Popolon Musical Memory Mapper
This page was last modified 15:19, 23 October 2020 by Gdx. Based on work by Mars2000you and Grauw and others.



The Musical Memory Mapper (MMM) cartridge is a standard 1024kB external memory extension for MSX1, MSX2, MSX2 + and MSX Turbo R sold by Popolon and Repro Factory (2013~2016).

Additionally it has the following features:

  • A SN76489AN sound chip used in various game consoles of the 80s built-in.
  • A write protection function and the ability to manage its memory regardless of other memory mappers.
  • MMM initializes Memory Mapper pages on each memory bank of 0000h~3FFFh, 4000h~7FFFh, 8000h~BFFFh and C000h~FFFFh in the order 3, 2, 1, 0 at MSX startup to provide compatibility with MSX1.

Many memory mapper cartridges support reading the mapper registers to support some non-standard compliant software which attempts to do so. The first version of MMM is a memory mapper does not provide this ability. The second version of MMM (chrome case) does allow mapper read-back to be enabled. By default it is disabled.

The cartridge contacts are gold plated. The price is around €42.


Musical Memory Mapper
MMM v1.2 PCB with bus connector
MMM v1.3 PCB


  • RAM: 1024kB
    • Memory mapper with MSX1s support and configurable to specific 16K mapper
  • SN76489AN inside (I/O ports: 3Fh)
    • Disabled by default

Important: Since the v1.2 it's possible to read the Memory Mapper registers when the resistor INT-2 (10KΩ) is soldered. On the v1.3, this is the jumper INT. That must be removed if another 2MB or 4MB Memory Mapper with readable registers is used at same time.

See the manual for more information.

Minimum System Requirements

  • MSX1 computer, one free slot cartridge


  • BMMS (Bigger Memory Mapper Selector)
  • CHKMEM.BIN (Utility that displays the slot of RAM, memory mapper and MegaRAM by LARK)
  • LRT2MSX.COM (included in SGTOOL.ZIP) allows to run Loretta no Shouzou (SG-1000).
  • Mapper info (by Yukke)
  • MEGA16.COM (Megarom with ASC16 mapper loader)
  • MEMTEST.COM (RAM of memory mapper tester by Masatoshi Fujimoto)
  • ROM2MMM.COM (MSX ROM loader by GDX)
  • SG1000.COM (Sega SG-1000 ROM loader by GDX)
  • VGMPLAY.COM (Music player for SN76489 and many other chips by Grauw)
  • TESTMAP.COM (Memory mapper RAM tester by Marteen)
  • SofaRom (MegaROM and ROM loader by Louthrax)

External Links