-0 Border Color            (0-7) (also Color 1 of Multi-Color tiles)

  Bit7-4  Not used          (returns garbage when reading)
  Bit3    Resolution/Depth  (0=Hi-Res 8x8, 2 color, 1=Multi-Color 4x8, 4 color)
  Bit2-0  Character Color   (0-7) (Indepent color for each tile)

  Hi-Res   Multi-Color  Color Source
  Color 0  Color 0      Screen color (0-15)    (Port 900Fh, Bit4-7)
  -        Color 1      Border color (0-7)     (Port 900Fh, Bit0-2)
  Color 1  Color 2      Character color (0-7)  (Color RAM)
  -        Color 3      Auxiliary color (0-15) (Port 900Eh, Bit4-7)

  0 Black               8 Orange
  1 White               9 Light Orange
  2 Red                10 Light Red (Pink)
  3 Cyan (Green+Blue)  11 Light Cyan
  4 Purple (Red+Blue)  12 Light Purple
  5 Green              13 Light Green
  6 Blue               14 Light Blue
  7 Yellow (Green+Red) 15 Light Yellow

  Type          NTSC 60Hz       PAL 50Hz
  Oscillator    14.318181 MHz   17.734472 MHz
  Divider       Osc/14          Osc/16
  System Clock  1.022727 MHz    1.108405 MHz
  Visible       ???x???         ???x???
  Scanlines     261             312
  Clks/Line     65 clks         71 clks
  Clks/Char     2 clks          2 clks

  Bit  Pin(s)       Purpose/Example
  PB0  USR.C        RS232 Received data (Sin)          (0=Low)
  PB1  USR.D        RS232 Request to Send (RTS)        (0=Low)
  PB2  USR.E        RS232 Data terminal ready  (DTR)   (0=Low)
  PB3  USR.F        RS232 Ring indicator (RI)          (0=Low)
  PB4  USR.H        RS232 Received line signal (DCD)   (0=Low)
  PB5  USR.J        Not used with RS232                (0=Low)
  PB6  USR.K        RS232 Clear to send (CTS)          (0=Low)
  PB7  USR.L        RS232 Data set ready (DSR)         (0=Low)

  Bit  Pin(s)       Purpose/Example
  PA0  SIO.4        Serial CLK IN                  (0=Low)
  PA1  SIO.5        Serial DATA IN                 (0=Low)
  PA2  JOY.1/USR.4  Joy S0 Up    ;JOY S0,S1,S2,S4 controlled by VIA #1 Port A
  PA3  JOY.2/USR.5  Joy S1 Down  ;JOY S3: see VIA #2 Port B
  PA4  JOY.3/USR.6  Joy S2 Left/Paddle Switch X    (0=Low)
  PA5  JOY.6/USR.7  Joy S4 Fire/Lightpen           (0=Low)
  PA6  CAS.6/USR.8  Cassette switch sense          (0=Low)
  PA7  SIO.3/USR.9  Serial ATN out                 (1=Low) (Inverted)

  Item Pin(s)       Purpose/Example
  T1                Timer 1
  T2                Timer 2
  SHFT              Shift register
  CA1  KEYB         Restore key                    (0=Low=Pressed)
  CA2  CAS.3        Cassette motor control         (?=On)
  CB1  USR.B        Interrupt signal for received RS-232 data
  CB2  USR.M        Transmitted RS-232 data
  /INT CPU.6/EXP.W  CPU Non Maskable Interrupt (and Expansion Port) (NMI)

  Bit   Pin(s)      Purpose/Example
  PB0-7 COL.0-7     Keyboard Column scan           (0=Low)
  PB3   COL.3/CAS.5 Cassette write line            (0=Low)
  PB7   COL.7/JOY.4 Joy S3 Right/Paddle Switch Y   (0=Low)

  Bit   Pin(s)      Purpose/Example
  PA0-7 ROW.0-7     Keyboard Row scan              (0=Low)

  Item Pin(s)       Purpose/Example
  T1                Timer 1 (used for 60Hz Jiffy clock interrupt)
  T2                Timer 2
  SHFT              Shift register
  CA1  CAS.4        Cassette read line          (0=Low)
  CA2  SIO.4        Serial CLK OUT              (1=Low) (Inverted)
  CB1  SIO.1        Serial SRQ IN               (0=Low)
  CB2  SIO.5        Serial DATA OUT             (1=Low) (Inverted)
  /INT CPU.4/EXP.19 CPU Interrupt Request (and Expansion Port) (IRQ)

  Pin Control   Name  Purpose
  1   VIA1.PA2  JOY0  Up
  2   VIA1.PA3  JOY1  Down
  3   VIA1.PA4  JOY2  Left/Paddle Switch X
  4   VIA2.PB7  JOY3  Right/Paddle Switch Y
  5   VIC.POTY  POTY  Paddle Position Y
  6   VIA1.PA5  JOY4  Fire/Lightpen
  7   -         5V    +5V (max 100mA)
  8   -         GND   Ground
  9   VIC.POTX  POTX  Paddle Position X

  1  +5V REG (max 10mA)
  2  GND
  3  AUDIO
  4  VIDEO LOW  (VIC20: via 3.9uH & capacitor, VIC20CR: shortcut with Pin 5)
  5  VIDEO HIGH (direct output without loop/capacitor, otherwise same as Pin 4)

  1  SERIAL SRQ IN
  2  GND
  3  SERIAL ATN OUT
  4  SERIAL CLC IN/OUT
  5  SERIAL DATA IN/OUT
  6  /RESET (or N.C.)

  A-1  GND
  B-2  +5V
  C-3  CASSETTE MOTOR  (VIA1.CA2) (+9V)
  D-4  CASSETTE READ   (VIA2.CA1)
  E-5  CASSETTE WRITE  (VIA2.PB3)
  F-6  CASSETTE SWITCH (VIA1.PA6)

  1 GND  Ground                    A GND Ground
  2 5V   +5VDC max 100mA           B CB1 RS232 Interrupt for Sin
  3 /RES /RESET                    C PB0 RS232 Received data (Sin)
  4 PA2  JOY0 Up                   D PB1 RS232 Request to Send (RTS)
  5 PA3  JOY1 Down                 E PB2 RS232 Data terminal ready  (DTR)
  6 PA4  JOY2 Left/Paddle Switch X F PB3 RS232 Ring indicator (RI)
  7 PA5  JOY4 Fire/Lightpen        H PB4 RS232 Received line signal (DCD)
  8 PA6  Cassette switch sense     J PB5 Not used with RS232
  9 PA7  SERIAL ATN OUT            K PB6 RS232 Clear to send (CTS)
  10 9V  9VAC Phase 1 max 100mA    L PB7 RS232 Data set ready (DSR)
  11 9V  9VAC Phase 2 max 100mA    M CB2 RS232 Transmitted data (Sout)
  12 GND Ground                    N GND Ground

  Pin      Name    Description
  2-9      CD0-7   Data bus Bits 0-7
  B-S      CA0-13  Address bus Bits 0-13 (upper bits decoded in /IO,/RAM,/BLK)
  10-12    /BLK1-3 8K decoded RAM/ROM blocks 1,2,3 at 2000h,4000h,6000h
  13       /BLK5   8K decoded ROM block 5 at A000h
  14-16    /RAM1-3 1K decoded RAM blocks 1,2,3 at 0400h,0800h,0C00h
  T-U      /IO2-3  I/O blocks 2,3 (located at 9800h,9C00h) (eg. IEEE adapter)
  17       VR/W    Read/Write line from VIC chip (high-read, low-write)
  18       CR/W    Read/Write line from CPU chip (high-read, low-write)
  V        PHI2    Phase 2 system clock
  19       /IRQ    6502 Interrupt Request ("keyboard scan and system clock")
  W        /NMI    6502 Non Maskable Interrupt (WARMSTART, RUN/STOP-RESTORE)
  X        /RESET  6502 RESET pin
  21       +5V     Supply
  1,22,A,Z GND     System ground
  20       (NC)    Not connected
  Y        SNDIN   Not connected (VIC20), or Audio In (VIC20CR)

  1     N.C.
  2     COMP COLOR
  3     SYNC & LUMINANCE
  4     R/W
  5-16  DB11-0
  17,18 POTX,POTY
  19    SOUND OUT
  20    GND
  21-34 A0-13 (Note: A13 is gained from /BLK4 signal)
  35,36 P01,P02 Clock Out, NTSC: X/14 = 1.02MHz, PAL: X/16 = 1.11MHz
  37    LPEN
  38,39 X02,X01 Clock In, NTSC: 14318181Hz, PAL:17734472Hz
  40    VCC 5VDC

  CPU 7501/8501 - 6502 compatible with on-chip 7bit I/O Port
  16K DRAM (3FFEh bytes can be used) (shared as WRAM and VRAM)
  32K ROM (BASIC V3.5, separate KERNALs for PAL-B and NTSC-M)
  TED (Text Editing Device) for Video, Sound, Timers, Keyboard
  Four cursor keys (unfortunately arranged all in one row)

    Character graphics, high resolution graphics, Enhanced Colour Mode and
    reverse characters
    Multicolour graphics (4x8 character or graphics cells)
    Writable horizontal and vertical sync counters
    Horizontal raster position register
    Same chip for both NTSC-M and PAL-B
       1.NTSC:  14318181/16 Hz
         NTSC = 0.894886 MHz (single), or 1.789773 MHz (twice)
       2.PAL:   17734472/20 Hz
         PAL  = 0.886724 MHz (single), or 1.773447 MHz (twice)
    Double clock mode for faster operation

  0000h-0001h   I/O CPU 7501/8501 On-chip I/O Port
  0002h-7FFFh   RAM
  8000h-BFFFh   RAM or LO ROM (Basic, Function LO, Cart 1 LO, Cart 2 LO)
  C000h-FBFFh   RAM or HI ROM (Kernal, Function HI, Cart 1 HI, Cart 2 HI)
  FC00h-FCFFh   RAM or HI ROM (Kernal)
  FD00h-FF3Fh   I/O Area
  FF40h-FFFFh   RAM or HI ROM (Kernal, Function HI, Cart 1 HI, Cart 2 HI)

  D000h-D7FFh  256 non-inverted tiles

  FCF1h-FCF3h  Jump to interrupt routine for cartridge
  FCF4h-FCF6h  Jump to cartridge reenable routine
  FCF7h-FCF9h  Jump to long fetch routine
  FCFAh-FCFCh  Jump to long jump routine
  FCFDh-FCFFh  Jump to long interrupt routine

  0000h - CPU 7501/8501 On-Chip I/O Port Direction
  0001h - CPU 7501/8501 On-Chip I/O Port Data (Cassette, Serial, User Port)

  FD00h-FD0Fh - User Port RS232 Controller 6551A (Plus/4 Only - Not C16/C116)
  FD10h-FD1Fh - Cassette Sense / User Port 8bit Parallel I/O
  FD30h-FD3Fh - 6529B Keyboard Column Output Latch
  FDD0h-FDDFh - ROM Bank Latch

  FF00h - Timer 1 Counter/Reload LSB
  FF01h - Timer 1 Counter/Reload MSB
  FF02h - Timer 2 Counter LSB
  FF03h - Timer 2 Counter MSB
  FF04h - Timer 3 Counter LSB
  FF05h - Timer 3 Counter MSB
  FF06h - Video Control Register 1
  FF07h - Video Control Register 2
  FF08h - Keyboard / Joystick Latch
  FF09h - Interrupt request register
  FF0Ah - Interrupt mask register
  FF0Bh - Raster interrupt register
  FF0Ch - Hardware-cursor position MSB (2bit) (Bit7-2 unused)
  FF0Dh - Hardware-cursor position LSB (8bit)
  FF0Eh - Sound 1 Frequency LSB (8bit)
  FF0Fh - Sound 2 Frequency LSB (8bit)
  FF10h - Sound 1 (or 2 ?) Frequency MSB (2bit) (Bit7-2 unused)
  FF11h - Sound control register
  FF12h - Bitmap/Character Memory Control and Sound 2 Frequency MSB
  FF13h - System Clock and Character Memory Control
  FF14h - Screen/Color Memory Control
  FF15h - Background Color 0
  FF16h - Background Color 1
  FF17h - Background Color 2
  FF18h - Background Color 3
  FF19h - Border Color
  FF1Ah - Current Character Position MSB (2bit) (Bit7-2 unused)
  FF1Bh - Current Character Position LSB (8bit)
  FF1Ch - Current Scanline MSB (1bit) (Bit7-1 unused)
  FF1Dh - Current Scanline LSB (8bit)
  FF1Eh - Actual position of horizontal scanning. R/W!.
  FF1Fh - Flashing Counter and Character Scanline Index

  FF3Eh - CPU/Screen/Color ROM Enable
  FF3Fh - CPU/Screen/Color RAM Enable

  8000h-8002h  Entrypoint (started by JSR 8000h)
  8003h-8005h  Another Entrypoint, not used by BIOS (?)
  8006h        Desired Entry Time (00h=Never, 01h=Immediately, 02h..FFh=Later)
  8007h-8009h  ASCII ID "CBM"

  7-0  Keyboard Column 7-0 Selection     (0=Select, 1=Deselect)

  7-3  Not used
  2    Joystick 1         (0=Select, 1=Deselect)
  1    Joystick 2         (0=Select, 1=Deselect)
  0    Not used

  7-0  State of Row 7-0 for any selected columns (0=Pressed, 1=Released)
  7    Joystick 2 Fire    (0=Pressed, 1=Released)
  6    Joystick 1 Fire    (0=Pressed, 1=Released)
  3    Joystick 1/2 Right (0=Moved, 1=Released)
  2    Joystick 1/2 Left  (0=Moved, 1=Released)
  1    Joystick 1/2 Down  (0=Moved, 1=Released)
  0    Joystick 1/2 Up    (0=Moved, 1=Released)

  Bit Dir Expl.
  7   In  Serial Data In (and PLUS/4: Cas Sense) (0=Low, 1=High)
  6   In  Serial Clock In                        (0=Low, 1=High)
  5   -   Not used (no pin-out on 7501/8501)     (N/A)
  4   In  Cassette Read                          (0=Low, 1=High)
  3   Out Cassette Motor                         (0=9VDC, 1=Off) (Inverted)
  2   Out Serial ATN Out (and PLUS/4: User Port) (0=High, 1=Low) (Inverted)
  1   Out Serial Clock Out, Cassette Write       (0=High, 1=Low) (Inverted)
  0   Out Serial Data Out                        (0=High, 1=Low) (Inverted)

  7-0 User Port 6529B, 8bit Parallel I/O   (PLUS/4 Only)
  2   Cassette Sense In                    (C16 and C116 Only)

  reg=1024-(111860.781/frq[Hz]) (NTSC)
  reg=1024-(111840.45 /frq[Hz]) (PAL)

  Bit7    D/A mode. See below for more.
  Bit6    Sound #2 noise on/off. If You set both, the square will sound.
  Bit5    Sound #2 squarewave on/off.
  Bit4    Sound #1 squarewave on/off.
  Bit0-3  Volume. Maximum value is 8. //OR:// 0=Off, F=Highest

  Bit7  Set on Any-Enabled-IRQ Condition  (0=None, 1=IRQ)
  Bit6  Timer 3 Interrupt Request         (0=None, 1=IRQ / Acknowledge)
  Bit5  Unused
  Bit4  Timer 2 Interrupt Request         (0=None, 1=IRQ / Acknowledge)
  Bit3  Timer 1 Interrupt Request         (0=None, 1=IRQ / Acknowledge)
  Bit2  Lightpen Interrupt Request        (Not implemented?)
  Bit1  Raster Interrupt Request          (0=None, 1=IRQ / Acknowledge)
  Bit0  Unused

  Bit7  Unused
  Bit6  Timer 3 Interrupt        (0=Disable, 1=Enable)
  Bit5  Unused
  Bit4  Timer 2 Interrupt        (0=Disable, 1=Enable)
  Bit3  Timer 1 Interrupt        (0=Disable, 1=Enable)
  Bit2  Lightpen Interrupt       (Not implemented?)
  Bit1  Raster Interrupt         (0=Disable, 1=Enable)
  Bit0  High bit of Raster FF0Bh (see there)

  Bit7-6  Unused
  Bit5-3  Bitmap Base Address      (in 8K steps) (ROM/RAM see FF12h.Bit2)
  Bit2    Character/Bitmap ROM/RAM (0=RAM, 1=ROM) (Address see FF13h.Bit7-2)
  Bit1-0  Sound 2 Frequency MSB    (see Sound chapter)

  Bit7-2  Character Base Address (in 1K steps) (ROM/RAM see FF12h.Bit2)
  Bit1    Force single clock mode
  Bit0-??-Memory State READ ONLY (0=RAM, 1=ROM) (change via FF3Eh/FF3Fh)
  Bit0-??-Status of Clock

  Bit7-3  Video-ram Base Address (in 2K steps) (ROM/RAM see FF3Eh/FF3Fh)
  Bit2-0  Unused

  Port       Write       Read RAM   Read ROM
  FF3E       ROM SELECT  ?          HI ROM
  FF3F       RAM SELECT  ?          HI ROM

  A3-A2  HI-ROM C000h-FFFFh Select (0=Kernal, 1=FuncHI, 2=Cart1Hi, 3=Cart2Hi)
  A1-A0  LO-ROM 8000h-BFFFh Select (0=Basic, 1=FuncLO, 2=Cart1LO, 3=Cart2LO)

  Bit7    TEST Internal TED Test    (Should be always 0)
  Bit6    ECM  Enhanced color mode  (0=Normal, 1=Extended)
  Bit5    BMM  Bitmap mode          (0=Text, 1=Bitmap)
  Bit4    DEN  Display Enable       (0=Blank/Border Color, 1=Display Enable)
  Bit3    RSEL 24/25 rows screen    (0=24 Rows, 1=25 Rows)
  Bit2-0  Y2-0 Vertical smooth-scrolling

  Bit7         Reverse Mode  (0=Reverse/128 Chars, 1=No Reverse/256 Chars)
               If 0, higmost char-bit tells if char should appear in inverse.
  Bit6    NTSC Select Video Format  (0=PAL, 1=NTSC) (Don't change!)
  Bit5    RES  TED stop. If set, the TED stops it's counters and
               screen-generating, only single clock and refresh
               cycles remain.  PROJECT 64: Flashing (0=Yes, 1=No)
  Bit4    MCM  Multicolor mode      (0=Normal, 1=Multicolor)
  Bit3    CSEL 40/38 columns screen (0=38 Columns, 1=40 Columns)
  Bit2-0  X2-0 Horizontal smooth-scrolling

  Bit7    Not used
  Bit6-4  Luminance (Not used for Color Black)
  Bit3-0  Color

  0 ------ Black      8 RRG--- Orange
  1 R-G-B- White      9 R-g--- Brown
  2 RR---- Red       10 R-GG-- Yellow-Green
  3 --GGBB Cyan      11 RR--B- Pink
  4 RR--BB Purple    12 --G-BB Blue-Green
  5 --GG-- Green     13 R---BB Light Blue
  6 ----BB Blue      14 --g-B- Dark Blue
  7 RRGG-- Yellow    15 GG--B- Light Green

  Bit7    Unused
  Bit6-3  Flashing counter. It's value increases with every
             frame, and TED fits it's flashing feature to this
             register's reaching to 15.
  Bit2-0  Actual vertical scanning-line in a character-row (R/W!)

  1K color memory (1st 400h bytes of Color/Screen memory)
      bit7   Flashing   (Hires Text Mode only)
      bit6-4 Luminance  (Not used for Color Black)
      bit3   Multicolor (Multicolor Text Mode only)
      bit3-0 Color      (Only Bit2-0 in Multicolor Text Mode)
  1K screen memory (2nd 400h bytes of Color/Screen memory)
      bit7   Inversion         (Hires Text Mode, with FF07h/Bit7=0 only)
      bit7-6 Extended BG Color (Extended Text Mode only)
      bit7-0 Tile number 0-255 (max 127 or 63 for Inversion / Extended BG)
  2K character memory (800h bytes) (for 256 tiles)

  0  Background color 0 (Port FF15h)
  1  Color Memory (with Flashing Bit in Bit7)

  0  Background color 0-3 (Port FF15h-FF18h) select by upper 2bit of tileno
  1  Color Memory (Bit7 probably unused?)

  0  0  Background color 0 (Port FF15h)
  -  1  Background color 1 (Port FF16h)
  -  2  Background color 2 (Port FF17h)
  1  3  Color Memory (Bit3 selects Hires (0) or Color (1) tile-mode)
        (Multicolor mode uses only 6 bits for color/luminance)
        (Bit7 in Color Memory probably unused?)

  1K intensity memory (1st 400h bytes of Color/Screen memory)
      bit7   Not used
      bit6-4 Luminance MSB  (Not used for Color Black)
      bit3   Not used
      bit2-0 Luminance LSB  (Not used for Color Black)
  1K color memory (2nd 400h bytes of Color/Screen memory)
      bit7-4 Color MSB
      bit3-0 Color LSB
  8K bitmap (2000h bytes) (consisting of 40x25 tiles)

  0  Color LSB with Luminance MSB
  1  Color MSB with Luminance LSB

  0  Background color 0 (Port FF15h)
  1  Color LSB with Luminance MSB
  2  Color MSB with Luminance LSB
  3  Background color 1 (Port FF16h)

  Item          NTSC            PAL
  Oscillator    14.318181 MHz   17.734472 MHz
  Divider       Osc/16          Osc/20
  Single Clock  0.894886 MHz    0.886724 MHz
  Twice Clock   1.789773 MHz    1.773447 MHz
  Frame Rate    60Hz            50Hz
  Scanlines     262             312
  Clks/Line     57 single clks  57 single clks

    Dot clock = 8 times processor clock
    Two blocked DMA fetches per character line
    Writable horizontal and vertical sync counters
    Horizontal raster position register

  1 C16/C116: 5VDC via 330 Ohm - PLUS/4: N.C.
  2 GND
  3 ATN OUT
  4 CLK IN/OUT
  5 DATA IN/OUT
  6 /RESET OUT

  1 JOY0  Up    (TED K0 Input)
  2 JOY1  Down  (TED K1 Input)
  3 JOY2  Left  (TED K2 Input)
  4 JOY3  Right (TED K3 Input)
  5 5VDC
  6 BINA  Fire  (TED K6 or K7 Input)
  7 GND
  8 SELECT      (Amplified CPU databus D1 or D2 signal)

  SELECT  C16   C116       PLUS/4  BINA  BASIC
  D1=LOW  JOY2  JOY1/JOYB  JOY1    K7    JOY(2)
  D2=LOW  JOY1  JOY0/JOYA  JOY0    K6    JOY(1)

  1 GND
  2 5VDC
  3 MOTOR (9VDC)
  4 CAS RD
  5 CAS WRT
  6 SENSE
  7 GND

  1 LUM
  2 GND
  3 AUDIO OUT
  4 COMP
  5 EXT AUDIO IN
  6 COLOR
  7 N.C.
  8 C16/C116: 5VDC - PLUS4: N.C.

  Y-F       A0-A15
  21-14     D0-D7
  4,5,C     /IRQ, R/W, /RESET
  B,6,7,8   C1 LOW, C1 HIGH, C2 LOW, C2 HIGH
  9,10      /CS1, /CS0
  11,12,13  /CAS, MUX, BA
  D,E,24,22 /RAS, Phi0, Phi2, AEC
  2,3       5VDC
  I,A,CC,25 GND
  AA,BB     N.C.
  Z         N.C. (RAMEN ?)
  23        EXT AUDIO IN

  M,E,D,B8?,H,L,C   6551A TxD,DTR,RTS,RxC,DCD,DSR,RxD
  1,12,A,N          GND
  2                 5VDC
  10,11             9VAC1, 9VAC2
  9                 SIO ATN
  3                 /RESET (OUT)
  F,J,7,6,5,4,K,B8? 6529B P7-P0

  Bit    Col0  Col1  Col2  Col3  Col4  Col5  Col6  Col7
  Row0   DEL   "3"   "5"   "7"   "9"   "+"   PND   "1"
  Row1   RET   "W"   "R"   "Y"   "I"   "P"   "*"   <--
  Row2   RIGHT "A"   "D"   "G"   "J"   "L"   ";"   CTRL
  Row3   F7    "4"   "6"   "8"   "0"   "-"   HOME  "2"
  Row4   F1    "Z"   "C"   "B"   "M"   "."  RSHIFT SPC
  Row5   F3    "S"   "F"   "H"   "K"   ":"   "="   <C=>
  Row6   F5    "E"   "T"   "U"   "O"   "@"   "^"   "Q"
  Row7   DOWN LSHIFT "X"   "V"   "N"   ","   "/"   STOP

  C64   "-"    "+"    POUND HOME   DOWN   RIGHT  RSHIFT <--   "^"    "@"
  C16   UP     DOWN   LEFT  RIGHT  "@"    POUND  ESC?   HOME  "+"    "-"

  <--  1! 2" 3# 4$ 5% 6& 7' 8( 9) 0  +  -  PND HOME DEL  F1
  CTRL   Q  W  E  R  T  Y  U  I  O  P  @  *  ^  RESTORE  F3
  STP SHL A  S  D  F  G  H  J  K  L  :[ ;]  =  [RETURN]  F5
  C=  SHIFT Z  X  C  V  B  N  M  ,< .> /? SHIFT U/D L/R  F7
            [ _ _ _ _ _ SPACE _ _ _ _ _]

  ESC TAB ALT CAPS    HLP LF 40 SCR     UP DOWN LFT RGT  F1 F3 F5 F7
  <--  1! 2" 3# 4$ 5% 6& 7' 8( 9) 0  +  -  PND HOME DEL  7  8  9  +
  CTRL   Q  W  E  R  T  Y  U  I  O  P  @  *  ^  RESTORE  4  5  6  -
  STP SHL A  S  D  F  G  H  J  K  L  :[ ;]  =  [RETURN]  1  2  3  EN-
  C=  SHIFT Z  X  C  V  B  N  M  ,< .> /? SHIFT U/D L/R  [-0-] .  TER
            [ _ _ _ _ _ SPACE _ _ _ _ _]

  ESC 1 2 3 4 5 6 7 8 9 0 L R U D DEL F1
  CTRL Q W E R T Y U I O P @ + - HOME F2
  RN SL A S D F G H J K L ; : * RETRN F3
  C= SHF Z X C V B N M , . / SHF $ =  HELP
         [------SPACE------]

      F1  F2  F3  HELP  HOME? DEL?
  ESC 1 2 3 4 5 6 7 8 9 0 + - *
  CTRL Q W E R T Y U I O P @ RET
  RUN $ A S D F G H J K L [  ] =   _|_
  C= SHF Z X C V B N M , . / SHF    |
         [------SPACE------]

      F1  F2  F3  HELP                     <-- reset button (side)
  ESC 1 2 3 4 5 6 7 8 9 0 + - = HOME DEL
  CTRL Q W E R T Y U I O P @ PND *  CTRL
  RN SL A S D F G H J K L [  ] RETURN
  C= SHF Z X C V B N M , . / SHF   _|_
           [-----SPACE-----]        |

  Key   Full name   Normal use            Shifted use
  HOME  CLR/HOME    Move cursor to 0,0    Move to 0,0 and clear screen
  DEL   INST/DEL    Backspace             Insert one SPACE not moving cursor
  STP   RUN/STOP    Stop/Break            Start Cassette Loading (LOAD+RUN)
  C=    COMMODORE   Keycombinations...    Toggle Character Set 1 and 2
  U/D   CRSR        Cursor Down           Cursor Up
  L/R   CRSR        Cursor Right          Cursor Left
  F1/F2 FUNCTION    F1                    F2
  F3/F4 FUNCTION    F3                    F4
  F5/F6 FUNCTION    F5                    F6
  F7/F8 FUNCTION    F7                    F8

     The KERNAL then checks for the presence of an autostart ROM cartridge
     at location C64:8000h, VIC20:A000h. If this is present, normal
     initialization is suspended, and control is transferred to the car-
     tridge code.

  The following codes are used by the Commodore 64 to stand for the
  CBM devices listed below:
    ADDRESS  DEVICE
    0        Keyboard
    1        Datassette(TM)
    2        RS-232C device
    3        CRT display
    4        Serial bus printer
    8        CBM serial bus disk drive
  Device numbers 4 or greater automatically refer to devices on the
  serial bus.
    A command to the device is sent as a secondary address on the serial
  bus after the device number is sent during the serial attention
  handshaking sequence. If no secondary address is to be sent, the Y index
  register should be set to 255.

    Registers affected: A, X, Y

  Preparatory routines: CHKIN, OPEN
  Error returns: See READST
 Description: If the channel is the keyboard, this subroutine removes
  one character from the keyboard queue and returns it as an ASCII value in
  the accumulator. If the queue is empty, the value returned in the
  accumulator will be zero. Characters are put into the queue automatically
  by an interrupt driven keyboard scan routine which calls the SCNKEY
  routine. The keyboard buffer can hold up to ten characters. After the
  buffer is filled, additional characters are ignored until at least one
  character has been removed from the queue.
 If the channel is RS-232, then
  only the A register is used and a single character is returned. See
  READST to check validity. If the channel is serial, cassette, or screen,
  call BASIN routine.

  How to Use:
    1) Call this routine using a JSR instruction.
    2) Check for a zero in the accumulator (empty buffer).
    3) Process the data.
  EXAMPLE:
         ;WAIT FOR A CHARACTER
    WAIT JSR GETIN
         CMP #0
         BEQ WAIT

  +-----------------------------------------------------------------------+
  | NOTE: Care must be taken when using this routine to send data to a    |
  | specific serial device since data will be sent to all open output     |
  | channels on the bus. Unless this is desired, all open output channels |
  | on the serial bus other than the intended destination channel must be |
  | closed by a call to the KERNAL CLRCHN routine.                        |
  +-----------------------------------------------------------------------+

  Description: This routine is called to clear all open channels and re-
  store the I/O channels to their original default values. It is usually
  called after opening other I/O channels (like a tape or disk drive) and
  using them for input/output operations. The default input device is 0
  (keyboard). The default output device is 3 (the Commodore 64 screen).
    If one of the channels to be closed is to the serial port, an UNTALK
  signal is sent first to clear the input channel or an UNLISTEN is sent to
  clear the output channel. By not calling this routine (and leaving lis-
  tener(s) active on the serial bus) several devices can receive the same
  data from the Commodore 64 at the same time. One way to take advantage
  of this would be to command the printer to TALK and the disk to LISTEN.
  This would allow direct printing of a disk file.
    This routine is automatically called when the KERNAL CLALL routine is
  executed.

  Description: This routine is used to close a logical file after all I/O
  operations have been completed on that file. This routine is called after
  the accumulator is loaded with the logical file number to be closed (the
  same number used when the file was opened using the OPEN routine).

  Description: This routine closes all open files. When this routine is
  called, the pointers into the open file table are reset, closing all
  files. Also, the CLRCHN routine is automatically called to reset the I/O
  channels.

  This routine always buffers one character. (The routine holds the previous
  character to be sent back.) So when a call to the UNLSN routine is made to
  end the data transmission, the buffered character is sent with an End Or
  Identify (EOI) set. Then the UNLSN command is sent to the device.

  In: A=Device Number (0-1Fh)
  Error returns: See READST
  Registers affected: A

    Communication registers: A
    Preparatory routines: LISTEN
    Error returns: See READST
    Registers affected: A
  Description: This routine is used to send a secondary address to an
  I/O device after a call to the LISTEN routine is made, and the device is
  commanded to LISTEN. The routine can NOT be used to send a secondary
  address after a call to the TALK routine.
  A secondary address is usually used to give setup information to a
  device before I/O operations begin.
  When a secondary address is to be sent to a device on the serial bus,
  the address must first be ORed with $60.

  In: N/A - Out: A=Destroyed
  Error returns: See READST

  In: N/A - Out: A=Destroyed
  Error returns: See READST

  Description: This routine sets up the 6567 video controller chip in the
  Commodore 64 for normal operation. The KERNAL screen editor is also
  initialized. This routine should be called by a Commodore 64 program
  cartridge.

  Description: This routine initializes all input/output devices and
  routines. It is normally called as part of the initialization procedure
  of a Commodore 64 program cartridge.

  Description: This routine is used to test RAM and set the top and
  bottom of memory pointers accordingly. It also clears locations $0000 to
  $0101 and $0200 to $03FF. It also allocates the cassette buffer, and sets
  the screen base to $0400. Normally, this routine is called as part of the
  initialization process of a Commodore 64 program cartridge.

  Description: This routine restores the default values of all system
  vectors used in KERNAL and BASIC routines and interrupts. (See the Memory
  Map for the default vector contents). The VECTOR routine is used
  to read and alter individual system vectors.

  Get: In: Cy=1, Y:X=Target Address - Out: A,X,Y=Destroyed
  Set: In: Cy=0, Y:X=Source Address - Out: A,X,Y=Destroyed

  Set: In: Cy=0, Y:X=Address
  Get: In: Cy=1 - Out: Y:X=Address (usually 800h on C64)

  Set: In: Cy=0, Y:X=Address
  Get: In: Cy=1 - Out: Y:X=Address (usually A000h on C64)

  In: N/A - Out: A,X,Y=Destroyed

  Out: X=Width, Y=Height (40x25 for C64/C16, 22x23 for VIC20)

  Set: In: Cy=0, X=0..24, Y=0..39 - Out: A=Destroyed
  Get: In: Cy=1 - Out: X=0..24, Y=0..39

  In: N/A - Out: Y:X:A=Time in 1/60 seconds (jiffies)
  The clock range is 24 hours, 0..5183999 (0..4F19FFh) jiffies,
  and starts over at zero when exceeding that range.

  In: A.Bit7 Timeout Flag (0=Set/Enable, 1=Reset/Disable) - Out: Same

  Description: When the timeout flag is set, the Kernal will wait for a
  device on the IEEE port for 64 milliseconds. If the device does not
  respond to the Data Address Valid (DAV) signal within that time then the
  Kernal will recognize an error condition and leave the handshake sequence.

  In: N/A - Out: A,X=Destroyed, Zeroflag=STOP Flag

  ERROR RETURNS: A return from a KERNAL routine with the CARRY set
  indicates that an error was encountered in processing. The accumulator
  will contain the number of the error.
  NOTE: Some KERNAL I/O routines do not use these codes for error
  messages. Instead, errors are identified using the KERNAL READST
  routine.

  If an error occurs during a KERNAL routine, the carry bit is set,
  and the number of the error message is returned in the accumulator.
  Num  Expl.
  0    Routine terminated by the <STOP> key
  1    Too many open files
  2    File already open
  3    File not open
  4    File not found
  5    Device not present
  6    File is not an input file
  7    File is not an output file
  8    File name is missing
  9    Illegal device number
  240  Top-of-memory change RS-232 buffer allocation/deallocation

  Bit  Expl.
  0    Serial Bus: Time out write
  1    Serial Bus: Time out read
  2    Cassette: Short Block
  3    Cassette: Long Block
  4    Cassette: Any mismatch/Unrecoverable read error
  5    Cassette: Checksum error
  6    Cassette: End of file, Serial Bus: EOI line (End Or Identify)
  7    Cassette: End of tape, Serial Bus: Device not present

    Communication registers: A
    Registers affected: A
  Bit7  0=Disable, 1=Enable Control Messages (eg. PRESS PLAY ON CASSETTE)
  Bit6  0=Disable, 1=Enable Error Messages   (eg. FILE NOT FOUND)

  Address      Name    Expl.
  0000h        D6510   C64: 6510 On-Chip Data-Direction Register
  0001h        R6510   C64: 6510 On-Chip Data-Input/Output Register
  0002h                C64: Unused

  0000h                VIC20: USR Function JMP Opcode (4Ch) (C64: see 0310h)
  0001h-0002h          VIC20: USR Function Vector (MSB,LSB) (C64: see 0311h)
  0003h-0004h  ADRAY1  Jump Vector: Convert Float--Integer
  0005h-0006h  ADRAY2  Jump Vector: Convert Integer--Float
  0007h        CHARAC  Search Character
  0008h        ENDCHR  Flag: Scan for Quote at End of String
  0009h        TRMPOS  Screen Column From Last TAB
  000Ah        VERCK   Flag: 0=Load, 1=Verify
  000Bh        COUNT   Input Buffer Pointer / Number of Subscripts
  000Ch        DIMFLG  Flag: Default Array DIMension
  000Dh        VALTYP  Data Type: FFh=String, 00h=Numeric
  000Eh        INTFLG  Data Type: 80h=Integer, 00h=Float
  000Fh        GARBFL  Flag: DATA scan/LIST quote/Garbage Coll
  0010h        SUBFLG  Flag: Subscript Ref / User FNx Function Call
  0011h        INPFLG  Flag: 00h=INPUT, 40h=GET, 98h=READ
  0012h        TANSGN  Flag: ATN/TAN sign / Comparison Result
  0013h                Flag: INPUT Prompt
  0014h-0015h  LINNUM  Temp: Integer Value (see Float conversion 0003h,0005h)
  0016h        TEMPPT  Pointer Temporary String Stack
  0017h-0018h  LASTPT  Last Temp String Address
  0019h-0021h  TEMPST  Stack for Temporary Strings
  0022h-0025h  INDEX   Utility Pointer Area (0022h: INDEX1, 0024h: INDEX2)
  0026h-002Ah  RESHO   Floating-Point Product of Multiply
  002Bh-002Ch  TXTTAB  Pointer: Start of BASIC Program
  002Dh-002Eh  VARTAB  Pointer: Start of BASIC Variables (End of Basic program)
  002Fh-0030h  ARYTAB  Pointer: Start of BASIC Arrays (End of Variables)
  0031h-0032h  STREND  Pointer: Start of free memory (End of Arrays+1)
  0033h-0034h  FRETOP  Pointer: Bottom of String Storage (End of Free memory)
  0035h-0036h  FRESPC  Utility String Pointer
  0037h-0038h  MEMSIZ  Pointer: Highest Address Used by BASIC (End of Strings)
  0039h-003Ah  CURLIN  Current BASIC Line Number
  003Bh-003Ch  OLDLIN  Previous BASIC Line Number
  003Dh-003Eh  OLDTXT  Pointer: BASIC Statement for CONT
  003Fh-0040h  DATLIN  Current DATA Line Number
  0041h-0042h  DATPTR  Pointer: Current DATA Item Address
  0043h-0044h  INPPTR  Vector: INPUT Routine
  0045h-0046h  VARNAM  Current BASIC Variable Name
  0047h-0048h  VARPNT  Current BASIC Variable Address (Pointer)
  0049h-004Ah  FORPNT  Pointer: Index Variable for FOR/NEXT
  004Bh-0060h          Temp Pointer / Data Area
  004Bh-004Ch  VARTXT  Temporary storage for TXTPTR during READ, INPUT, GET
  004Dh        OPMASK  Mask used during FRMEVL / Comparison symbol accumulator
  004Eh-0052h  TEMPF3  Temporary storage for FLPT value.
  0053h        FOUR6   Length of String Variable during Garbage collection.
  0054h-0056h  JMPER   Jump Vector used in Function Evaluation (4Ch, LSB, MSB)
  0057h-005Bh  TEMPF1  Temporary storage for FLPT value.
  005Ch-0060h  TEMPF2  Temporary storage for FLPT value.

  0061h-0066h  FAC     Floating-Point Accumulator 1 (Exp,4-Byte Mantissa,Sign)
  0067h        SGNFLG  Pointer: Series Evaluation Constant
  0068h        BITS    Floating-Point Accumulator 1 (Overflow Digit)
  0069h-006Eh  ARG     Floating-Point Accumulator 2 (Exp,4-Byte Mantissa,Sign)
  006Fh        ARISGN  Sign Comparison Result: Accumulator 1 vs 2
  0070h        FACOV   Floating-Point Accumulator 1 (Low-Order, Rounding)
  0071h-0072h  FBUFPT  Pointer: Cassette Buffer
  0073h-0078h  CHRGET  Subroutine: Get Next Byte of BASIC Text
  0079h        CHRGOT  Subroutine: Entry to Get Same Byte of Text Again
  007Ah-007Bh  TXTPTR  Pointer: Current Byte of BASIC Text
  007Ch-008A           Subroutine: Rest of the CHRGET/CHRGOT Subroutines
  008Bh-008Fh  RNDX    Floating RND Function Seed Value

  0090h        STATUS  Kernal I/O Status Word: ST
  0091h        STKEY   Flag: STOP key / RVS key
  0092h        SVXT    Timing Constant for Tape
  0093h        VERCK   Flag: 0=Load, 1=Verify
  0094h        C3PO    Flag: Serial Bus-Output Character Buffered
  0095h        BSOUR   Buffered Character for Serial Bus
  0096h        SYNO    Cassette Sync No. / Tape EOT received
  0097h                Temp Data Area / Register save
  0098h        LDTND   Number of Open Files / Index to File Table
  0099h        DFLTN   Default Input Device (normally 0=Keyboard)
  009Ah        DFLTO   Default Output (CMD) Device (normally 3=Screen)
  009Bh        PRTY    Tape Character Parity
  009Ch        DPSW    Flag: Tape Byte-Received
  009Dh        MSGFLG  Flag: 80h=Direct Mode, 00h=Program RUN
  009Eh        PTR1    Tape Pass 1 Error Log
  009Fh        PTR2    Tape Pass 2 Error Log
  00A0h-00A2h  TIME    60Hz Real-Time Jiffy Clock (approx) 1/60 Sec
  00A3h-00A4h          Temp Data Area
  00A5h        CNTDN   Cassette Sync Countdown
  00A6h        BUFPNT  Pointer: Tape I/O Buffer
  00A7h        INBIT   RS-232 Input Bits / Cassette Temp
  00A8h        BITCI   RS-232 Input Bit Count / Cassette Temp
  00A9h        RINONE  RS-232 Flag: Check for Start Bit
  00AAh        RIDATA  RS-232 Input Byte Buffer/Cassette Temp
  00ABh        RIPRTY  RS-232 Input Parity / Cassette Short Cnt
  00ACh-00ADh  SAL     Pointer: Tape Buffer / Screen Scrolling
  00AEh-00AFh  EAL     Tape End Addresses/End of Program
  00B0h-00B1h  CMP0    Tape Timing Constants
  00B2h-00B3h  TAPE1   Pointer: Start of Tape Buffer
  00B4h        BITTS   RS-232 Out Bit Count / Cassette Temp
  00B5h        NXTBIT  RS-232 Next Bit to Send/ Tape EOT Flag
  00B6h        RODATA  RS-232 Out Byte Buffer
  00B7h        FNLEN   Length of Current File Name
  00B8h        LA      Current Logical File Number
  00B9h        SA      Current Secondary Address
  00BAh        FA      Current Device Number
  00BBh-00BCh  FNADR   Pointer: Current File Name
  00BDh        ROPRTY  RS-232 Out Parity / Cassette Temp
  00BEh        FSBLK   Cassette Read / Write Block Count
  00BFh        MYCH    Serial Word Buffer
  00C0h        CAS1    Tape Motor Interlock
  00C1h-00C2h  STAL    I/O Start Address (VIC20:8000h, C64:A000h) (both wrong?)
  00C3h-00C4h  MEMUSS  Tape Load Temps / VIC20: KERNAL setup pointer
  00C5h        LSTX    Current Key Pressed (40h=None) (0-3Fh=Key Number)
                       The Key Numbers differ on C64/VIC20. If more than 1 key
                       is down, the key with the highest number shows up here.
                       Not used for special keys like SHIFT, CTRL, etc.
  00C6h        NDX     Number of Chars in Keyboard Buffer (see also: 0277h)
  00C7h        RVS     Flag: Reverse Chars (01h=On/Yes, 00h=Off/Not Used)
  00C8h        INDX    Pointer: End of Logical Line for INPUT
  00C9h-00CAh  LXSP    Cursor X,Y Position at Start of INPUT
  00CBh        SFDX    C64: Flag: Print Shifted Chars.
  00CBh                VIC20: Current key pressed (same as 00C5h)
  00CCh        BLNSW   Cursor Blink enable (0=Flash Cursor) (copy of 00C6h)
  00CDh        BLNCT   Timer: Countdown to Toggle Cursor
  00CEh        GDBLN   Character Under Cursor
  00CFh        BLNON   Flag: Last Cursor Blink On/Off
  00D0h        CRSW    Flag: INPUT or GET from Keyboard / from screen
  00D1h-00D2h  PNT     Pointer: Cursor Current Screen Line Address
  00D3h        PNTR    Cursor Column on Current Line
  00D4h        QTSW    Flag: Editor in Quote Mode (00h=No/Direct Cursor)
  00D5h        LNMX    Screen Line Length, screen_width*(1..4)-1
  00D6h        TBLX    Current Cursor Line Number (see also: 00D1h-00D2h,00D3h)
  00D7h                Temp Data Area, last inkey/checksum/buffer
  00D8h        INSRT   Insert Mode (00h=Disable, NNh=Number of spaces left)
  00D9h-00F2h  LDTB1   Screen Line Link Table / Editor Temps
  00F3h-00F4h  USER    Pointer: Current Screen Color RAM location
  00F5h-00F6h  KEYTAB  Pointer: Current Keyboard Decode Table (Norm,Shift,etc.)
  00F7h-00F8h  RIBUF   RS-232 Input Rcv Buffer Pointer
  00F9h-00FAh  ROBUF   RS-232 Output Tx Buffer Pointer
  00FBh-00FEh  FREKZP  User Program Zero-Page Space (not used by BASIC/KERNAL)
  00FFh        BASZPT  BASIC Temp Data Area

  0100h-01FFh          Micro-Processor System Stack Area
   0100h-010Ah         Floating to String Work Area
   0100h-013Eh BAD     Tape Error Log

  0200h-0258h  BUF     System INPUT Buffer
  0259h-0262h  LAT     KERNAL Table: Active OPEN Logical File Numbers
  0263h-026Ch  FAT     KERNAL Table: Device Number for each File
  026Dh-0276h  SAT     KERNAL Table: Secondary Address for each File
  0277h-0280h  KEYD    Keyboard Buffer Queue (see also: 00C6h,0289h)
  0281h-0282h  MEMSTR  Pointer: Bottom of Memory for Operating System
  0283h-0284h  MEMSIZ  Pointer: Top of Memory for Operating System
  0285h        TIMOUT  Flag: Kernal Variable for IEEE or Serial Timeout
  0286h        COLOR   Current Character Color Code
  0287h        GDCOL   Background Color Under Cursor
  0288h        HIBASE  Start of Screen Memory (MSB=Page)
  0289h        XMAX    Size of Keyboard Buffer (max 0Ah, see also: 0277h,0289h)
  028Ah        RPTFLG  Flag: Key Repeat (00h=Cursor Keys, 80h=All keys)
  028Bh        KOUNT   Key Repeat Speed Counter
  028Ch        DELAY   Key Repeat Delay Counter
  028Dh        SHFLAG  Keyboard Flags (Bit0=Shift, Bit1=Commodore, Bit2=Ctrl)
  028Eh        LSTSHF  Last Keyboard Shift Pattern
  028Fh-0290h  KEYLOG  Vector: Keyboard Table Setup / Decode Logic
  0291h        MODE    Flag: SHIFT+COMMODORE Case Switch (0=Enable,80h=Disable)
  0292h        AUTODN  Flag: Auto Scroll Down (0=On, other=Off)
  0293h        M51CTR  RS-232: 6551 Control Register Image
  0294h        MS1CDR  RS-232: 6551 Command Register Image
  0295h-0296h  M51AJB  RS-232 Non-Standard BPS (Time/2-100) USA
  0297h        RSSTAT  RS-232: 6551 Status Register Image
  0298h        BITNUM  RS-232 Number of bits left to send
  0299h-029Ah  BAUDOF  RS-232 Baud Rate: Full Bit Time (us)
  029Bh        RIDBE   RS-232 Index to Input Buffer End
  029Ch        RIDBS   RS-232 Start of Input Buffer (Page)
  029Dh        RODBS   RS-232 Start of Output Buffer (Page)
  029Eh        RODBE   RS-232 Index to Output Buffer End
  029Fh-02A0h  IRQTMP  Holds IRQ Vector During Tape I/O
  02A1h-02FFh          VIC20: Program indirects
  02A1h        ENABL   C64: RS-232 Enables
  02A2h                C64: TOD Sense During Cassette I/O
  02A3h                C64: Temp Storage For Cassette Read
  02A4h                C64: Temp D1 IRQ Indicator For Cassette Read
  02A5h                C64: Temp For Line Index
  02A6h                C64: PAL/NTSC Flag, 0= NTSC, 1 = PAL
  02A7h-02FFh          C64: Unused
  0300h-0301h  IERROR  Vector: Print BASIC Error Message
  0302h-0303h  IMAIN   Vector: BASIC Warm Start
  0304h-0305h  ICRNCH  Vector: Tokenize BASIC Text (Crunch)
  0306h-0307h  IQPLOP  Vector: BASIC Text LIST (Print Tokens)
  0308h-0309h  IGONE   Vector: BASIC Char. Dispatch / Start new Basic code link
  030Ah-030Bh  IEVAL   Vector: BASIC Token Evaluation / arithmetic element link
  030Ch-030Fh  SxREG   Storage for 6502 Registers A,X,Y,P
  0310h-0313h          VIC20: Unused ?
  0310h        USRPOK  C64: USR Function JMP Opcode (4Ch) (VIC20: see 0000h)
  0311h-0312h  USRADD  C64: USR Function Vector (LSB,MSB) (VIC20: see 0001h)
  0313h                C64: Unused
  0314h-0315h  CINV    CPU IRQ Vector (redirected IRQ with A,X,Y pushed)
  0316h-0317h  CBINV   CPU BRK Vector (redirected BRK with A,X,Y pushed)
  0318h-0319h  NMINV   CPU NMI Vector (redirected NMI without anything pushed)
  031Ah-031Bh  IOPEN   KERNAL OPEN Vector
  031Ch-031Dh  ICLOSE  KERNAL CLOSE Vector
  031Eh-031Fh  ICHKIN  KERNAL CHKIN Vector
  0320h-0321h  ICKOUT  KERNAL CHKOUT Vector
  0322h-0323h  ICLRCH  KERNAL CLRCHN Vector
  0324h-0325h  IBASIN  KERNAL CHRIN Vector
  0326h-0327h  IBSOUT  KERNAL CHROUT Vector
  0328h-0329h  ISTOP   KERNAL STOP Vector
  032Ah-032Bh  IGETIN  KERNAL GETIN Vector
  032Ch-032Dh  ICLALL  KERNAL CLALL Vector
  032Eh-032Fh  USRCMD  User-Defined Vector
  0330h-0331h  ILOAD   KERNAL LOAD Vector
  0332h-0333h  ISAVE   KERNAL SAVE Vector
  0334h-033Bh          Unused

  033Ch-03FBh  TBUFFR  Tape I/O Buffer (General purpose RAM when CAS not used)
  03FCh-03FFh          Unused

  Bit  Expl.
  7-0  Input/Output lines PB7..PB0      (0=Low, 1=High)

  Bit  Expl.
  7-0  Input/Output lines PA7..PA0      (0=Low, 1=High)

  Bit  Expl.
  7-0  Direction for Data Port Bits 7-0  (0=Input, 1=Output)

  Reading port 04h/05h returns the upper/lower T1 counter value.
  Reading port 06h/07h returns the lower/upper T1 latch value.
  Reading port 04h resets the T1 interrupt flag (IFR.6).
  Writing port 04h/05h or 06h/07h sets lower/upper bits of the T1 <latch>.
  Writing port 05h copies the 16bit T1 latch to the 16bit T1 counter.
  Writing port 05h/07h resets the T1 interrupt flag (IFR.6).

  Writing to 08h sets the T2 low-order <latch>.
  Writing to 09h sets the T2 high-order <counter>.
  Writing to 09h also copies lower-order latch to low-order counter.
  Writing to 09h additionally resets the T2 interrupt flag (IFR.5).
  Reading from 08h/09h returns the low/high-order T2 counter value.
  Reading from 08h additionally resets the T2 interrupt flag (IFR.5).

  Reading/writing SR resets the shift counter, and, in most shift modes,
  starts the transfer and generates an interrupt once the shift counter
  reaches a value of eight.

  Bit  Expl.
  7    T1 Toggle PB7 Output     (0=Disable, 1=Invert PB7 upon underflow)
  6    T1 Continous Mode        (0=One-Shot, 1=Restart upon underflow)
  5    T2 Clock Source          (0=System clock, 1=PB6 negative edge)
  4    Shift Register Direction (0=Shift In, 1=Shift Out)
  3-2  Shift Register Mode      (0-3, see below)
  1    PB Latching Enable       (0=Disable, 1=Latch PB on CB1 Interrupt Flag)
  0    PA Latching Enable       (0=Disable, 1=Latch PA on CA1 Interrupt Flag)

  0=Free-Run (when Bit4=1), or Disabled (when Bit4=0)
  1=Shift at System 02 Clock rate divided by (2+T2C_L)
  2=Shift at System 02 Clock rate divided by 2
  3=Shift at external CB1 clock rate

  Bit  Expl.
  7-5  CB2 Input/Output Control (0-7, see below)
  4    CB1 Input Control        (0-1, see below)
  3-1  CA2 Input/Output Control (0-7, see below)
  0    CA1 Input Control        (0-1, see below)

  0 (In)  Interrupt on negative CX2 edge, Acknowldge by read/write Port PX
  1 (In)  Interrupt on negative CX2 edge, Independent (without ack via PX)
  2 (In)  Interrupt on positive CX2 edge, Acknowldge by read/write Port PX
  3 (In)  Interrupt on positive CX2 edge, Independent (without ack via PX)
  4 (Out) Handshake (CX2=LOW on write Port B, CX2=HIGH on active CX1 edge)
  5 (Out) Pulse     (CX2=LOW for 1 cycle on write to Port PX)
  6 (Out) Manual    (CX2=LOW)
  7 (Out) Manual    (CX2=HIGH)

  0 (In)  Interrupt on negative CX1 edge, Acknowldge by read/write Port PX
  1 (In)  Interrupt on positive CX1 edge, Acknowldge by read/write Port PX

  Bit  Set by                 Cleared by
  0    CA2 Active edge        Read or write ORA (except in Independed mode)
  1    CA1 Active edge        Read or write ORA
  2    Completed 8 shifts     Read or write SR
  3    CB2 Active edge        Read or write ORB (except in Independed mode)
  4    CB1 Active edge        Read or write ORB
  5    T2 Underflow           Read T2 low or write T2 high
  6    T1 Underflow           Read T1 low or write T1 high
  7    Any enabled interrupt  Cleared only when (IER AND IFR AND 7Fh)=00h

  Write IFR 0-6   Interrupt Acknowledge           (0=Keep, 1=Set to Zero)
  Write IFR 7     No function                     (Don't care)
  Read IFR 0-6    Interrupt Request Flags         (0=None, 1=Interrupt Request)
  Read IFR 7      Interrupt signal, set when IER AND IFR AND 7Fh is nonzero

  Write/IER 0-6   Select Interrupt Enable Bits    (0=Keep, 1=Set to Bit7)
  Write/IER 7     New Value for Selected IER Bits (0=Disable, 1=Enable)
  Read/IER 0-6    Current Value of IER Bits 0-6   (0=Disabled, 1=Enabled)
  Read/IER 7      Not used                        (Always 1)

  Pin(s)  Dir  Purpose
  PA0-7   I/O  Eight general purpose I/O pins
  PB0-7   I/O  Eight general purpose I/O pins
  PB6     In   Optionally used as Timer T2 clock source (negative edge)
  PB7     Out  Optionally toggled on each T1 Timer underflow
  CA1/CB1 In   Edge triggered IRQ (with optional Port A/B latching)
  CA2/CB2 In   Edge triggered IRQ (with optional Port A/B Acknowledge)
  CA1/CB1 In   Port A/B handshake input
  CA2/CB2 Out  Fixed High/Low, or Port A/B Handshake output
  CB1/CB2 I/O  Shift-Register clock/data
  IRQ     Out  Interrupt signal send to CPU's /IRQ or /NMI input

  CPU 6502 ???MHz, 16K ROM, 2K RAM, two 6522 I/O and timer chips
  Read/Write Speed ??? Serial Bus Rate ???
  Two serial bus sockets (one towards computer, other for further devices)
  Power Supply: 100-240V AC, 25 Watts (internally using +5V and +12V)
  Height 97 mm, Width 200 mm, Depth 374 mm, Weight 16 tons
  Diskettes: Standard mini 5 1/4", Single Sided (SS), Single Density (SD)
  Formatting: 35 Tracks, 17-21 sectors per track, 256 bytes per sector
  Total Capacity: 174848 bytes (683 blocks, 256 bytes each)
  Free Space: 168656 bytes (664 blocks, 256-2 bytes each)
  Directory: 144 files per diskette, 16 characters per filename (19 blocks)

 LOAD "*",8             ;load first file on disk (or recently accessed file)
 LOAD "FILENAME",8      ;load a specific file by name
 LOAD "FILENAME",8:RUN  ;load and start a file
 LOAD "$",8:LIST        ;load and view the directory
 LOAD "$0:FILE*",8:LIST ;load and view specific names in the directory
 SAVE "FILENAME",8      ;save a file to disk
 SAVE "@0:FILENAME",8   ;save a file to disk and delete old file of same name
 VERIFY "FILENAME",8    ;compare specified file with program in memory

  /filename     load a program from disk
  >    or @     read and display error channel
  >$   or @$    read and display directory
  >cmd or @cmd  send command to drive

  LOAD   file_name, device_number [,command_number]
  SAVE   file_name, device_number [,command_number]
  VERIFY file_name, device_number
  OPEN   file_number, device_number, channel_number [,file_name]
  PRINT# file_number, variable list
  INPUT# file_number, variable list
  GET#   file_number, variable list
  CLOSE  file_number
  STATUS, CHR$, ASC

  Addr  Name    Expl.
  FFBA  SETLFS  Set logical/physical/secondary address (fileno,device,channel)
  FFBD  SETNAM  Set length and address of filename
  FFC0  OPEN    Open a file (parameters must be prepared by SETLFS/SETNAM)
  FFC3  CLOSE   Close a file
  FFC6  CHKIN   Select file_number for CHRIN
  FFC9  CHKOUT  Select file_number for CHROUT
  FFCC  CLRCHN  Clear all channels (undoes or terminates CHKIN/CHKOUT ???)
  FFCF  CHRIN   Read a byte from the file being selected by CHKIN
  FFD2  CHROUT  Write a byte to the file being selected by CHKOUT

  device_number  values 8-11 for 1st-4th attached drive unit (usually 8)
  drive_number   always 0 for normal drives, value 0-1 for dual drives
  file_number    file handle in computer (use any value 1-127)
  channel_number file handle in drive (0-1 reserved, 2-14 data, 15 cmd/err)
  file_name      ASCII filename (misused to contain parameters in some cases)
  command_number

  When using the PRINT# statement, if you use commas (,) to separate
  items on the line, the items will be separated by some blank spaces,
  as if it were being formatted for the screen.  Semicolons (;) don't
  result in any extra spaces.

  Numeric data written in the file takes the form of a string, as if the
  STR$ function had been performed on it before writing it out.  The
  first character will be a blank space if the number is positive, and a
  minus sign (-) if the number is negative.  Then comes the number, and
  the last character is the cursor right character.

  "COMMAND:parameters",0dh
  "SPECIAL-COMMAND:parameters",0dh

  "C:parameters",0dh
  "S-C:parameters",0dh

  "NEW:name,id"  format the entire disk, and set disk name and 2 chars ID
  "NEW:name"     clears the directory without re-formatting the whole disk
  "COPY:newfile=oldfile"      copy a file (source and dest both on same disk)
  "COPY:newfile=f1,f2,f3,f4"  copy max 4 files into 1 file
  "RENAME:newname=oldname"    rename a file
  "SCRATCH:name"              delete a file (may use wildcards)
  "INITIALIZE"          closes any open files and reboots the drive
  "VALIDATE"            defragments the disk (do not use with random files)
  "DUPLICATE"           reserved for dual drives (1:1 copy of a whole disk)

 NEW                "N
 COPY               "C:new file=:original file
 RENAME             "R:new name=old name"
 SCRATCH            "S:file name"
 INITIALIZE         "I
 VALIDATE           "V
 DUPLICATE          not for single drives
 C64/default speed  "UI+"
 VIC 20 speed       "UI-"

 BLOCK-ALLOCATE     "B-A: drive track block"
 BLOCK-FREE         "B-F: drive track block"
 BLOCK-READ         "B-R: channel drive track block"
 BLOCK-WRITE        "B-W: channel drive track block"
 BLOCK-EXECUTE      "B-E: channel drive track block"
 BUFFER-POINTER     "B-P: channel position"
 USER1 (UA) (READ)  "U1: channel drive track block"
 USER2 (UB) (WRITE) "U2: channel drive track block"

 POSITION           "P", channel+96, record_lsb, record_msb [,position]

 MEMORY-READ        "M-R", address_lsb, address_msb
 MEMORY-WRITE       "M-W", address_lsb, address_msb, length, data[length]
 MEMORY-EXECUTE     "M-E", address_lsb, address_msb
 USER Commands      "Un"

 U3 or UC      jump to 0500h
 U4 or UD      jump to 0503h
 U5 or UE      jump to 0506h
 U6 or UF      jump to 0509h
 U7 or UG      jump to 050Ch
 U8 or UH      jump to 050Fh
 U; or UJ      jump to [FFFC] power-up vector

  "NN,NAME,TR,BL",0dh

  00 OK                 - No error.
  01 NAME???      - No error. Response to SCRATCH (TR=number of files deleted)
  02-19 N/A       - No error. Reserved for status messages (should be ignored)
  20 READ ERROR         - Block header not found
  21 READ ERROR         - No sync mark found on track
  22 READ ERROR         - Data block not present
  23 READ ERROR         - Checksum error in data block
  24 READ ERROR         - Byte decoding error
  25 WRITE ERROR        - Write-verify error
  26 WRITE PROTECT ON   - Attempt to write with closed write-protect notch
  27 READ ERROR         - Checksum error in header
  28 WRITE ERROR        - No sync mark found after written data block
  29 DISK ID MISMATCH   - Unformatted disk or bad header
  30 SYNTAX ERROR       - Invalid command parameters
  31 SYNTAX ERROR       - Unrecognized command
  32 SYNTAX ERROR       - Command/parameters longer than 58 characters
  33 SYNTAX ERROR       - Wildcards used in OPEN/SAVE command
  34 SYNTAX ERROR       - Missing filename in command string
  39 SYNTAX ERROR       - Unrecognized command. "Command file not found" ???
  50 RECORD NOT PRESENT - Reading past the last record.
   Positioning to a record beyond end of file in a relative file. If the
   intent is to expand the file by adding the new record (with a PRINT#
   command), the error message may be ignored. INPUT or GET should not be
   attempted after this error is detected without first repositioning.
  51 OVERFLOW IN RECORD - Writing exceeds record boundary.
  52 FILE TOO LARGE     - Record position in relative file exceeds disk space
  60 WRITE FILE OPEN    - Tried to open a file for read while open for write
  61 FILE NOT OPEN      - Tried to access a file that is not open
  62 FILE NOT FOUND     - The requested file does not exist
  63 FILE EXISTS        - The filename of the file being created already exists
  64 FILE TYPE MISMATCH - File type does not match file type in directory
  65 NO BLOCK           - B-A command fail (TR,BL=next free block, 00,00=None)
  66 ILLEGAL TRACK AND SECTOR - Illegal track or block number
  67 ILLEGAL SYSTEM T OR S    - Illegal system track or block
  70 NO CHANNEL         - Too many channels used, or requested channel not free
  71 DIRECTORY ERROR    - BAM messed up (on floppy disk, or in drive RAM)
  72 DISK FULL          - Disk or directory full. Close requires 2 free blocks
  73 CBM DOS V2.6 1541  - Power-up message (note that 73 is also used below)
  73 DOS MISMATCH       - DOS2.X cannot <write> to old DOS1-formatted disks
  74 DRIVE NOT READY    - Disk missing

  10 OPEN 1, 8, 15            ;open the error channel
  20 INPUT# 1, A, B$, T, B    ;read error_code, error_name, track, block
  30 PRINT A, B$, T, B        ;display it
  RUN                         ;start (INPUT works only with line numbers)

  OPEN file_name_field: "[@]0:filename[,file_type,direction]"

  PRG or P - Sequential Program (with BASIC tokens, used for LOAD/SAVE)
  SEQ or S - Sequential Data File (typically containing ASCII text data)
  USR or U - Sequential User File (unspecified content)

  OPEN file_name_field: "filename,L,", record_length

  "P", channel+96, record_lsb, record_msb [,character_position]

  character_position specifies the address (1..size) inside of the record.
  If it is not specified, character_position defaults to 1.
  HOW does that separate between ending chr(0dh) and character_pos ???
  Include the character_position number, when adding fields.   WHY ???

  OPEN file_name_field: "\[n]"

  PRINT# cmd_file_number, "BLOCK-ALLOCATE:drive track block"
  PRINT# cmd_file_number, "BLOCK-FREE:    drive track block"

  PRINT# cmd_file_number, "BLOCK-READ:    data_channel drive track block"
  PRINT# cmd_file_number, "U1:            data_channel drive track block"

  PRINT# cmd_file_number, "BLOCK-WRITE:   data_channel drive track block"
  PRINT# cmd_file_number, "U2:            data_channel drive track block"

  PRINT# cmd_file_number, "BUFFER-POINTER:data_channel location"

  !! When the data is being put into the buffer, a pointer in the DOS keeps
  !! track of how many characters there are, when you perform the BLOCK-WRITE
  !! operation, that pointer is recorded on the disk (WHAT WHERE HOW ???).

  FORMAT FOR BLOCK-EXECUTE:
  PRINT#file#, "B-E: data_channel drive track block"

  MEMORY-READ:
  PRINT#file#, "M-R",addr_lsb,addr_msb

  MEMORY-WRITE:
  PRINT#file#, "M-W", addr_lsb, addr_msb, len, data[len]

  "M-E", addr_lsb, addr_msb  ;jump to addr   Any address in RAM or ROM
  "U3" or "UC"               ;jump to 500h   Buffer 2, Index 00h
  "U4" or "UD"               ;jump to 503h   Buffer 2, Index 03h
  "U5" or "UE"               ;jump to 506h   Buffer 2, Index 06h
  "U6" or "UF"               ;jump to 509h   Buffer 2, Index 09h
  "U7" or "UG"               ;jump to 50Ch   Buffer 2, Index 0Ch
  "U8" or "UH"               ;jump to 50Fh   Buffer 2, Index 0Fh
  "U;" or "UJ"               ;jump to [FFFC] Power-up vector

  Track Numbers  Block Numbers  Total Size (Tracks * Blocks)
  1..17          0..20          17*21=357
  18..24         0..18          7*19=133
  25..30         0..17          6*18=108
  31..35         0..16          5*17=85

  Index  Expl.
  00,01  Track and sector of first directory block   (18,01)
  02     ASCII character "A" indicating 4040 format  (41h)
  03     Null flag for future DOS use.               (00h)
  04-8F  Bit map of available blocks for tracks 1-35

  Index  Expl.
  90-A1  144-161  Disk name 18 characters padded with shifted spaces
  A2-A3  162-163  Disk ID two characters
  A4     164      Shifted space                       (A0h)
  A5-A6  165,166  DOS version "2" and format type "A" (32h,41h)
  A6-A7  Shifted spaces                      (A0h,A0h)
  AB-FF  Nulls, not used                     (00h filled)

  Index  Expl.
  00,01  Track and sector of next directory block
  02-1F  File entry 1
  22-3F  File entry 2
  42-5F  File entry 3
  62-7F  File entry 4
  82-9F  File entry 5
  A2-BF  File entry 6
  C2-DF  File entry 7
  E2-FF  File entry 8

  Index    Expl.
  00       128+type
             File type OR'ed with 80h to indicate properly closed file.
             Types: 0=DELeted, 1=SEQuential, 2=PROGram, 3=USER, 4=RELative
  01,02    Track and sector of 1st data block.
  03-12    File name 16 characters padded with shifted spaces (=A0h).
  ???      Relative file only: track and sector for first side sector block.
  ???      Relative file only: Record size.
  13-1B    Unused (zero filled).
  ???      Track and sector of replacement file when OPEN@ is in effect.
  1C-1D    Number of blocks in file: low byte, high byte.

  00,01  Track and sector of next sequential data block.
  02-FF  254 bytes of data with carriage returns as record terminators.

  00,01  Track and sector of next block in program file.
  02-FF  254 bytes of program info stored in CBM memory format (with key
         words tokenized). End of file is marked by three zero bytes.

  00-FF  Data

  00,01   Track and block of next side sector block.
  02      Side sector number. (0-5)
  03      Record length.
  04-0F   Track and block of side sector number 0-5.
  10-FF   Track and block pointers to 120 data blocks.

  00,01   Track and block of next data block.
  02-FF   254 bytes of data.

  Header:     SYNC, 08, ID1, ID2, TRK, BLK, CHKSUM, GAP1
  Data Field: SYNC, 07, DATA[256], CHKSUM, GAP

  - Original 16bit memory address (typically MEMBOT+1)
  - BASIC line(s)
  - Two zero bytes (End of BASIC program)
  - Binary data (eg. machine code) (if any)

  - 16bit pointer to next line (in respect to original load address)
  - 16bit line number
  - BASIC expressions (consisting of tokens and ascii text)
  - One zero byte (End of line)

  <FILENAME>.<T><NN>

  P - Program file (PRG)
  S - Sequential file (SEQ)
  U - User file (USR)
  D - Deleted file (DEL)
  R - Relative file (REL)

  Index Size Expl.
  00h   07h+1  Image ID "C64File", ended by 00h
  08h   10h+1  Original 16 character C64 Filename, padded with 00h
  19h   01h    Record size for REL files (00h for other files)
  1ah   ...    Original file image with load address (same as .PRG file)

  0000-07FF  Work RAM (2 KBytes)
  0800-17FF  Not used
  1800-180F  I/O - VIA#1 (serial data & control)
  1810-1BFF  Not used
  1C00-1C0F  I/O - VIA#2 (drive data & control)
  1C10-BFFF  Not used
  C000-FFFF  Disk ROM (16 KBytes)

  0000-0103  System Area
  0104-01FF  Stack Area
  0200-02FF  System Area
  0300-03FF  Buffer 0
  0400-04FF  Buffer 1
  0500-05FF  Buffer 2
  0600-06FF  Buffer 3
  0700-07FF  Buffer 4

  PB 7, CB2:  ATN IN
  PB 6,5:     Device address preset switches
  PB 4:       ATN acknowledge OUT
  PB 3:       CLOCK OUT
  PB 2:       CLOCK IN
  PB 1:       DATA OUT
  PB 0:       DATA IN

  PA          data to and from read/write head
  PB 7:       SYNC IN
  PB 6,5:     Bit rate D1 and D0
  PB 4:       WPS - Write Protect Sense (1 = On)
  PB 3:       ACT - LED on drive
  PB 2:       MTR - drive motor
  PB 0,1:     step motor for head movement
  CA 1:       Byte ready
  CA 2:       SOE - Set Overflow Enable for 6502
  CA 3: (CA three?)  read/write

  open 1,x,15:print#1,"m-w" chr$(119) chr$(0) chr$(2) chr$(y+32) chr$(y+64)

  Device   Jumper A/1   Jumper B/2
  8        Don't cut    Don't cut   (default)
  9        Cut          Don't cut
  10       Don't cut    Cut
  11       Cut          Cut

  OPEN 1,8,15,"UI-":CLOSE 1    ;VIC 20 speed
  OPEN 1,8,15,"UI+":CLOSE 1    ;Commodore 64 speed (default)

  Bits Name  Expl.
  8    A     Accumulator
  8    X     Index Register X
  8    Y     Index Register Y
  16   PC    Program Counter
  8    S     Stack Pointer (see below)
  8    P     Processor Status Register (see below)

  Bit  Name  Expl.
  0    C     Carry         (0=No Carry, 1=Carry)
  1    Z     Zero          (0=Nonzero, 1=Zero)
  2    I     IRQ Disable   (0=IRQ Enable, 1=IRQ Disable)
  3    D     Decimal Mode  (0=Normal, 1=BCD Mode for ADC/SBC opcodes)
  4    B     Break Flag    (0=IRQ/NMI, 1=BRK/PHP opcode)
  5    -     Not used      (Always 1)
  6    V     Overflow      (0=No Overflow, 1=Overflow)
  7    N     Negative/Sign (0=Positive, 1=Negative)

  Name           Native   Nocash
  Implied        -        A,X,Y,S,P
  Immediate      #nn      nn
  Zero Page      nn       [nn]
  Zero Page,X    nn,X     [nn+X]
  Zero Page,Y    nn,Y     [nn+Y]
  Absolute       nnnn     [nnnn]
  Absolute,X     nnnn,X   [nnnn+X]
  Absolute,Y     nnnn,Y   [nnnn+Y]
  (Indirect,X)   (nn,X)   [[nn+X]]
  (Indirect),Y   (nn),Y   [[nn]+Y]

  A8        nz----  2   TAY         Transfer Accumulator to Y    Y=A
  AA        nz----  2   TAX         Transfer Accumulator to X    X=A
  BA        nz----  2   TSX         Transfer Stack pointer to X  X=S
  98        nz----  2   TYA         Transfer Y to Accumulator    A=Y
  8A        nz----  2   TXA         Transfer X to Accumulator    A=X
  9A        ------  2   TXS         Transfer X to Stack pointer  S=X

  A9 nn     nz----  2   LDA #nn     Load A with Immediate     A=nn
  A5 nn     nz----  3   LDA nn      Load A with Zero Page     A=[nn]
  B5 nn     nz----  4   LDA nn,X    Load A with Zero Page,X   A=[nn+X]
  AD nn nn  nz----  4   LDA nnnn    Load A with Absolute      A=[nnnn]
  BD nn nn  nz----  4*  LDA nnnn,X  Load A with Absolute,X    A=[nnnn+X]
  B9 nn nn  nz----  4*  LDA nnnn,Y  Load A with Absolute,Y    A=[nnnn+Y]
  A1 nn     nz----  6   LDA (nn,X)  Load A with (Indirect,X)  A=[WORD[nn+X]]
  B1 nn     nz----  5*  LDA (nn),Y  Load A with (Indirect),Y  A=[WORD[nn]+Y]
  A2 nn     nz----  2   LDX #nn     Load X with Immediate     X=nn
  A6 nn     nz----  3   LDX nn      Load X with Zero Page     X=[nn]
  B6 nn     nz----  4   LDX nn,Y    Load X with Zero Page,Y   X=[nn+Y]
  AE nn nn  nz----  4   LDX nnnn    Load X with Absolute      X=[nnnn]
  BE nn nn  nz----  4*  LDX nnnn,Y  Load X with Absolute,Y    X=[nnnn+Y]
  A0 nn     nz----  2   LDY #nn     Load Y with Immediate     Y=nn
  A4 nn     nz----  3   LDY nn      Load Y with Zero Page     Y=[nn]
  B4 nn     nz----  4   LDY nn,X    Load Y with Zero Page,X   Y=[nn+X]
  AC nn nn  nz----  4   LDY nnnn    Load Y with Absolute      Y=[nnnn]
  BC nn nn  nz----  4*  LDY nnnn,X  Load Y with Absolute,X    Y=[nnnn+X]

  85 nn     ------  3   STA nn      Store A in Zero Page     [nn]=A
  95 nn     ------  4   STA nn,X    Store A in Zero Page,X   [nn+X]=A
  8D nn nn  ------  4   STA nnnn    Store A in Absolute      [nnnn]=A
  9D nn nn  ------  5   STA nnnn,X  Store A in Absolute,X    [nnnn+X]=A
  99 nn nn  ------  5   STA nnnn,Y  Store A in Absolute,Y    [nnnn+Y]=A
  81 nn     ------  6   STA (nn,X)  Store A in (Indirect,X)  [[nn+x]]=A
  91 nn     ------  6   STA (nn),Y  Store A in (Indirect),Y  [[nn]+y]=A
  86 nn     ------  3   STX nn      Store X in Zero Page     [nn]=X
  96 nn     ------  4   STX nn,Y    Store X in Zero Page,Y   [nn+Y]=X
  8E nn nn  ------  4   STX nnnn    Store X in Absolute      [nnnn]=X
  84 nn     ------  3   STY nn      Store Y in Zero Page     [nn]=Y
  94 nn     ------  4   STY nn,X    Store Y in Zero Page,X   [nn+X]=Y
  8C nn nn  ------  4   STY nnnn    Store Y in Absolute      [nnnn]=Y

  48        ------  3   PHA         Push accumulator on stack        [S]=A
  08        ------  3   PHP         Push processor status on stack   [S]=P
  68        nz----  4   PLA         Pull accumulator from stack      A=[S]
  28        nzcidv  4   PLP         Pull processor status from stack P=[S]

  69 nn     nzc--v  2   ADC #nn     Add Immediate           A=A+C+nn
  65 nn     nzc--v  3   ADC nn      Add Zero Page           A=A+C+[nn]
  75 nn     nzc--v  4   ADC nn,X    Add Zero Page,X         A=A+C+[nn+X]
  6D nn nn  nzc--v  4   ADC nnnn    Add Absolute            A=A+C+[nnnn]
  7D nn nn  nzc--v  4*  ADC nnnn,X  Add Absolute,X          A=A+C+[nnnn+X]
  79 nn nn  nzc--v  4*  ADC nnnn,Y  Add Absolute,Y          A=A+C+[nnnn+Y]
  61 nn     nzc--v  6   ADC (nn,X)  Add (Indirect,X)        A=A+C+[[nn+X]]
  71 nn     nzc--v  5*  ADC (nn),Y  Add (Indirect),Y        A=A+C+[[nn]+Y]

  E9 nn     nzc--v  2   SBC #nn     Subtract Immediate      A=A+C-1-nn
  E5 nn     nzc--v  3   SBC nn      Subtract Zero Page      A=A+C-1-[nn]
  F5 nn     nzc--v  4   SBC nn,X    Subtract Zero Page,X    A=A+C-1-[nn+X]
  ED nn nn  nzc--v  4   SBC nnnn    Subtract Absolute       A=A+C-1-[nnnn]
  FD nn nn  nzc--v  4*  SBC nnnn,X  Subtract Absolute,X     A=A+C-1-[nnnn+X]
  F9 nn nn  nzc--v  4*  SBC nnnn,Y  Subtract Absolute,Y     A=A+C-1-[nnnn+Y]
  E1 nn     nzc--v  6   SBC (nn,X)  Subtract (Indirect,X)   A=A+C-1-[[nn+X]]
  F1 nn     nzc--v  5*  SBC (nn),Y  Subtract (Indirect),Y   A=A+C-1-[[nn]+Y]

  29 nn     nz----  2   AND #nn     AND Immediate      A=A AND nn
  25 nn     nz----  3   AND nn      AND Zero Page      A=A AND [nn]
  35 nn     nz----  4   AND nn,X    AND Zero Page,X    A=A AND [nn+X]
  2D nn nn  nz----  4   AND nnnn    AND Absolute       A=A AND [nnnn]
  3D nn nn  nz----  4*  AND nnnn,X  AND Absolute,X     A=A AND [nnnn+X]
  39 nn nn  nz----  4*  AND nnnn,Y  AND Absolute,Y     A=A AND [nnnn+Y]
  21 nn     nz----  6   AND (nn,X)  AND (Indirect,X)   A=A AND [[nn+X]]
  31 nn     nz----  5*  AND (nn),Y  AND (Indirect),Y   A=A AND [[nn]+Y]

  49 nn     nz----  2   EOR #nn     XOR Immediate      A=A XOR nn
  45 nn     nz----  3   EOR nn      XOR Zero Page      A=A XOR [nn]
  55 nn     nz----  4   EOR nn,X    XOR Zero Page,X    A=A XOR [nn+X]
  4D nn nn  nz----  4   EOR nnnn    XOR Absolute       A=A XOR [nnnn]
  5D nn nn  nz----  4*  EOR nnnn,X  XOR Absolute,X     A=A XOR [nnnn+X]
  59 nn nn  nz----  4*  EOR nnnn,Y  XOR Absolute,Y     A=A XOR [nnnn+Y]
  41 nn     nz----  6   EOR (nn,X)  XOR (Indirect,X)   A=A XOR [[nn+X]]
  51 nn     nz----  5*  EOR (nn),Y  XOR (Indirect),Y   A=A XOR [[nn]+Y]

  09 nn     nz----  2   ORA #nn     OR Immediate       A=A OR nn
  05 nn     nz----  3   ORA nn      OR Zero Page       A=A OR [nn]
  15 nn     nz----  4   ORA nn,X    OR Zero Page,X     A=A OR [nn+X]
  0D nn nn  nz----  4   ORA nnnn    OR Absolute        A=A OR [nnnn]
  1D nn nn  nz----  4*  ORA nnnn,X  OR Absolute,X      A=A OR [nnnn+X]
  19 nn nn  nz----  4*  ORA nnnn,Y  OR Absolute,Y      A=A OR [nnnn+Y]
  01 nn     nz----  6   ORA (nn,X)  OR (Indirect,X)    A=A OR [[nn+X]]
  11 nn     nz----  5*  ORA (nn),Y  OR (Indirect),Y    A=A OR [[nn]+Y]

  C9 nn     nzc---  2   CMP #nn     Compare A with Immediate     A-nn
  C5 nn     nzc---  3   CMP nn      Compare A with Zero Page     A-[nn]
  D5 nn     nzc---  4   CMP nn,X    Compare A with Zero Page,X   A-[nn+X]
  CD nn nn  nzc---  4   CMP nnnn    Compare A with Absolute      A-[nnnn]
  DD nn nn  nzc---  4*  CMP nnnn,X  Compare A with Absolute,X    A-[nnnn+X]
  D9 nn nn  nzc---  4*  CMP nnnn,Y  Compare A with Absolute,Y    A-[nnnn+Y]
  C1 nn     nzc---  6   CMP (nn,X)  Compare A with (Indirect,X)  A-[[nn+X]]
  D1 nn     nzc---  5*  CMP (nn),Y  Compare A with (Indirect),Y  A-[[nn]+Y]
  E0 nn     nzc---  2   CPX #nn     Compare X with Immediate     X-nn
  E4 nn     nzc---  3   CPX nn      Compare X with Zero Page     X-[nn]
  EC nn nn  nzc---  4   CPX nnnn    Compare X with Absolute      X-[nnnn]
  C0 nn     nzc---  2   CPY #nn     Compare Y with Immediate     Y-nn
  C4 nn     nzc---  3   CPY nn      Compare Y with Zero Page     Y-[nn]
  CC nn nn  nzc---  4   CPY nnnn    Compare Y with Absolute      Y-[nnnn]

  24 nn     xz---x  3   BIT nn      Bit Test   A AND [nn], N=[nn].7, V=[nn].6
  2C nn nn  xz---x  4   BIT nnnn    Bit Test   A AND [..], N=[..].7, V=[..].6

  E6 nn     nz----  5   INC nn      Increment Zero Page    [nn]=[nn]+1
  F6 nn     nz----  6   INC nn,X    Increment Zero Page,X  [nn+X]=[nn+X]+1
  EE nn nn  nz----  6   INC nnnn    Increment Absolute     [nnnn]=[nnnn]+1
  FE nn nn  nz----  7   INC nnnn,X  Increment Absolute,X   [nnnn+X]=[nnnn+X]+1
  E8        nz----  2   INX         Increment X            X=X+1
  C8        nz----  2   INY         Increment Y            Y=Y+1

  C6 nn     nz----  5   DEC nn      Decrement Zero Page    [nn]=[nn]-1
  D6 nn     nz----  6   DEC nn,X    Decrement Zero Page,X  [nn+X]=[nn+X]-1
  CE nn nn  nz----  6   DEC nnnn    Decrement Absolute     [nnnn]=[nnnn]-1
  DE nn nn  nz----  7   DEC nnnn,X  Decrement Absolute,X   [nnnn+X]=[nnnn+X]-1
  CA        nz----  2   DEX         Decrement X            X=X-1
  88        nz----  2   DEY         Decrement Y            Y=Y-1

  0A        nzc---  2   ASL A       Shift Left Accumulator   SHL A
  06 nn     nzc---  5   ASL nn      Shift Left Zero Page     SHL [nn]
  16 nn     nzc---  6   ASL nn,X    Shift Left Zero Page,X   SHL [nn+X]
  0E nn nn  nzc---  6   ASL nnnn    Shift Left Absolute      SHL [nnnn]
  1E nn nn  nzc---  7   ASL nnnn,X  Shift Left Absolute,X    SHL [nnnn+X]

  4A        0zc---  2   LSR A       Shift Right Accumulator  SHR A
  46 nn     0zc---  5   LSR nn      Shift Right Zero Page    SHR [nn]
  56 nn     0zc---  6   LSR nn,X    Shift Right Zero Page,X  SHR [nn+X]
  4E nn nn  0zc---  6   LSR nnnn    Shift Right Absolute     SHR [nnnn]
  5E nn nn  0zc---  7   LSR nnnn,X  Shift Right Absolute,X   SHR [nnnn+X]

  2A        nzc---  2   ROL A       Rotate Left Accumulator  RCL A
  26 nn     nzc---  5   ROL nn      Rotate Left Zero Page    RCL [nn]
  36 nn     nzc---  6   ROL nn,X    Rotate Left Zero Page,X  RCL [nn+X]
  2E nn nn  nzc---  6   ROL nnnn    Rotate Left Absolute     RCL [nnnn]
  3E nn nn  nzc---  7   ROL nnnn,X  Rotate Left Absolute,X   RCL [nnnn+X]

  6A        nzc---  2   ROR A       Rotate Right Accumulator RCR A
  66 nn     nzc---  5   ROR nn      Rotate Right Zero Page   RCR [nn]
  76 nn     nzc---  6   ROR nn,X    Rotate Right Zero Page,X RCR [nn+X]
  6E nn nn  nzc---  6   ROR nnnn    Rotate Right Absolute    RCR [nnnn]
  7E nn nn  nzc---  7   ROR nnnn,X  Rotate Right Absolute,X  RCR [nnnn+X]

  4C nn nn  ------  3   JMP nnnn    Jump Absolute              PC=nnnn
  6C nn nn  ------  5   JMP (nnnn)  Jump Indirect              PC=WORD[nnnn]
  20 nn nn  ------  6   JSR nnnn    Jump and Save Return Addr. [S]=PC+2,PC=nnnn
  40        nzcidv  6   RTI         Return from BRK/IRQ/NMI    P=[S], PC=[S]
  60        ------  6   RTS         Return from Subroutine     PC=[S]+1

  10 dd     ------  2** BPL/JNS disp          ;N=0 (plus/positive)
  30 dd     ------  2** BMI/JS  disp          ;N=1 (minus/negative/signed)
  50 dd     ------  2** BVC/JNO disp          ;V=0 (no overflow)
  70 dd     ------  2** BVS/JO  disp          ;V=1 (overflow)
  90 dd     ------  2** BCC/BLT/JNC/JB  disp  ;C=0 (less/below/no carry)
  B0 dd     ------  2** BCS/BGE/JC/JAE  disp  ;C=1 (above/greater/equal/carry)
  D0 dd     ------  2** BNE/BZC/JNZ/JNE disp  ;Z=0 (not zero/not equal)
  F0 dd     ------  2** BEQ/BZS/JZ/JE   disp  ;Z=1 (zero/equal)

  00        ---1--  7   BRK   Force Break B=1 [S]=PC+1,[S]=P,I=1,PC=[FFFE]
  --        ---1--  ??  /IRQ  Interrupt   B=0 [S]=PC,[S]=P,I=1,PC=[FFFE]
  --        ---1--  ??  /NMI  NMI         B=0 [S]=PC,[S]=P,I=1,PC=[FFFA]
  --        ---1--  T+6 /RESET Reset      PC=[FFFC],I=1

  IRQs are executed whenever "/IRQ=LOW AND I=0".
  NMIs are executed whenever "/NMI changes from HIGH to LOW".

  18        --0---  2   CLC         Clear carry flag            C=0
  58        ---0--  2   CLI         Clear interrupt disable bit I=0
  D8        ----0-  2   CLD         Clear decimal mode          D=0
  B8        -----0  2   CLV         Clear overflow flag         V=0
  38        --1---  2   SEC         Set carry flag              C=1
  78        ---1--  2   SEI         Set interrupt disable bit   I=1
  F8        ----1-  2   SED         Set decimal mode            D=1

  EA        ------  2   NOP         No operation                No operation

  87 nn     ------  3   SAX nn      STA+STX  [nn]=A AND X
  97 nn     ------  4   SAX nn,Y    STA+STX  [nn+Y]=A AND X
  8F nn nn  ------  4   SAX nnnn    STA+STX  [nnnn]=A AND X
  83 nn     ------  6   SAX (nn,X)  STA+STX  [WORD[nn+X]]=A AND X
  A7 nn     nz----  3   LAX nn      LDA+LDX  A,X=[nn]
  B7 nn     nz----  4   LAX nn,Y    LDA+LDX  A,X=[nn+Y]
  AF nn nn  nz----  4   LAX nnnn    LDA+LDX  A,X=[nnnn]
  A3 nn     nz----  6   LAX (nn,X)  LDA+LDX  A,X=[WORD[nn+X]]
  B3 nn     nz----  5*  LAX (nn),Y  LDA+LDX  A,X=[WORD[nn]+Y]

  00+yy        nzc---  SLO op   ASL+ORA   op=op SHL 1 // A=A OR op
  20+yy        nzc---  RLA op   ROL+AND   op=op RCL 1 // A=A AND op
  40+yy        nzc---  SRE op   LSR+EOR   op=op SHR 1 // A=A XOR op
  60+yy        nzc--v  RRA op   ROR+ADC   op=op RCR 1 // A=A+op+cy
  C0+yy        nzc---  DCP op   DEC+CMP   op=op-1     // A-op
  E0+yy        nzc--v  ISC op   INC+SBC   op=op+1     // A=A-op-(1-cy)

  07+xx nn        5    nn       [nn]
  17+xx nn        6    nn,X     [nn+X]
  03+xx nn        8    (nn,X)   [WORD[nn+X]]
  13+xx nn        8    (nn),Y   [WORD[nn]+Y]
  0F+xx nn nn     6    nnnn     [nnnn]
  1F+xx nn nn     7    nnnn,X   [nnnn+X]
  1B+xx nn nn     7    nnnn,Y   [nnnn+Y]

  0B nn     nzc---  2  ANC #nn          AND+ASL  A=A AND nn, C=N ;bit7 to carry
  2B nn     nzc---  2  ANC #nn          AND+ROL  A=A AND nn, C=N ;same as above
  4B nn     nzc---  2  ALR #nn          AND+LSR  A=(A AND nn) SHR 1
  6B nn     nzc--v  2  ARR #nn          AND+ROR  A=(A AND nn), V=Overflow(A+A),
                                                 A=A/2+C*80h, C=A.Bit6
  CB nn     nzc---  2  AXS #nn          CMP+DEX  X=(X AND A)-nn
  EB nn     nzc--v  2  SBC #nn          SBC+NOP  A=A-nn         cy?
  BB nn nn  nz----  4* LAS nnnn,Y       LDA+TSX  A,X,S = [nnnn+Y] AND S

  xx        ------  2   NOP        (xx=1A,3A,5A,7A,DA,FA)
  xx nn     ------  2   NOP #nn    (xx=80,82,89,C2,E2)
  xx nn     ------  3   NOP nn     (xx=04,44,64)
  xx nn     ------  4   NOP nn,X   (xx=14,34,54,74,D4,F4)
  xx nn nn  ------  4   NOP nnnn   (xx=0C)
  xx nn nn  ------  4*  NOP nnnn,X (xx=1C,3C,5C,7C,DC,FC)
  xx        ------  -   KIL        (xx=02,12,22,32,42,52,62,72,92,B2,D2,F2)

  8B nn     nz----  2  XAA #nn    ((2)) TXA+AND  A=X AND nn
  AB nn     nz----  2  LAX #nn    ((2)) LDA+TAX  A,X=nn
  BF nn nn  nz----  4* LAX nnnn,X       LDA+LDX  A,X=[nnnn+X]
  93 nn     ------  6  AHX (nn),Y ((1))          [WORD[nn]+Y] = A AND X AND H
  9F nn nn  ------  5  AHX nnnn,Y ((1))          [nnnn+Y] = A AND X AND H
  9C nn nn  ------  5  SHY nnnn,X ((1))          [nnnn+X] = Y AND H
  9E nn nn  ------  5  SHX nnnn,Y ((1))          [nnnn+Y] = X AND H
  9B nn nn  ------  5  TAS nnnn,Y ((1)) STA+TXS  S=A AND X  // [nnnn+Y]=S AND H

 AHX {adr} = stores A&X&H into {adr}
 SHX {adr} = stores X&H into {adr}
 SHY {adr} = stores Y&H into {adr}

  65XX-style    80XX-style         Expl.
  .native       .nocash            select native or nocash syntax
  *=$c100       org 0c100h         sets the assumed origin in memory
  *=*+8         org $+8            increments origin, does NOT produce data
  label         label:             sets a label equal to the current address
  label=$dc00   label equ 0dc00h   assigns a value or address to label
  .by $00       db 00h             defines a (list of) byte(s) in memory
  .byt $00      defb 00h           same as .by and db
  .wd $0000     dw 0000h           defines a (list of) word(s) in memory
  .end          end                indicates end of source code file
  |nn           [|nn]              force 16bit "00NN" instead 8bit "NN"
  #<nnnn        nnnn AND 0FFh      isolate lower 8bits of 16bit value
  #>nnnn        nnnn DIV 100h      isolate upper 8bits of 16bit value

  .65xx       Select 6502 Instruction Set
  .nes        Create NES ROM-Image with .NES extension
  .c64_prg    Create C64 file with .PRG extension/stub/fixed entry
  .c64_p00    Create C64 file with .P00 extension/stub/fixed entry/header
  .vic20_prg  Create VIC20/C64 file with .PRG extension/stub/relocated entry
  end entry   End of Source, the parameter specifies the entrypoint

 6501   Some sort of 6502 prototype
 6502   Used in the CBM floppies and some other 8 bit computers.
 6507   Used in Atari 2600, 28pins (only 13 address lines, no /IRQ, no /NMI).
 6510   Used in C64, with built-in 6bit I/O port.
 7501   Used in C16,C116,Plus/4, with built-in 7bit I/O Port, without /NMI pin.
 8500   Used in C64-II, with different pin-outs.
 8501   Same as 7501
 8502   Used in C128s.

 65C02  Extension of the 6502, used in the C16, C116 and the Plus/4 computers?
 65SC02 Small version of the 65C02 which lost a few opcodes again.
 65CE02 Extension of the 65C02, used in the C65.
 65816  Extended 6502 with new opcodes and 16 bit operation modes.
 2A03   Nintendo NES/Famicom, modified 6502 with built-in sound controller.

  C64   Z80   Opcode    Disassembled      Comment
  1000  0000  00        nop               ;\the Commodore Z80 needs three NOPs
  1001  0001  00        nop               ; to stabilize after mode switching
  1002  0002  00        nop               ;/
  1003  0003  21 02 F5  ld   hl,0F502h    ;\the actual Z80 'program' increment
  1006  0006  34        inc  (hl)         ;/a byte in VRAM (C64 address=0502h)
  1007  0007  3E 01     ld   a,01h        ;\turn off Z80 again by I/O port
  1009  0009  32 00 CE  ld   (0CE00h),a   ;/(C64 address=DE00h)
  100C  000C  00        nop               ;\
  100D  000D  00        nop               ; again three NOPs to 'destabilize'
  100E  000E  00        nop               ;/
  100F  000F  C3        jp   0000h        ;-Huh? Should never execute this...

  10 poke 56333,127   :rem [DC0Dh]=7Fh, turn off 6510 irq's
  20 poke 56832,00    :rem [DE00h]=00h, turn on z80 card & execute Z80 code
  30 poke 56333,129   :rem [DC0Dh]=81h, turn on 6510 irq's when z80 done

  Pin Name      Expl.
  1   Switch 0  Joystick Up
  2   Switch 1  Joystick Down
  3   Switch 2  Joystick Left, or Paddle X-Button
  4   Switch 3  Joystick Right, or Paddle Y-Button
  5   POTY      Paddle Y-Axis
  6   Switch 4  Joystick Fire, or Lightpen (Port 1 only)
  7   +5V       Power Supply (max 50mA)
  8   GND       Ground
  9   POTX      Paddle X-Axis

    Pin Expl.      Pin Expl.      Pin Expl.      Pin Expl.
    1   GND        12   BA        A   GND         N   A9
    2   +5V        13   /DMA      B   /ROMH       P   A8
    3   +5V        14   D7        C   /RESET      R   A7
    4   /IRQ       15   D6        D   /NMI        S   A6
    5   R/W        16   D5        E   02          T   A5
    6   Dot Clock  17   D4        F   A15         U   A4
    7   I/O1       18   D3        H   A14         V   A3
    8   /GAME      19   D2        J   A13         W   A2
    9   /EXROM     20   D1        K   A12         X   A1
   10   I/O2       21   D0        L   A11         Y   A0
   11   /ROML      22   GND       M   A10         Z   GND

  Pin  Expl.                 ++ ++
  1    Luminance           /  +-+  \
  2    GND                +  8   7  +
  3    Audio Out          | 3  6  1 |
  4    Video Out          +  5   4  +
  5    Audio In            \   2   /
  6    Chrominance           +---+
 (7)   N.C.
 (8)   +5V DC

  Pin Expl.                  ++ ++
  1   Serial /SRQ In       /  +-+  \
  2   GND                 +  5   1  +
  3   Serial ATN Out      |    6    |
  4   Serial CLK In/Out   +  4   2  +
  5   Serial Data In/Out   \   3   /
  6   /RESET                 +---+

  Pin  Expl.
  A-1  GND
  B-2  +5V DC
  C-3  Cassette Motor (WHAT=On ???) (+9V UNREG DC ?)
  D-4  Cassette Read
  E-5  Cassette Write
  F-6  Cassette Sense (Switch PLAY Pressed ???, WHAT=Yes ???)

  Pin  Expl.               Pin  Expl.
  1    GND                 A    GND
  2    +5V DC (max 100 mA) B    /FLAG2
  3    /RESET              C    PB0
  4    CNT1                D    PB1
  5    SP1                 E    PB2
  6    CNT2                F    PB3
  7    SP2                 H    PB4
  8    /PC2                J    PB5
  9    SER. ATN OUT        K    PB6
  10   9V AC1 (max 100 mA) L    PB7
  11   9V AC2 (max 100 mA) M    PA2
  12   GND                 N    GND

  Pin    Expl.               ++ ++
  1      GND               /  +-+  \
  2      GND (or N.C.)    +  7   6  +
  3      GND              | 3     1 |
  4      +5V DC           +  5   4  +
  5      +5V DC            \   2   /
  6      +/-9V AC1           +---+
  7      +/-9V AC2

  Name    Pin                         Pin       Name
  PA2     USR.M     ----------------- PRN.1     /STROBE
  PB0-7   USR.C-L   ----------------- PRN.2-9   DATA0-7
  FLAG    USR.B     ----------------- PRN.11    BUSY
  GND     USR.A,N   ----------------- PRN.19-24 GND
  GND     USR.A,N   ----------------- PRN.14    /AUTOLF
  /INTRES EXP.C     ----------------- PRN.16/31 /INIT
  /EXROM  EXP.9     ---|>|---+---+--- PRN.17/36 /SELECT
  +5VDC   EXP.2     --[3K3]--'   '--- ROM.20    /CS
  /ROML   EXP.11    ----------------- ROM.22    /OE
  GND     EXP.1     ----------------- ROM.14    GND
  +5VDC   EXP.2     ----------------- ROM.1,26-28  A13-15,VCC
  D0-7    EXP.21-14 ----------------- ROM.11-13,15-19  D0-7
  A0-12   EXP.Y-K   ----------------- ROM.10-3,25,24,21,23,2  A0-12

  1E 81 00 00 C3 C2 CD 38 30 A9 1B 8D 11 D0 A9 08
  8D 16 D0 A9 04 09 10 8D 18 D0 A9 03 8D 00 DD A9
  00 8D 15 D0 A9 00 A9 02 8D 20 D0 8D 21 D0 A9 01
  A2 00 9D 00 D8 9D 00 D9 9D 00 DA 9D 00 DB E8 D0
  F1 A9 20 A2 00 9D 00 04 9D 00 05 9D 00 06 9D 00
  07 E8 D0 F1 A9 00 85 0C 85 0D 60 48 C9 0D D0 07
  A9 00 85 0C 4C 95 80 C9 0A D0 05 E6 0D 4C 95 80
  A9 00 85 0B A5 0D 0A 0A 65 0D 0A 0A 26 0B 0A 26
  0B 65 0C 85 0A A9 04 65 0B 85 0B 68 48 29 3F A2
  00 81 0A E6 0C 68 60 68 85 08 68 85 09 E6 08 D0
  02 E6 09 A2 00 A1 08 E6 08 D0 02 E6 09 C9 00 F0
  06 20 5B 80 4C A3 80 6C 08 00 A9 3B 8D 02 DD A9
  00 8D 03 DD 60 A9 04 2C 00 DD D0 FB AE 01 DD 2C
  00 DD F0 FB 8A 60 A0 00 A9 04 2C 00 DD D0 FB AD
  01 DD 91 02 C8 A9 04 2C 00 DD F0 FB AD 01 DD 91
  02 C8 D0 E4 E6 03 60 A9 00 A8 99 02 00 99 00 02
  99 00 03 C8 D0 F4 A9 3C 85 B2 A9 03 85 B3 A9 A0
  8D 84 02 A9 08 8D 82 02 A9 04 8D 88 02 60 A9 E7
  85 01 A9 2F 85 00 A2 00 8E 16 D0 20 A3 FD 20 F7
  80 20 15 FD 20 5B FF 58 4C 3B 81 20 53 E4 20 BF
  E3 20 22 E4 A2 FB 9A D0 00 A2 80 4C 4E 81 8A 20
  87 81 86 2D 84 2E A9 76 A0 A3 20 1E AB 20 59 A6
  20 33 A5 A9 04 85 C6 A2 09 BD 7D 81 9D 77 02 CA
  10 F7 A9 A4 48 A9 7F 48 A9 04 4C 7B 02 52 55 4E
  0D 2C 00 DD F0 FB 60 08 78 20 BA 80 A9 05 8D 20
  D0 20 C5 80 85 02 20 C5 80 85 03 20 C5 80 85 04
  20 C5 80 85 05 20 C5 80 85 06 20 C5 80 85 07 A9
  00 8D 20 D0 20 D6 80 C6 05 D0 F9 A9 04 2C 00 DD
  D0 FB A9 0F 8D 20 D0 A6 02 A4 03 28 60

  C64 Port 1 ----|>|----+---- Joystick Switch
  C64 Port 2 ----|>|---/
  C64 Ground ---------------- Joystick Ground