Toshiba HX-21
This page was last modified 12:56, 20 December 2021 by Gdx. Based on work by Mars2000you and Rderooy.
Toshiba HX-21.jpg




This machine was aimed at the Japanese market - see HX-21 series for the technical details

As for many machines with the "Pasopia IQ" label, the PSG sound output is stereo, with a switch at the back. Although it's a MSX1 computer, it can use a part of the MSX memory to create a RAM-Disk or Memory Disk (feature generally reserved for computers with version 2.1 of MSX-BASIC).

An RS-232C interface with its switch can be added by soldering the connector on the power supply board, then adding the switch and the same RS-232C board from the HX-22. You also need to add a connector on the power supply board or solder the wires directly.

A kit was sold for the HX-20 and HX-21 by Toshiba in Japan at the time. This is the HX-R701 kit. It can also be used on the HX-23, HX-23F and HX-32.

Launch price for the computer: ¥79,800

This machine has been localised for France: see HX-21F


The built-in firmware is the Japanese Word Processor, that is also available on the other Japanese computers of the HX-2x serie. It's the same version as on the HX-S501 cartridge.

From BASIC, the firmware can be launched with CALL JWP or _JWP. It includes the additional BASIC instructions for Memory Disk, RS-232C and printer.

However, you need to have the HX-M200 Kanji-ROM Level 1 in one of the cartridge slots. Note that the corresponding machine in the blueMSX emulator includes this cartridge.

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-21
Toshiba HX-21 back
Toshiba HX-21 right side
Toshiba HX-21 manuals
Toshiba HX-21 label
Toshiba HX-21 box
Toshiba HX-21 inside
Toshiba HX-21 main PCB
Toshiba HX-21 main PCB bottom
Toshiba HX-21/22 RGB pinout of the video decoder PCB
Toshiba HX-21 with the RGB connector replaced by a 8-pin DIN connector


Toshiba JWP 2.0 - Intro screen
Toshiba JWP 2. 0 - Menu
Toshiba Japanese Word Processor
Toshiba JWP - Screen after ESC key
Toshiba JWP - Conversion Tools
Toshiba JWP - Load and Save
Toshiba JWP - Printer settings
Toshiba JWP - Full Book Deletion
Toshiba JWP - Idioms + Short Sentences

External links