MEMORY
Color Computers 1 and 2 shipped with 4, 16, 32, or 64KB of RAM depending on options and board.
The Color Computers 1 and 2 were equipped with a Synchronous Address Multiplexer (SAM MC6883) to manage memory configuration and refresh.
Color Computer 3 shipped with 128 or 512KB of RAM depending on options chosen.
The Color Computer 3 custom GIME chip included emulation for the previous generation's SAM chip as well as provided a new Memory Management Unit MMU for working with memory larger than 64KB.
RAM
Random Access Memory
EXPANDED MEMORY MAP
| COCO3 ADDRESS | COCO3 BLOCK | COCO MEMORY ADDRESS | NOTES |
|---|---|---|---|
| 00000 - 5FFFF | 00 - 2F | RAM | 512K Upgrade RAM - unused by BASIC |
| 60000 - 61FFF | 30 | RAM | High Resolution Page 1 |
| 62000 - 63FFF | 31 | RAM | High Resolution Page 2 |
| 64000 - 65FFF | 32 | RAM | High Resolution Page 3 |
| 66000 - 67FFF | 33 | RAM | High Resolution Page 4 |
| 68000 - 69FFF | 34 | RAM | HGET/HPUT Buffer |
| 6A000 - 6BFFF | 35 | RAM | Secondary Stack |
| 6C000 - 6DFFF | 36 | RAM | High Resolution Text Screen RAM |
| 6E000 - 6FFFF | 37 | RAM | Unused by BASIC |
| 70000 - 71FFF | 38 | 0000 - 1FFF | BASIC RAM 8K - 0400 - 05FF 32×16 Text Screen RAM |
| 72000 - 73FFF | 39 | 2000 - 3FFF | BASIC RAM 16K |
| 74000 - 75FFF | 3A | 4000 - 5FFF | BASIC RAM 24K |
| 76000 - 77FFF | 3B | 6000 - 7FFF | BASIC RAM 32K |
| 78000 - 79FFF | 3C | 8000 - 9FFF | Extended Color BASIC ROM (1.0 - 1.1) |
| 7A000 - 7BFFF | 3D | A000 - BFFF | Color BASIC ROM (1.0 - 1.3) :: polcat.asm :: joystk.asm :: newcls |
| 7C000 - 7DFFF | 3E | C000 - DFFF | Disk BASIC ROM (1.0 - 1.1) :: CoCoSDC :: Cartridge ROM Paks |
| 7E000 - 7FFFF | 3F | E000 - FEFF | Super Extended Color BASIC ROM and Easter Egg bitmap |
| 7E000 - 7FFFF | 3F | FF00 - FF03 | MC6821 / MC6822 PIA0 Keyboard IRQ Joystick interface :: keyscn |
| 7E000 - 7FFFF | 3F | FF20 - FF23 | MC6821 / MC6822 PIA1 Cassette, RS-232, IRQ, DAC, MC6847 MC6847T1 VDG, Sound Generator, Drivewire |
| 7E000 - 7FFFF | 3F | FF40 | DSKREG Disk Output Latch |
| 7E000 - 7FFFF | 3F | FF41 | Games Master Cart SN76489AN |
| 7E000 - 7FFFF | 3F | FF42 - FF43 | Becker Port |
| 7E000 - 7FFFF | 3F | FF48 - FF4B | WD1793 FDC Registers Status, Track, Sector, Data |
| 7E000 - 7FFFF | 3F | FF60 - FF62 | TRS-80 Digitizer (26-1195) |
| 7E000 - 7FFFF | 3F | FF68 - FF6B | Deluxe RS-232 Pak (26-2226) |
| 7E000 - 7FFFF | 3F | FF6C - FF6F | Direct Connect Modem Pak (26-2228) |
| 7E000 - 7FFFF | 3F | FF7A - FF7B | Orchestra 90/CC Cartridge (26-3143) |
| 7E000 - 7FFFF | 3F | FF7D - FF7E | Speech/Sound Cartridge (SSC) (26-3144A) |
| 7E000 - 7FFFF | 3F | FF7F | Multi-Pak Interface (MPI) (26-3024, 26-3124, 26-3124A) Slot Select |
| 7E000 - 7FFFF | 3F | FF90 - FFBF | TCC1014 VC2645QC ACVC GIME MMU Palette |
| 7E000 - 7FFFF | 3F | FFC0 - FFDF | MC6883 Synchronous Address Multiplexer SAM |
| 7E000 - 7FFFF | 3F | FFE0 - FFEF | |
| 7E000 - 7FFFF | 3F | FFF0 - FFFF | Motorola MC6809E :: Hitachi HD6309E :: Stacks :: Vectors :: CPUID.cas |
- MMU Block: 8192 bytes
- SAM Page: 32768 bytes
RTS
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