What is it?

Excited to embark on a new electronics project: delving into the RBSC SFG05/01 cartridge for MSX computers!
This work was originally created by the RBSC group, all files are available on their GitHub repository here RBSC/SFG_Cartridge: Yamaha SFG 05/01 OPM/OPP cartridge (github.com)
But what exactly is this SFG05/01 cartridge all about? Let’s rewind to the mid-80s, the heyday of MSX computers, and Yamaha introduces the CX5M – not just your average MSX1 computer, but a music lover’s dream, equipped with a music expansion module featuring Yamaha’s iconic chips straight from their top-of-the-line synths and arcade machines.

Why did you make it?

The CX5M came in three flavors. The original version rocked the FM module SFG-01 with the YM2151 OPM chip. But here’s the catch – it couldn’t sync up with external MIDI devices and needed its own special keyboard. Then after some time Yamaha released the CX5M II (or CX7M/128 in Japan), boasting the upgraded FM system, SFG-05, powered by the YM2164 OPP chip. That beauty could harmonize with any MIDI keyboard, unlocking a whole new world of musical possibilities.

The music module was the heart of the computer music soul. Initially the SFG01 module, based on the YM2151 (OPM) and later the SFG05 module, based on the YM2164 chip (OPP).
Originally bundled with Yamaha CX5M MSX (and other Yamaha computers), these SFG05 and SFG01 modules were renowned for their stellar sound quality. But here’s the kicker – they only played nice with Yamaha computers sporting the right slots, leaving other MSX users out in the cold.

But how to have those features with the rest of the MSX compatible computers? The Russion RBSC group heard the pleas of MSX enthusiasts worldwide and came up with a brilliant solution – transforming those SFG05/01 modules into a standard MSX cartridge. Voila! Suddenly, everyone could experience the magic of Yamaha’s sound, regardless of their MSX model.

What makes it special?

The cartridge is based on two printed circuit boards. The main board implements the basic logic, has the flash memory with the basic software for both the SFG01 and SFG05 modules, and hosts the Yamaha chips required. The extension board implements the appropriate connectors to link MIDI devices as well as speakers.
The SFG05 software/ROM has some changes as only the YM2151 chip is present. Originally the SFG05 module had a ROM to use the YM2164 OPP chip, but this cartridge leverage only the OPM version.