Yamaha cx5m MSX

Last updated on: June 1 1999

This is a text about the Yamaha cx5m MSX computer which was once posted to comp.sys.msx by Eirik Lie.

The author of this text can be reached at

Eirik Lie
PB 6820 Elgeseter
N-7002 Trondheim

E-mail: eirikli@notam.uio.no

The Yamaha CX5M was made around 1985 and was based on the MSX standard, which was a great flop. It had a Z80 CPU and ran, apart from ROM BASIC, an operating system equivalent to MS-DOS 1.0, if you can imagine. However, it also had a built-in 4-operator FM synth (as opposed to the DX7's 6 operators), soundwise equivalent (and patch- compatible, I think) to the DX21, DX100, and FB-01. The original CX5M could only be played with a proprietary non-velocity sensitive Yamaha keyboard, and not via MIDI. It could be upgraded, however. If you take a look under your CX5M you will see the bolted-on synthesizer unit. If you can read 'Yamaha FM Sound Synthesizer Unit II' and 'Model SFG-05', you have the upgraded version. There also was a later model called the CX5M II/128. These two latter versions were velocity-sensitive playable via MIDI. You cannot use an RGB monitor with the CX5M, you only have an RF output to go into the antenna socket on your TV, and a 'composite video' output, also found on many TV sets and old PC monitors. Software for the CX5M came in the form of plug-in cartridges. If you have the original CX5M, the only cartridges of any use would be: 1. The YRM-303 MIDI Macro & Monitor, showing MIDI messages on screen, very handy for MIDI system troubleshooting, and: 2. A DX7 editing program of which I can't remember the name, making it possible to edit DX7 sounds on screen instead of the DX7's LCD display. If you have one of the upgraded versions, however, you will be able to use it as an external MIDI sound device. You then also will need the 'YRM-502 FM Voicing Program II' cartridge to edit the internal sounds. The CX5M is 8-voice, 4-channel multitimbral without dynamic voice allocation. Storage of sounds is on cassette tape. Any tape recorder can be used, but you need a special DIN-to-minijack cable, originally included with the CX5M. There was also an external disk drive available, but it was terribly expensive and very difficult to find. When you boot the CX5M, it defaults to the ROM BASIC, with no access to the synthesizer unit. You have to type 'call music' to get access to the synth, 'call fmv' to access the FM Voicing program, etc. I still use my CX5M in my MIDI rig at home, both as a sound module, and as a patch and sequencer library for my ESQ1 synth, a program I wrote myself. (And I still play "Chuckie Egg" regularly!) I hope this information has been of some help for you. Feel free to email me if you have more questions.