ASCII MSX-Serial 232
This page was last modified 14:35, 13 January 2022 by Mars2000you. Based on work by Rderooy and Gdx and others.


The ASCII MSX-Serial 232 is a RS-232C interface including a cartridge and a manual. It was only available in Japan. At the time it was marketed as a way to overcome the 1200bps limit of MSX Modem cartridges, or integrated modems. Allowing newer 2400bps external modems to be used. The cartridge itself is limited to 9600 baud.

The adapter provides a DB-25 female port. A cable is not included in the package.

It is just one of three MSX Serial add-on adapters to use RS-232C BIOS 2.0 (the other being the Repro Factory HBI-232MKII and Sony HBI-232). The ROM included in the interface contains also the RS-232C BASIC instructions.

In addition, it is the only MSX serial solution that support DMA (Direct Memory Access). There is a switch on the front of the cartridge to enable or disable the DMA function.

Where MSX serial solutions with BIOS 1.x use IO ports, and only one such adapter may be used at a time, with BIOS 2.0 memory mapped I/O is used, and multiple adapters are allowed.

Model MSX-Serial 232
Year 1989-11
Region Japan
Launch price ¥19,417
Package content Serial Interface adapter
User's Manual
Emulation ROM dump needed. See this thread for details


ASCII MSX-Serial 232
ASCII MSX-Serial 232 packaging
ASCII MSX-Serial 232 - with cable
ASCII MSX-Serial 232 - front of PCB
ASCII MSX-Serial 232 - back of PCB