Bit^2 Mu-pack
This page was last modified 12:31, 7 December 2021 by Mars2000you. Based on work by Gdx and Grauw and others.


The Bit² μ·PACK BM-117 (Mu-Pack) is an external version of the built-in MSX-MIDI interface of the Panasonic FS-A1GT and is compatible with it. It is intended to upgrade the older Panasonic FS-A1ST to the latest specification of the MSX Turbo R. It was only sold in Japan and a few were imported to Europe. It’s very rare nowadays.

The cartridge contains:

  • MIDI-IN and MIDI-OUT connectors
  • 16kB MIDI-ROM with built-in MSX-MIDI BASIC. You need to enter CALL MUSIC to activate MSX-MIDI, then you can use PLAY#1.
  • 256kB memory mapper in subslot 1 - This memory extension is intended to use μ·SIOS (Mu-SIOS) on the FS-A1ST because this software requires 512kB.

Note that although the µ-Pack extends the ST’s memory by 256kB to a total of 512kB, on the MSX Turbo R external memory is slower than the internal memory. Additionally, not all software can make use of multiple memory mappers. To have the same memory capabilities as the GT, the internal memory of the ST can be extended to 512kB instead.

When the μ·PACK cartridge is used on the FS-A1GT its MIDI-OUT connector is usable as extra.

Note: This cartridge doesn't work in a cartridge slot expander.

Software with MSX-MIDI support:

Although the μ.Pack was initially designed for upgrading the FS-A1ST to the FS-A1GT, it's confirmed this extension also works on MSX2/2+ as shown in the video over here . However, only the memory mapper and MIDI interface work on MSX2/2+. CALL MUSIC gives "Illegal function call" error message on original ROM as it checks for the MSX Turbo R.


Bit² μ·PACK front
Bit² μ·PACK box
Bit² μ·PACK contents box