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MFM Emulator

Read or emulate old MFM drives for your vintage computer

Note: As of 2022-07-29, we continue to have very limited stock of MFM Emulators.


Our production of David Gesswein’s MFM Emulator can emulate 1 or 2 MFM disks for a variety of minicomputers and microcomputers, including many unlisted models. They also read the content off of old drives for emulation and preservation purposes. These new units include a pre-configured BeagleBone microcontroller and a 4GB microSD card, to store your emulated drive images.

MFM Emulator

Due to global supply chain issues, these units have non-standard power regulators equipped. They now come with BeagleBone Black compute modules, featuring a built-in Ethernet jack & mini-USB port for connectivity and microSD and a single USB-A port for increased connectivity.


Specs for EE Nerds

PCB

Material

FR-4 TG130

Approximate Dimensions

146mm x 117mm

Layers

2

PCB Thickness

1.6mm

Copper Weight

1oz

Surface Finish

ENIG-RoHS, blue solder mask

Edge connectors (gold fingers)

ENIG, 45° beveled

Components

Supercapacitors

5x AVX SCCT20B106PRB (10 Farad, -0%/+100%, 2.7V)

Power Regulator

Improved LDO design with reverse-current protection


Usage & Support

All details on general use of the emulator can be found on David Gesswein’s website.

Here is the pack-in letter we ship with every unit.

These boards feature ENIG plating . We recommend leaving ribbon cables connected to the fingers, though ENIG connectors after 100 mate/unmate cycles show almost no wear.

You’ll need to source some MFM drive cables. (These might already be in your vintage computer.) Various retailers carry these for about $10 a set. (We may carry these in the future.)

All units are tested for functionality before leaving our Toronto facility. In case your board arrives damaged, or malfunctions on first use, write us at support@decromancer.ca.

Should you need to reload the BeagleBone boot image, here's the process:

First, obtain a minimum 32GB microSD card. Load the SD card with one of the suitable images using balenaEtcher. Advanced users can also uncompress the file and use dd directly from any UNIX-like system.

Once the microSD card is prepared, remove the BeagleBone from the emulator cape and insert the microSD card into the unit, removing any other card that may be installed for now. Hold down the USER button towards the back of the card - not the POWER or RESET button - while applying power via the micro USB connector.

When the 4 LEDs light, you can release the user button. After about a minute, the LEDs will move to a 'scanning' pattern, the light bouncing back and forth. After another minute or two, the LEDs will extinguish and the BBGW will turn itself off.

Remove the microSD card, and put the MFM emulator cape back on the BeagleBone. Re- install any other microSD card you may be using for drive storage. You're done!


If you are going to use the auto-start functionality, and have a serial number between 070 and 100, please read this blog post.

KiCad schematics & gerber file for the older Special Edition units can be downloaded. And here is the Interactive BOM.

Rev C SE License is under a CC BY-SA 4.0 just like the original.