This page was last modified 22:03, 17 January 2021 by Mars2000you. Based on work by Gdx and Rderooy and others.



The ASCII MEM-768 is a 768kB standard Memory Mapper RAM expansion cartridge that was launched in Japan in 1991.

The cartridge can be fairly easily expanded to 1024kB by adding two 128kB RAM chips of the same type, and two capacitors (0.1μF).

In addition, this cartridge has been also designed to allow the addition of a ROM (27C512) containing the MSX-DOS 2 kernel (Disk-ROM v2.20). When adding the MSX-DOS 2 kernel ROM, the jumper "JP1" needs to be shorted. You will also need to add a 0.1μF capacitor at location C3 near the ROM.

Model MEM-768
Year 1991
Region Japan
Launch price ¥30,000
Package content Memory Mapper cartridge
User's Manual
Emulation Not emulated, but various other emulated RAM expansion options are available incl. 512kB, 1MB, 2MB and 4MB.


ASCII MEM-768 box front
ASCII MEM-768 box back
ASCII MEM-768 package
ASCII MEM-768 original PCB
ASCII MEM-768 PCB with 1MB

Minimum System Requirements

  • MSX2 computer, one free slot cartridge

Note: As with all standard Memory Mappers, this cartridge is not supported by MSX1 computers except when used with Nextor or a MSX-DOS2 unbridled (like the Sunrise CF interface). On MSX1 without Nextor, the page order needs to be manually initialised pages from BASIC before it can be used.


  • BMMS (Bigger Memory Mapper Selector)
  • CHKMEM.BIN (Utility that displays the slot of RAM, Memory Mapper and MegaRAM by LARK)
  • Mapper Info (by Yukke)
  • MEGA16.COM (loader for megaroms with 16k mapper)
  • MEMTEST.COM (RAM of Memory Mapper tester by Masatoshi Fujimoto)
  • TESTMAP.COM (RAM of Memory Mapper tester by Marteen)
  • SofaRom (MegaRoms and Roms loader by Louthrax)