Yamaha YIS-503
This page was last modified 14:34, 18 December 2017 by Rderooy. Based on work by Mars2000you and Gdx and others.



The YIS-503 is same as the CX5F but sold without any module. The color is different.

It was aimed at the Japanese market and features a Japanese keyboard. The power supply is internal.

Official price: ¥64,800

It was also offered in packages with other Yamaha hardware:

  • YIS-503G (Graphic System) = YIS-503 + ZGA-01 (Graphics Card Set = CR-01 + UGA-02) + VC-01 (video cable)
  • YIS-503M (Music System) = YIS-503 + YK-10 (Music Keyboard) + SFG-01 (musical module) + VC-01 (video cable) - eventually, it was possible to buy later the more advanced SFG-05 module
  • YIS-503W (Word Processing System) = YIS-503 + SKW-01 (Kanji Word Processor Unit) + PN-01 (thermal printer) + CB-01 (printer cable) + VC-01 (video cable)

The YIS-503 has been adapted for the French and Belgian markets - see Yamaha YIS-503F - and for the Arabic countries - see Sakhr AX-100.

Brand Yamaha
Type YIS-503
Year 1984
RAM 32kB in slot 0
Media MSX cartridges, side slot modules
Video Texas Instruments TMS9928A
Audio PSG (YM2149), (Music System package) SFG
Chipset Yamaha YM5214
Extras see the Graphic System, Music System and Word Processing System packages



Yamaha YIS-503 box and content
Yamaha YIS-503 box
Yamaha YIS-503 label
Yamaha YIS-503 underside
Yamaha YIS-503box and computer
Yamaha YIS-503 PCB

Firmware of SFG modules

SFG-01 Screen
SFG-05 Polyphonic mode (F2)
SFG-05 Monophonic mode (F1)
SFG-05 Voice menu (F3)
SFG-05 Load/Save menu (F4)


The YIS-503 supports all Yamaha modules.

To use the extension bus as a second cartridge slot, you need the Yamaha Single Cartridge Adapter CA-01.

To get 64kB RAM with the YIS-503, you can insert the URM-01 cartridge in slot 1 or 2 or the SRE-01 module in side slot 3. It means that the 64kB RAM is split between two slots, 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. As such it is recommended to use a 64kB expansion, or a MSX1 compatible MemoryMapper that can self-initialise.


  • Monitor output
  • Tape recorder connector
  • Centronics compatible Parallel port for a printer
  • 2 general connectors (joysticks, mouse, paddle controllers, ...)
  • 1 cartridge slot
  • 1 module slot (left side, 60 pin connector)
  • 1 extension bus slot (back side, 2nd cartridge slot via CA-01 adapter)

See also