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Moonsound was the name of a sound card released for the MSX home-computer system at the Tilburg computer fair in 1995. The name Moonsound originated from the software Moonblaster that was written for people to use this hardware plug-in synthesizer.


Moonsound was a sound-card produced for the MSX home-computer system. Based on the Yamaha YMF278 OPL4 Sound chip it was capable of 18 channels of FM sound as well as 24 channels of 12 and 16 bit sample-based synthesis. It arrived after the US branch of Microsoft abandoned the MSX system, focusing on the IBM PC. A 2 MB instrument ROM containing multisampled instruments was unusual for its time.[citation needed] From the factory it came equipped with one 128 kB SRAM chip for user samples.


It was designed by electronic engineer Henrik Gilvad and produced by Sunrise Swiss on a semi-hobby basis. Two generations were made. The first was a small size PCB without a box. Later, a larger size PCB which fit into an MSX cartridge was available. The later version had room for two sample SRAM chips resulting in 1 MB of compressed user samples.


Moonblaster was software designed by Remco Schrijvers based on his time-step sequencer software for other MSX sound cards. Moonblaster came in two versions, one for FM and one for sample-based synthesis. Later on Marcel Delorme took over the software development.

Sound effects

Sound effects like chorus, delay and reverb were omitted due to cost, size and usability reasons.[citation needed] The Yamaha effect chip required its own specialised memory and effect routing was basic. All 18 FM channels and 24 channels of sample-based sound shared the same effect setting. Creative step-time sequencer programmers made pseudo effects like chorus, reverb and delay by overdubbing or using dedicated channels to repeat notes with delay and stereo panning. This was effective but quickly reduced the musical complexity possible.


Moonsound version 1.0 had 1 socket for user sample RAM. Moonsound version 1.1 and 1.2 had 2 sockets for up to 1MB SRAM. Some hackers found out how to stack additional 2 SRAM chips resulting in 2MB of SRAM.[citation needed]

Being based on OPL4, Moonsound is compatible (FM register) with OPL1, OPL2 and OPL3. The MSX-AUDIO contains a chip which is also compatible with the OPL1. So some older software can make use of the Moonsound.

The 2 MB ROM contained 330 mono samples, mostly at 22.050 kHz in 12 bits with some drums are 44.1 kHz.[citation needed]

The FM part of OPL4 chip can be configured in several ways:

  • 18 two-operator FM channels
  • 6 four-operator FM channels + 6 two-operator FM channels
  • 15 two-operator FM channels + 5 FM drums
  • 6 four-operator FM channels + 3 two-operator FM channels + 5 FM drums

Four-operator FM allows more complex sounds but reduces polyphony.

Eight waveforms are available for the FM synthesis.

The Moonsound audio power supply was isolated from its digital supply in an attempt to reduce noise. It had a separate stereo audio output and was not mixed with the internal MSX sound.


  • Moonblaster for Moonsound FM
  • Moonblaster for Moonsound Wave
  • Moonsofts Amiga MOD file Player for Moonsound
  • Mid2opl4 midi file player for Moonsound
  • Meridian SMF midi file player

Additional software tools were able to rip sound loops digitally from audio CDs inserted in a CD-ROM drive connected to any of the SCSI and ATA-IDE interfaces. This software was designed by Henrik Gilvad for MSX Club Gouda and Sunrise Swiss.

Today Moonsound is emulated in MSX emulators like blueMSX and openMSX.

See also

External links