Description

Cartridge

The Toshiba HX-MU900 is the almost MSX-AUDIO with the most flanged functions. It lacks built-in Sample RAM, MSX-AUDIO BASIC/BIOS and a sound input to be complete.

The product name is "FM-Synthesizer Unit". It was made in Japan, but only sold in Europe.

Some exemplars have a switch at the top of the cartridge. It is a low-pass filter for the PCM output. The FM synth is not affected by this filter.

Brand	Toshiba
Model	HX-MU900
Year	1985
Region	Europe
Launch price	IT: L. 340,000 NL: ƒ399 (incl. HX-MU901)
Package content
Emulation

Firmware

This cartridge has a built-in music program, called 'MSX Music-System' that boots up automatically, but can be skipped by holding the ESC key. This firmware is also available on the Panasonic FS-CA1 cartridge, but slightly modified.

The menu of this specific utility gives access to three FM musics and a music editor. You can notice that the menu screen creates some confusion with MSX-MUSIC.

From MSX-BASIC, it can be launched by entering CALL SYN or _SYN

Notes:

On the Philips NMS 8220 pressing ESC on startup to skip the integrated Designer firmware will also prevent the MSX Music-System software from starting at the same time. In this case, start it from MSX-BASIC with CALL SYN.
Upgraded versions made by the MSX scene inverse the procedure as you need then to press the ESC key while booting to launch the firmware.