This Yamaha computer was specialised in music and sound production. In fact it was a classic MSX 1, with a special Yamaha synthesizer built-in (SFG-01) and optional piano keyboard. It was clearly designed to be a computer for musicians.
You got 48 internal voices with a really suprising quality for that time. It was a real synthesizer (equivalent of the Yamaha DX-9 synth.), with which you could change or create your own sounds.
The CX5M was in fact the same computer as the Yamaha YS-503, but it had the SFG-01 Sound Module and MIDI interface integrated.
Malcolm Ramage adds:
The FM sound module in the CX5M was the synthesizer guts of Yamaha's FB-01 sound module and with a little utility, you could swap sounds between the CX5 and the FB-01.
Yamaha also released the C1 music laptop, this was an IBM compatable laptop, with 4 inbuilt MIDI ports for musicians on the move. The only other laptops that had anything similar were the Atari STacy and the ST Book.
This was truly an innovative piece of equipment. Not only was it a DOS (MSX-DOS) computer, but it was just like having a DX-9 synth, if you had the YK-10/20 keyboard, which I, of course owned along with it.
I composed so many songs, concertos, hymns, etc on it. I had quite a few of the ROM cartridges, the disk drive, the SERIAL printer, the YK-20 keyboard and the FB-01 sound module (a DX-7 in a box).
You could edit all the sounds-EASILY! You could write and print music. You could write text documents. This thing was not only fast, but easy to program in BASIC. I wish I still had it. Someone should come up with something similar today....