Yamaha CX5
This page was last modified 10:17, 28 April 2021 by Mars2000you. Based on work by Rderooy 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 CX5 is the same MSX1 as the CX5F but with a cheaper keyboard and internal power supply.

Brand Yamaha
Model CX5
Year 1983-11
Region Japan
Launch price ¥59,800
RAM 32kB in slot 0
Media MSX cartridges, side slot modules
Video Texas Instruments TMS9928A
Audio PSG (YM 2149), SFG, MIDI
Chipset Yamaha YM5214
Keyboard layout QWERTY/JP50on
Extras FM synthesizer with MIDI IN/OUT connector, music keyboard connector and stereo audio out
Emulation ROM dump needed. See this thread for details


The CX5 was sold with the SFG-01 module plugged into the side slot. There is also an updated version called the SFG-05, sold separately or included with the CX5MII. From BASIC, the music firmware can be launched with CALL MUSIC or _MUSIC.



Yamaha CX5
Yamaha CX5 detail of keyboard
Yamaha CX5 left side
Yamaha CX5 back
Yamaha CX5 box
Yamaha CX5 keyboard overlay
Yamaha CX5 directional key


SFG-01 Screen

More info about the SFG modules on these pages:


The CX5 is a MSX1 with the addition of a side slot, reserved for the SFG-01 or SFG-05 module. The sound modules are 8 note polyphonic 4-op FM synthesizers by Yamaha, based on the YM2151 OPM sound chip (YM2164 in the SFG-05, which is compatible). They can be used in other MSX computers via the UCN-01 side-slot to standard MSX cartridge slot adapter.

The CX5 can be used together with the Yamaha YK-01, YK-10 and YK-20 keyboards for use with the FM synthesizer. The Toshiba HX-MU901 is also compatible.

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

To get 64kB RAM with the CX5, 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 on this machine expanded to 64kB RAM.

Slot Map

Slot 0 Slot 1 Slot 2 Slot 3
Page C000h~FFFFh RAM Cartridge
Page 8000h~BFFFh
Page 4000h~7FFFh Main-ROM
Page 0000h~3FFFh
  • By default the Module slot contains a SFG-01 from 4000-7FFF (which gets mirrored to 0000-3FFF and 8000-FFFF)