Yamaha CX7M/128
This page was last modified 15:14, 16 December 2021 by Mars2000you. Based on work by Rderooy and Gdx.




The Yamaha 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 MSX computers and can be used as such.

The CX7M/128 was aimed at the Japanese market and features a Japanese keyboard. It is a full MSX2 while the corresponding Yamaha CX5MII machines for the international market are MSX1 with the MSX2 VDP.

The CX7M/128 has been localised

Brand Yamaha
Model CX7M/128
Year 1985
Region Japan
Launch price ¥128,000
RAM 128kB (in slot 3-2)
VRAM 128kB
Media MSX cartridges, side slot modules
Video Yamaha V9938
Audio PSG (YM2149 integrated in MSX-Engine S3527), SFG, MIDI
Chipset Yamaha S3527
Keyboard layout QWERTY/JP50on
Extras Reset button, 60 pin module port, mini cartridge port, FM module SFG-05, YRM-502 FM Voicing Program II
Emulation Emulated, but based on CX7/128 machine. Needs validation. See this thread for details


This machine was sold with a FM module SFG-05 plugged into side slot. From BASIC, the synthesizer can be launched with CALL MUSIC or _MUSIC.

It has also a mini cartridge YRM-502 FM Voicing Program II. From BASIC, this sound editor can be started with CALL FMV or _FMV. Contrary to the first version of this software, only available as cartridge (YRM-102), this second version has support for loading from/saving to disk.

When you are in the sound editor, you can go to the synthesizer by entering MU. To go back to the FM Voicing Program, you need to press ESC in the synthesizer firmware.



Yamaha CX7M/128
Yamaha CX7M/128 back
Yamaha CX7M/128 bottom
Yamaha CX7M/128 mini cartridge slot
Yamaha CX7M/128 left side
Yamaha CX7M/128 right side
Yamaha CX7M/128 label
Yamaha CX7M/128 manuals
Yamaha CX7M/128 inside
Yamaha CX7M/128 mainboard
Yamaha CX7/128 - CX7M/128 manuals


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


YRM-502 Command menu
YRM-502 Edit mode (F1)
YRM-502 Directory (DI)
YRM-502 Edit key list (F5)
YRM-502 Command key list (F5)
YRM-502 Load/Save menu (TR)
YRM-502 Common key list (F5)


The CX7M/128 is a MSX2 with a Z80A from Sharp (LH0080A) and an MSX-Engine S3527 from Yamaha.

This model can be easily upgraded internally because RAM and VRAM are on separate boards with a connector, you just need to change the corresponding board.

The mini slot allows to add software.

Slot Map

Slot 0 Slot 1 Slot 2 Slot 3-0 Slot 3-1 Slot 3-2 Slot 3-3
Page C000h~FFFFh Cartridge
Slot 1
Slot 2

Page 8000h~BFFFh
Page 4000h~7FFFh Main-ROM
Page 0000h~3FFFh Sub-ROM
  • By default the Mini-Cartridge slot contains a FM Voicing Program II cartridge (YRM-502) from 4000-7FFF
  • By default the Module Slot contains a SFG-05 module from 0000-7FFF