Toshiba HX-23F
This page was last modified 15:52, 18 August 2019 by Mars2000you. Based on work by Rderooy and Gdx and others.




The HX-23F is an improved version of the HX-23 computer as it comes with 128kB VRAM instead of only 64kB. As on its brother, the RS-232C interface with switch is optional. As for many machines with the "Pasopia IQ" label, the PSG sound output is stereo, with a switch at the back. This computer was aimed at the Japanese market.

Brand Toshiba
Type HX-23F
Year 1985
Region Japan
Original price ¥108,000
RAM 64kB split between slots 0 and 3-0
VRAM 128kB
Media MSX cartridges
Video Yamaha V9938
Audio PSG (AY-3-8910A)
Chipset Toshiba TCX-1012
Extras firmware (Japanese Word Processor), stereo PSG sound, Printer BASIC, (optional) RS-232C interface + switch + RS-232C BASIC


The built-in firmware is version 2.5 of the Japanese Word Processor, that is also available on the other Japanese computers of the HX-2x serie. From BASIC, the firmware can be launched with CALL JWP or _JWP. It includes the additionnal BASIC commands for 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



Toshiba HX-23F
Toshiba HX-23F back
Toshiba HX-23F left
Toshiba HX-23F right
Toshiba HX-23F battery
Toshiba HX-23F box
Toshiba HX-23 / HX-23F manuals


Toshiba Japanese Word Processor
Toshiba Japanese Word Processor
Toshiba Japanese Word Processor
Toshiba Japanese Word Processor
Toshiba Japanese Word Processor


The HX-23F is a MSX2 with 2 cartridge slots (one at the top, one at the back) and a a Z80A from Sharp (LH-0080A). The 2 joystick ports are located on the right side of the computer, as well as the data recorder connector.

The 64kB RAM is split in half between the slots 0 and 3-0, a configuration that can cause poorly written software to crash. Also, with this layout, the POKE-1,(15-PEEK(-1)\16)*17 trick to workaround buggy software that does not handle subslots properly will not work on this machine.

Slot Map

Slot 0 Slot 1 Slot 2 Slot 3-0 Slot 3-1 Slot 3-2 Slot 3-3
Page C000h~FFFFh Upper
32k RAM
Slot 1
Slot 2
Page 8000h~BFFFh JWP 2 JWP 1
Page 4000h~7FFFh Main-ROM Lower
32k RAM
Page 0000h~3FFFh Sub-ROM