BBC Micro hardware emulation with the MiST FPGA

Feb 5, 2018  

MiST BBC Menu

You can find more about the MiST in the following link: MiST FPGA

For information from the developer of the MiST please visit their website at harbaum.org

To get the MiST configured to work with BBC, it’s slightly different to other cores, as it has slightly different requirements for the SD card.

Basically, the MiST’s SD card is normally installed with the following:

  • The FPGA image core.rbf - this is used to program the FGPA chip to operate in the same way as the original hardware.
  • The software level firmware / ROMs. This isn’t required for the BBC as it’s built in to the core (os1.2, basic2 and SuperMMC).
  • Games! See the section on beeb.mmb below.

You can find files and links mentioned here on the Github page here: BBC Micro Binaries and instructions on Github

core.rbf

This is the binary that gives instructions to the MiST that configure the FPGA chip to operate as closely to the original cpu, graphics and sound chips from the hardware being emulated.

As this is programmed to the FGPA by the MiST, then the internal firmware of the MiST also needs to be a similar version. Basically try to ensure that the internal firmware and the FPGA core are the latest versions, although if the core.rbf hasn’t been updated for quite a while, and you’re experiencing problems, then an older MiST firmware may be needed to be installed.

Sometimes ROMs are also required to be included on the SD card (i.e. Kickstart for Amiga), and because of legal / licensing reasons, you will often need to find these yourself.

The good news is that for the BBC Micro, no additional files are required.

beeb.mmb

This one I would highly recommend. The core file above is designed to work with beeb.mmb which is a file format for containing several roms and I believe that it can hold up to 512 or so game images. In addition to that, you can load up a menu to show all of the games with the command *MENU (from the BASIC command prompt), or by selecting Auto boot from the MiST’s on-screen display.

It might not be so easy to find the beeb.mmb image as the links on the github page now appear to not be working. However, if you’re interested, perhaps someone at stardot.org.uk could help.

IMPORTANT To use beeb.mmb you must format the SD card as FAT16 and copy thebeeb.mmb file to the card first

There’s an interesting discussion on this file, and related hardware mods for the BBC Microcomputer over on stardot.org.uk.

How well does it work?

Frankly, the experience I’ve had with MiST and the BBC Micro core has been fantastic, and especially since someone thankfully fixed horrible audio last year all the games I’ve tried have worked flawlessly!

For the curious, the source files for the core are also included on Github.

MiST BBC Repton