Yamaha YIS-503II
This page was last modified 22:45, 13 February 2018 by Rderooy. Based on work by Mars2000you and Gdx and others.



The Yamaha CX5, CX5F, CX5M, CX5MII and CX5MII/128 computers were specifically targeted at music and sound production, and as such were regarded by many as non-standard MSX machines. However, they are in fact standard MSX1 computers and can be used as such.

The YIS-503II was aimed at the Japanese market and features a Japanese keyboard. It is same as the CX11 but has more RAM and was sold without any module.

Official price: ¥59,800

This model has been also localised and modified to be sold in Arabic countries - see Sakhr AX-200 - or used in schools of Soviet Union - see YIS-503IIR.

Brand Yamaha
Type YIS-503II
Year 1985 (Japan)
RAM 64kB in slot 3-2
Media MSX cartridges, side slot modules
Video Yamaha V9938 (MSX2 VDP!)
Audio PSG (YM2149 integrated in MSX-Engine S3527)
Chipset Yamaha S3527
Extras Internal RAM / VRAM expandable, 60 pins connector, mini slot


Yamaha YIS-503II
Yamaha YIS-503II left side
Yamaha YIS-503II under side (with empty module slot)
Yamaha YIS-503II with box
Yamaha YIS-503II back


The YIS-503II is a MSX1 with a Z80A from Sharp (LH0080A), a V9938 and an MSX-Engine S3527 from Yamaha.

This computer supports all Yamaha modules. Itl can be easily upgraded internally because RAM and VRAM are each on separate boards with a connector, you just need to change the corresponding board.

The mini slot allows to add software as on the Yamaha CX5MII.

Slot Map

Slot 0 Slot 1 Slot 2 Slot 3-0 Slot 3-1 Slot 3-2 Slot 3-3
Bank C000h~FFFFh
Slot 1

Slot 2



Bank 8000h~BFFFh
Bank 4000h~7FFFh Main-ROM Sub-ROM
Bank 0000h~3FFFh Main-ROM


  • RGB output
  • RF output
  • Analog sound & Composite video
  • Tape recorder connector
  • Centronics compatible Parallel port for a printer
  • 2 general connectors (joysticks, mouse, paddle controllers, ...)
  • 2 cartridge slots
  • 1 module slot (left side, 60 pin connector)
  • 1 Mini Cartridge slot

See also