Yamaha CX5M

Name: Yamaha CX5M
Brand: Yamaha

A Z-80 MSX machine that Yamaha sold as a music computer. A small, stubborn cult of owners still treats it as one.

Overview

The CX5M makes sense once you know what Yamaha was after. It was not a synthesizer with a computer bolted on, and it was not a home computer with a token music mode. Yamaha positioned it as a dedicated music computer. The company's own advertising at the time called it "the only computer dedicated to compose, record and play music," and the pitch was composition, recording, and playback in one integrated system instead of a pile of separate boxes.

Underneath is a Z-80 based, MSX-standard compatible computer, according to Polyphony (April 1985, p.27), which also reported the price at $469. The MSX part matters here. MSX was a standardized home-computer architecture, so the CX5M sat inside an ecosystem instead of standing alone. Studio Sound (June 1984, p.50) noted that more software was available for MSX micros than for any other platform at that moment, and that other MSX machines, the Sony Hit Bit HB-55 and the Sanyo Wavy 10 MPC-10, were already on the Japanese market. The CX5M's bet was that a standardized platform with a deep software library would beat a proprietary music box.

The FM synthesis hardware and the software built around it are what made it a music computer. The FM Music Composer software let users enter key, time signature, notes, rests, tempo, dynamics commands, voices, and other music parameters directly onto a score. It then played the result back through the internal FM synthesizer or out to MIDI-equipped synthesizers and drum machines. DB Magazine (May 1986, p.58) listed it at $50. The same issue documented the FM Voicing Program, which allowed editing of the CX5M's standard 46 voices or the creation of entirely new ones using the built-in FM digital synthesizer, also at $50. The DX-7 Programming Software let CX5M users create and edit voices for the DX7 FM synthesizer by displaying the DX7's voice parameters on the CX5M screen, storing up to 46 voices - again $50.

The expansion side is where the CX5M gets interesting for collectors. Yamaha's own promotional material describes the SFG05 module as one of the new hardware add-ons. It is an FM tone generator with 46 of its own preset voices, an 1800-note sequencer, and room for 48 user-programmed voices. The same material lists the FD03 Micro Floppy Disk Drive as a storage expansion, and says a printer and a mouse rounded out the setup: the PN101 dot impact printer and the MU01 Mouse. The MIDI Recorder program, per that same promotional copy, offered four banks each containing four recording tracks. Users could compose and arrange in step-time or real time from any MIDI keyboard, then synchronize playback through DX synthesizers or FM tone generators such as the TX7. The RX Editor program added programming for the RX11, RX15, or RX21 digital rhythm machines. Yamaha's advertising also pointed out that "the basic CX5M computer doesn't go for any more than it did at its debut," which reads as reassurance to early adopters as much as a sales pitch.

There is a detail buried in the DX7 voicing documentation that speaks volumes about how these systems actually behaved in use. When transmitting a single voice, both voice parameters and function parameters are sent; when transmitting all 32 internal voices, only voice parameters go out. And when using the DX7 with the CX5M and the YRM-103 or TRM-304 DX7 Voicing Programs, the MIDI System Information function had to be manually set to ON — the voicing programs would no longer set it automatically. That kind of manual housekeeping is the reality of 1980s computer-music integration, and it is exactly the sort of thing that separates the collectors who still use these machines from the ones who just display them.

The second-generation machine, the CX5M II, appears in contemporary dealer listings. A Toronto MIDI specialist advertised software support for "CX5M II" alongside the original, which suggests the line continued and that Canadian buyers at least had a specialist channel for it. Beyond that, the documentary trail for the II is thin in the sources at hand.

British music press classifieds from the mid-1980s show these machines changing hands regularly. One listing reads "Yamaha CX5M large keyboard, with Voicing and Composer ROMs, excellent condition" at £299, and multiple machines with three ROMs, boxed manuals, and mint condition went for similar money. The same columns show user-made sound libraries: "144 CX5M voices on good quality tape" for £5, "144 CX5M sounds on cassette, + data sheets" for £10, and at least three separate sellers offering 144-sound collections by mail order. One classified even offered "YAMAHA CX5M 48 drum and synth sounds on data cassette" for £5 including postage. The machine also turns up in wanted ads: "CASH PAID for MIDI synths and accessories, CX5M computers."

The practical caveats are the usual ones for a machine of this vintage and architecture. The CX5M is an MSX-standard computer first, so its usefulness today depends heavily on the survival of its software media, cartridges and data cassettes, and on the condition of the FM hardware inside. The promotional material's emphasis on the SFG05 module, the FD03 floppy drive, and the various ROM programs suggests a complete, working system is a collection of pieces rather than a single unit, and buyers should expect to hunt for those pieces separately. The period classifieds also tie the CX5M's value to its software: a machine with the Voicing and Composer ROMs commanded real money, and one without them was a paperweight with a keyboard.

What the CX5M represents, more than any single spec, is Yamaha's bet that a standardized computer platform could be the center of a music production system. It was not the most powerful FM synthesizer Yamaha made, and it was not the most capable computer of its era, but it was the one Yamaha built specifically to sit between the two — and the users who bought it, traded patches for it, and programmed DX7s through it clearly got the point.