Toshiba HX-31
This page was last modified 01:08, 18 January 2021 by Mars2000you. Based on work by Gdx and Rderooy.




The HX-31 looks identical to the HX-30 with its black case, but it has more RAM and a built-in firmware. It is not possible to add an RS-232C interface. This machine was released for the Japanese market with the "Pasopia IQ" label.

Although it's a MSX1 computer, it can use a part of the MSX memory to create a Memory Disk (feature generally reserved for MSX2 and higher computers), just like the HX-32.

Brand Toshiba
Model HX-31
Year 1985
Region Japan
Launch price ¥49,800
RAM 64kB
Media Cartridges
Video  ? Toshiba T6950
Audio PSG (YM2149F)
Chipset  ? Toshiba TCX-1012/TCX-1008
Keyboard layout QWERTY/JIS
Extras firmware (Japanese Word Processor - Kanji-Kun v.2.2), MemoryDisk BASIC, Printer BASIC
Emulation ROM dump needed. See this thread for details


The built-in firmware is a Japanese Word Processor. From BASIC, it can be launched with CALL JWP or _JWP. It includes the additional BASIC instructions for Memory Disk and printer.

The Japanese Word Processor is version 2.2 of the same software available in versions 2.0 and 2.5 on the Toshiba HX-2x series.

However, you need to have the HX-M200 Kanji-ROM Level 1 in one of the cartridge slots.

It is possible to use other Kanji Roms, but if you use the Sony HBI-K16 Kanji-ROM Level 1, CALL JWP leads to a I/O device error. To bypass this problem, an addendum to the manual of the Sony cartridge gives the solution:

10 FOR I = &H9080 TO &H9120 : POKE I, &HC9 : NEXT I

The main menu includes 6 options:

  • Japanese Word Processor - if you press twice on ESC, you can access many WP features
  • Conversion Tools
  • Load and Save
  • Printer Settings and Print
  • Full Book Deletion
  • Tools for Idioms and Short Sentences

CTRL+STOP can be used to go back to the previous menu or the main menu, except if you are in the first option. You need to reboot to quit the Japanese Word Processor.


Toshiba HX-31 box
Toshiba HX-30/31/32 manuals
Toshiba HX-31
Toshiba HX-31 back
Toshiba HX-31 label
Toshiba HX-31 right side


The HX-31 is a MSX1 computer with 2 cartridge slots (one at the top, one at the back) and a Z80A from Sharp (LH-0080A). The 2 joystick ports are located on the right side of the computer.