Category:RAM Expansions
This page was last modified 08:47, 3 November 2018 by Gdx. Based on work by Rderooy and Grauw and others.


8-48 kB RAM expansion cartridges

These cartridges were designed to upgrade a MSX1 with less then 64kB of memory. They have a hardcoded base-address, and as such can only be used in very specific settings.

MSX RAM Expansion.png

As you can see in the above diagram, a 16kB MSX can be expanded with a 16, 48 or 64kB RAM expansion. A 8kB RAM expansion would overlap with the systems base memory and is effectively pointless. As the memory needs to be contiguous, the 32kB RAM expansion can only be used in combination with the 16kB expansion.
The diagram shows the base memory in Slot 0 for illustrative purposes as that is the case for most MSX1 systems with less than 64kB of RAM. However, the memory can in reality be located in any slot.

Also, using one of these cartridges, other then the 64kB RAM Expansion, will result in the systems base memory and the expanded memory to be located in different slots. While this is supported in the MSX specification (and some MSX systems even have the internal memory split over two slots), it is known to cause problems with software that blindly assumes that all the RAM will be in a single slot. If your looking to buy a memory expansion, it is recommended that you avoid upgrades of less than 64kB.

Model Capacity Notes
Addcom ADMSM 301 16kB
Addcom ADMSM 302 32kB
Addcom ADMSM 303 48kB
Casio KB-7 8kB Casio PV-7 or Sanno SPCmk-II only
Casio OR-208 8kB Casio PV-7 or Sanno SPCmk-II only
Casio OR-216 16kB
Fujitsu MB22451 16kB Fujitsu FM-X only
General RJ-102 16kB
Mitsubishi ML-16RAM 16kB
National CF-2131 16kB
Neos RM-48 48kB
Philips VU 0031 16kB
Pioneer PX-RA32 32kB
Sanyo MRP-16 16kB
Sony HBM-16 16kB
Toshiba HX-M250 16kB
Yamaha SRE-01 32kB Only for systems with Yamaha 60-pin Expansion slot
Yamaha SRM-01 32kB Only for systems with Yamaha 60-pin Expansion slot
Yamaha URM-01 32kB

64 kB RAM expansion cartridges

These cartridges were designed to upgrade a MSX1 regardless of how much base memory it has to 64kB. They have a hardcoded base address of 0x0000. They cannot however be used to upgrade a MSX2 with 64kB to 128kB.

In effect the memory in these cartridges will overlay the systems internal memory, making the internal memory inaccessible. As the entire 64kB will be in a single slot, they do not suffer from the software compatibility problem where the memory is split over two slots. These cartridges can also be used to diagnose a MSX with suspected bad memory.

Model Capacity Notes
Casio OR-264 64kB
Philips VU 0034 64kB
Sanco Memoire Ram 64Ko 64kB
Sharp-Epcom HB-4100 64kB
Sony HBM-64 64kB
Spectravideo SVI-747 64kB
Toshiba HX-M251 64kB
Walther Miller WM 0587 64kB Dubious manufacturer, avoid!

Memory Mapper expansion cartridges

For more information about how a Memory Mapper works, see Memory Mapper. These expansions are primarily meant for MSX2 and MSX2+ systems. The MSX1 BIOS is not able to initialise them, but you can manually initialise them or some cartridges can self-initialise.

Model Capacity MSX1 7 MHz turbo R Notes
8bits4ever Carnivore 2 1024 kB
8bits4ever MEGA-MAPPER 1, 2 or 4 MB
8bits4ever SD-512 512 kB
Alexey 1024KB Expansion RAM 1024 kB Internal upgrade for selected
Yamaha systems (e.g. CX5MII)
ASCII MEM-768 768 kB
ASCII Nihongo MSX-DOS 2 0, 128 or 256 kB
Classic PC 16MB Expansion Memory 16 MB
Digital KC MSX Memory Mapper 2 MB
Green MSX WBM512 512 kB
GR8NET 1024 kB
Hardware Partners TM 512 kB or 1 MB
HSH RE-512 MM 512 kB
Megaminx Memory Upgrade Board 256 kB Internal upgrade for Panasonic
MFP Extended Memory-2048K 2048 kB
MK Public Domain MSX Memory Mapper 1, 2 or 4 MB
MegaFlashROM SCC+ SD 512 kB
MSX Club Gouda Memory Mapper 1, 2 or 4 MB
MSX Club Gouda Memory Mapper E.M.S. 1, 2 or 4 MB
Padial LPE-4FMB-V8SKP 4096 kB
Padial LPE-4MB-V4SKP 4096 kB
Padial LPE-512KBSRAM-V3 512 kB
Playsoniq 16 MB
Popolon MSX Memory Mapper 1024 kB
Popolon Musical Memory Mapper 1024 kB
R.& J.Jansen Memory Mapper 256/512 256 or 512 kB
Sony HBM-512 512 kB
T.N.S. Addram 4 MB
Tecnobytes Double RAM 4096 kB

Note: ✓ in MSX1 column indicates that the Memory Mapper is able to initialise its pages at start itself.