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MA-20 Compatibility List
This page was last modified 11:23, 17 February 2023 by Mars2000you. Based on work by Gdx.

Compatibility list with the MSX2 upgrade cartridge (MA-20 and clones).

Note : The list is non-exhaustive.

Hardware Compatibility

There are a few compatibility problems with some computers, for example the Daewoo DPC-200 (probably a conflict with the Hangul driver ROM) or the Yamaha CX5MII and CX5MII/128 (have an incompatible rom which uses hooks to expand the screen width to 80 columns).

It is meaningless to use this adapter on a MSX2 or higher machine, but if you try that, it will not work on MSX2 or MSX2+, but will on Turbo R:

  • the MA-20 does not work with a MSX2 or MSX2+, because the initializiation routines search for any subrom in any slot. Therefore it calls the subrom of the MA-20 without proper V9938 initialization, which causes the subrom to hang.
  • the reason it is working in a Turbo R is because this machine does not search for a subrom, the slot id of the subrom is hardcoded in the initialization code. Therefore the subrom of the MA-20 is called after the MA-20 mainrom is initialized which works just fine.

Software Compatibility

The original MA-20 replaces the internal Main-ROM with a specific Japanese Main-ROM. Several keys will return bad characters on an non-Japanese MSX. MA-20 clones uses a patched Main-ROM for a local use but it doesn't solve everything.

The main problems of MA-20 are the different I/O ports to access the VDP and the confusion in the MSX standard that is created by the MA-20.

The system variable MNROM (0FCC1h) which comes from the EXPTBL table was used as for MINROM (0FFF7h) which was introduced from MSX2. Normally, bit 7 of the MNROM variable is used to indicate whether Slot 0 is extended or not. As the other bits are reset by the system on initialization and the Main-ROM on MSX1 is supposed to always be in Slot 0 or 0-0, this variable makes it possible to know the Slot of the Main-ROM on MSX1.

From the MSX2, the standard allows the Main-ROM to be moved to another Slot. The system variable MINROM has been added to know this Slot. The MA-20 should therefore have modified only the variable MINROM (0FFF7h) to keep maximum compatibility but, probably to avoid the use of a second monitor, it also writes the slot number of its replacement main-ROM to MNROM (0FCC1h).

Because of this, MSX programs can no longer determine if Primary Slot 0 is extended or not and most MSX1 programs no longer go through the original Bios, which sometimes causes bugs.

Unsupported MSX2 software list:

The games below seem to work although direct access to the VDP seems to occur at least once.

MSX2+ Software Compatibility

Below is MSX2+ Software that does not work on MSX2+ upgrade cartridges.

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