Category:Toshiba HX-20
This page was last modified 00:58, 18 January 2021 by Mars2000you. Based on work by Rderooy and Manuel and others.



The HX-20 is the first computer released by Toshiba in his second serie of MSX computers. Contrary to its follower, the HX-21, this machine is without a RGB output connector. The following models exist:

Product Region Keyboard Video and audio out Other
HX-20 JP QWERTY/JIS RF, composite video and stereo audio Optional RS-232C module
HX-20AR AR QWERTY with accent key RF, composite video and mono audio
HX-20E ES QWERTY with accent key (no ñ!) RF, composite video and mono audio
HX-20I IT QWERTY with accent key RF, composite video and mono audio

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).

Brand Toshiba
Type HX-20 / HX-20AR / HX-20E / HX-20I
Year 1984-10-16 in Japan - 1985 in Spain - 1986 in Argentina
Region Argentina, Italy, Japan, Spain
Original price ¥69,800
RAM 64kB split between slots 0 and 3-0
Media MSX cartridges
Video TMS9128 (HX-20AR) or Toshiba T6950 (other models)
Audio PSG (AY-3-8910A)
Chipset Toshiba TCX-1010 or Toshiba TCX-1012
Keyboard layout see table above
Extras firmware (Japanese Word Processor - Kanji-Kun v.2.0 or English Word Processor), MemoryDisk BASIC, (only Japanese version) Printer BASIC and stereo PSG sound, (only Japanese version and optional) RS-232C interface + switch + RS-232C BASIC
Emulation HX-20E dumped and emulated. ROM dump needed for the other versions. See this thread for details


Check also the pages about the different models!

Toshiba HX-20
Toshiba HX-20E
Toshiba HX-20I
Toshiba HX-20 back
Toshiba HX-20I back
Toshiba HX-20I right side
Toshiba HX-20AR
Toshiba HX-20AR inside
Toshiba HX-20E PCB


The HX-20 is a MSX1 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 used VDP is most versions of this computer is the Toshiba T6950, which does not support some undocumented features of the Texas Instruments TMS9918, TMS9928 and TMS9929 VDP's.

The 64kB RAM is split between 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
32kB RAM
Slot 1
Slot 2
Page 8000h~BFFFh Firmware
Page 4000h~7FFFh Main-ROM Lower
32kB RAM
Page 0000h~3FFFh


External links

Pages in category "Toshiba HX-20"

The following 4 pages are in this category, out of 4 total.