Yamaha YIS-805
This page was last modified 18:54, 11 April 2021 by Mars2000you. Based on work by Rderooy and Gdx and others.




The Yamaha YIS-805 comes with a separate keyboard and in 2 versions:

  • The /128 version has only 128kB RAM and 1 disk drive by default, but there's a location planned for the addition of a second disk drive
  • The /256 version has 256kB RAM, 2 disk drives and a RS-232C interface (compatible, via SCA-01 adapter, with the NTT Captain network)

Both versions have an expansion bus at the back, reserved for a digitizer, also known as 'video enhancer'.

It's the last computer released by Yamaha for the MSX system and the only one with a built-in floppy drive. It has still a special slot for specific Yamaha modules.

The Yamaha YIS-805 was advertised to be used with the following software and extensions:

  • FM Sound Synthesizer Unit Ⅱ SFG-05 ¥ 29,800
  • FM Voicing Program II YRM-55 ¥ 9,800
  • Paragraph Transfer cartridge YRK-50 ¥ 24,800
  • MSX Captain adapter unit SCA-01 ¥ 40,000
  • Captain modem MD-01 ¥ 98,000
  • EFD-10 Second disk drive for the YIS-805/128 ¥ 40,000

The YIS-805/128 has been localised for the Russian market - see YIS-805/128R2 - without the expansion bus slot.

The YIS-805/256 has been localised for the Arabic countries - see Sakhr AX-500 - without the expansion bus slot and the RS-232C interface.

Brand Yamaha
Type YIS-805/128 or YIS-805/256
Year 1986-06-21
Region Japan
Original price ¥148,000 for the YIS-805/128
¥198,000 for the YIS-805/256
RAM 128kB or 256kB (? in slot 3-2) + 2kB SRAM
VRAM 128kB
Media MSX cartridges, 2DD floppy disks
Video Yamaha V9938
Audio PSG (YM2149 integrated in MSX-Engine S1985)
Chipset Yamaha S1985
Keyboard layout QWERTY/JIS
Extras 1 or 2 720kB 3,5" floppy disk drives, THE PAINTER (graphic tool), Kanji Word Processor Unit SKW-05 with Kanji-ROM Level 1, 'Beginner's Lesson' module, 2DD disk with YIS-805 Set Up Program and MSX-DOS 1, (only /256 version) RS-232C interface + RS-232C BASIC
Emulation /128 version: several ROMs dumped but machine not yet emulated. /256 version: ROM dumps required. Both versions: SKW-05 ROMs, module and system disk dumps needed. See this thread for details


This machine comes with

  • the firmware THE PAINTER, a graphic utility in screen 5 (64kB ROM) that can be launched with CALL PAINT or _PAINT, but you can also boot the computer while pressing the SPACE key to directly start this utility.
  • the firmware Kanji Word Processor Unit SKW-05 that includes
    • a 48kB ROM with the application that can be launched with CALL JWP or _JWP
    • a 32kB ROM with a Kanji Dictionary
    • a 2kB SRAM
    • a non-standard 128kB Kanji-ROM (JIS1) with 3979 characters.


This machine was provided with

  • the software 'Beginner's Lesson' on a module inserted in the special slot
  • a floppy disk with YIS-805 Set Up Program and MSX-DOS 1



Yamaha YIS-805/128
Yamaha YIS-805 underside
Yamaha YIS-805 right side
Yamaha YIS-805/256 front
Yamaha YIS-805 keyboard
Yamaha YIS-805/256 front
Yamaha 'Beginner's Lesson' module
Yamaha YIS-805 manuals + module
Yamaha YIS-805/128 back
Yamaha YIS-805/256 back


The Painter
The Painter


The YIS-805 is a MSX2 with a Z80A from Sharp (LH0080A) and an MSX-Engine S1985 from Yamaha. This computer is available in two models. One with 128kB RAM and one with 256kB RAM.

The /128 version can be easily upgraded internally to 256kB RAM.

Floppy Disk Controller chip is the 8876.

Slot Map

Help needed
The below slot-map is an assumption, it needs to be checked on a real machine. It is also uncomplete, as the Kanji Word Processor Unit needs to be added.
Slot Slot
0-0 0‑1 0-2 0-3 Slot 1 Slot 2 3-0 3-1 3-2 3-3
Page C000h~FFFFh Expansion
Slot 1
Slot 2
Page 8000h~BFFFh
Page 4000h~7FFFh Main-ROM RS-232C
Disk ROM
Page 0000h~3FFFh Sub-ROM
  • By default the Module Slot contains the Beginner's Lesson module
  • The RS-232C ROM is a 8KB ROM - 4000h-5FFFh - it is not present on the YIS-805/128 model
  • In the Russian version of YIS805/128, slot 0 is not expanded. The RS-232C ROM is not present, but in the side slot there is the special "network" module to communicate with students' computers that have similar modules - see YIS-805/128R2


  • RGB output
  • RF output
  • Analog sound & Composite video
  • Keyboard connector
  • Data Recorder connector
  • Centronics compatible Parallel port for a printer
  • 2 general connectors (Joysticks, Mouse, Paddle controlers, etc)
  • 2 cartridge slots
  • 1 expansion bus slot
  • 1 module slot (on right side, 60 pin connector)
  • RS-232C connector (only /256 version)
  • Power plug for main power supply (JIS C 8303 class, AC 100V +/-10% 50/60Hz)
  • 2 power sockets for monitor and another device (AC 100V)