The Yamaha CX5M Music Computer

By 1983 the consumer was spoiled for choice when it came to purchasing a home micro-computer.

Apple, Atari and Commodore all had their own systems in the mix, along with those from smaller companies. With so many incompatible systems on the market it was tricky for the lay person to choose a system. Do you buy an Apple knowing you cannot use software made for the Atari and Commodore computers? Do you buy a Spectrum knowing you cannot use anything developed on a BBC Micro or Tandy computer?

Enter Kazuhiko Nishi, director of the ASCII Corporation and friend to Bill Gates. Nishi-san had already assisted in the development of Japan’s first attempt at standardising the computer market, the NEC PC-8001. Using a version of Microsoft BASIC, this computer helped establish NEC as the leaders in home computing. This was a title they would hold until the late 90s, when Japan decided to adopt the Western PC standard.

However, Nishi-san was not one to rest on his laurels, and four years after his success with NEC it was time to develop something new. Though the PC-8001 was designed to be a standard, there were still computers being released from other companies that were not compatible with NEC’s micro. This time Nishi-san did not place all of his bets with a single company, but he instead sought to get different manufacturers on board while developing what would be known as the MSX. Once again, his friend Bill Gates was on board to help develop this new standard of computer.

Variations of the MSX were released by Sony, Philips, Casio and more. Though the core of these computers remains the same, manufacturers were welcome to add to the hardware as long as it remained compatible with the MSX standard. One such developer of MSX hardware was Yamaha, a company best known for its musical hardware.

The Yamaha CX5M, released in 1984, was marketed as a “musical computer”. As well as being able to expand the computer with a printer, tape drive and other common devices, the CX5M was able to interface directly with a Yamaha musical Keyboard. With the special interface installed on the left side of the computer, you could connect to a Yamaha YK-01, YK-10 or YK-20 keyboard.

This interface, known as the SFG provided audio abilities above those of a standard MSX. The CX5M and later Yamaha computers, such as the CX11 came with an SFG-01 already installed. This device allowed the CX5M to play up to eight sounds simultaneously. Enhanced features were enabled when coupled with the YRM-501 FM Music Computer. Though designed for the CX5M, the box to the SFG module suggests it can be connected to other MSX computers through the use of the UCN-01 adapter.

The SFG module contains a ROM which allows quick access to the musical application required to use the keyboard. One simply needs to type “call music” from MSX BASIC to bring up the interface. From here the keyboard can be set to emulate various musical instruments, including a trumpet, guitar and piano. Backing tracks can be selected and the speed can be adjusted, as can the tempo and bass.

The two SFG modules that were released contain different on board chipsets. The SFG-01 features a YM2151 OPM sound chip and a YM2148 MIDI UART. It contains a 16k ROM which is unable to receive MIDI input, though it can output MIDI data to the Yamaha DX7, or similar device. The SFG-05 boasts an improved YM2164 OPP sound chip to go with its YM2148 MIDI UART. Unlike its predecessor, it features a 32k ROM which supports MIDI input. This means it is not restricted to using only a Yamaha YK keyboard.

Various cartridges were developed by Yamaha that took advantage of the SFG module. These include the aforementioned YRM-501 FM Music Composer, which also enabled you to compose your own music, and the YRM-102 FM Voicing Program which allowed you to create your own musical instruments. These instruments could then be used with the keyboard to create customs arrangements.

Unlike many MSX computers, which only saw release in Japan, the CX5M was released in the UK, US and Australia. Those who have documented the history of the computer claim that the CX5M was released in music stores, as opposed to computer hardware outlets such as Dick Smith or Tandy Electronics. These music stores would have the keyboard available for sale, as well as the computer itself. It is worth noting that the Yamaha YK keyboards are useless without an MSX CX computer with SFG interface.

As well as having on board musical capabilities, the Yamaha CX5M was a standard MSX 1 computer containing 32k of RAM and 16k of VRAM. The computer received a couple of hardware revisions that saw various levels of MIDI support. Standard MSX 1 games were compatible with the system, so you could play some Bomberman or Gradius between music sessions.

One year after the the CX5M debuted, Yamaha released the CX11. Containing similar specs, this MSX variant contained two expansion ports on top of the computer (the CX5M had one on top and one on the back), and the ability to easily upgrade it to an MSX 2. It came with the SFG-01 FM synthesiser which like its predecessor could be replaced with the SFG-05 model.

Yamaha released the URM-01, which was a 32k expansion released around the same time as the CX11. Unfortunately the RAM is configured in a way that can cause the computer to become unstable. For the modern collector, many third party RAM expansions are available, and the MSX community suggests using one of those over the old Yamaha model.

The user is also able to upgrade the RAM internally, which is recommended should they wish to upgrade the computer to MSX 2 specifications. The Yamaha CX11 comes with most of the internal components that can be found in later models. All that is required is to upgrade the RAM, VRAM and ROM and you will have a fully functioning MSX 2.

Shortly after the release of the CX11, Yamaha released the final computer in the line. This MSX 2 standard computer was known as the CX7. At the time it was seen as one of the more desirable computers, owing to its 128k RAM, at a time when most came with 64k on board. Yamaha released their YIS line of MSX computers concurrently with the CX7. These new systems also had the extra slot for the SFG FM module. Unfortunately these computers also signalled the end of Yamaha’s involvement with the MSX standard.

Though the MSX line extended to the MSX2+ and the MSX Turbo R, many collectors still prefer these older machines in their collection. If you are in the market for an MSX you will find them on Japan Yahoo Auctions for a reasonable price. If you have yet to delve into the world of MSX computing then open up a proxy account and place a bid.

Whether you be musically inclined or just a gamer looking for a new system, you will be pleasantly surprised.