Tag: mmu

Replaces the Atari 1200XL's model-specific C060609 memory-management chip with a programmed modern logic device.

The page reported two units in stock on 2026-07-27. This listing is specifically a replacement for Atari part C060609 in socket U14 of a 1200XL. Do not treat the seller's general explanation of MMUs across the Atari 8-bit family as compatibility with other models.

Replaces an Atari ST or Mega ST memory subsystem with a 4 MB expansion and a motherboard-specific adapter.

The Heron board and three current adapters exposed order paths on 2026-07-27. A complete installation requires the Heron plus either the C070789-001 Revision F adapter, the C070523-001 Revision D adapter, or the universal socketed-MMU adapter. C070859-001 Revision 2.0 and C103414-001 adapters were still described as in development. The Shifter must be socketed or desoldered, the original RAM must be disabled, and A9 and WE wires must be connected. This is a skilled mains-exposed internal installation; disconnect power and choose the exact motherboard adapter before ordering.

Combines a Z80 processor with a 20-bit MMU for SC721's 1 MB linear memory.

The project provides firmware, a schematic, Gerbers, PCB design files, and kit or bare-PCB suppliers; an assembled version is not offered. Pair it with SC721 linear memory and do not combine it with the bank-switching SC707 or SC714 memory modules.

Adds an all-RAM 64 KB memory map to the SuperPET's 6809 side so it can run the preserved Super OS/9 port.

RETRO Innovations says kits are available through its online store. This is a specialist assembly kit for a two- or three-board SuperPET, not a general PET memory expansion. Use the published construction steps and preserved software package; TPUG and the former OS/9 rights holder do not provide support.