R. and J.Jansen Memory Mapper 256/512
This page was last modified 20:10, 21 January 2022 by Mars2000you. Based on work by Gdx and TheKid.



The R. & J.Jansen Memory Mapper 256/512 is a standard memory extension of 256 or 512kB that was sold in Netherlands. It was made by son and father R. & J.Jansen.


R. & J.Jansen Memory Mapper
R. & J.Jansen Memory Mapper PCB with 512kB
R. & J.Jansen Memory Mapper box
R. & J.Jansen Memory Mapper box back

Minimum System Requirements

  • MSX2 computer, one free slot cartridge

Note: As all standard Memory Mapper, this cartridge is not supported by MSX1 computers because we need to manually initialize the mapper pages in 3, 2, 1, 0 order at startup. Nextor or a MSX-DOS2 unbridled (like Sunrise CF interface) can allow you to use this expansion on MSX1 without manually initialize the mapper pages.


  • 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)