MAX Machine and Commodore 64

The MAX Machine is essentially a half of the Commodore 64, with all unnecessary chips stripped out for cost purposes. The division of the chips strongly suggests that these two machines were in fact designed at the same time, so that as much chips as possible could be removed while still retaining the game console functionality.

The MAX Machine retains these characteristics of the Commodore 64:

  • 6510 processor.
  • VIC-II graphic chip (only NTSC version for Japanese market).
  • SID sound chip.
  • First CIA chip, controlling joysticks and keyboard.
  • Cassette port.
  • Expansion port.
  • TV port.

The following are missing from the MAX Machine:

  • Second CIA chip, which in the C64 controls the user port and IEC port.
  • User port.
  • IEC port.
  • Monitor port.

The MAX Machine has only 2 kilobytes of memory, compared to 64 kilobytes of Commodore 64. Additional 2 kilobytes can be supplied on the cartridge, making a total of 4 kB memory. Because the machine has no built-in ROMs, the software must reside on the cartridge as well.

The memory map is also a bit different. Because the RAM is limited and there is no character ROM, the VIC-II graphics chip is allowed to access a portion of the cartridge ROM. The memory area from $F000-$FFFF is mapped into VIC address space at $3000-$3FFF. This is necessary because the VIC can only access 16 kB of memory, so this mapping is needed for it to see both the internal RAM starting at $0000 and the cartridge ROM. This space is meant for storing character data, sprite shapes and so on. Note that this is different from C64 arrangement where the VIC sees the character ROM at $1000-$1FFF; also on the C64 the VIC never gets access to external memory.

The MAX Machine memory map is emulated (with some caveats) on the Commodore 64 when an MAX Machine cartridge is inserted.


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