Skip to main content

MFM Emulator

Read or emulate old MFM drives for your vintage computer

We’ve gone into regular production of David Gesswein’s MFM Emulator! These are excellent devices, capable of emulating 1-2 MFM disks for many old machines. We’ve had great success with them in PDP-11s, of course, but they’ll also work in a variety of minicomputers and microcomputers, including many unlisted models. Our units include a pre-configured BeagleBone microcontroller and a 4GB microSD card to store your HDD images.

MFM Emulator

Choose between:

  • Original Version

  • Special Edition (2x drive activity LEDs)

Special Edition models come with red LEDs. If you would rather have green LEDs, or no LEDs (if you want to run wires to a faceplate LED), use the “Special instructions for sellerin the Shopping Cart to let us know, for no additional charge.


Render of the MFM Emulator

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

Microcontroller

Compatibility

Fully compatible with BeagleBone Black or Green

Processor

AM335x 1GHz ARM Cortex-A8

Memory

512MB DDR3 RAM

Storage

4GB 3MMC on-board flash storage + 4GB microSD card

Connectivity

  • USB client for power & communications

  • USB host with 4-port hub


Usage & Support

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

Here is the pack-in letter shipped with every unit.

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

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, if using the boards as drive emulators. (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.ooo.

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

First, obtain a minimum 32GB microSD card. Load the SD card with this image 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!


KiCad schematics & gerber file download. And here is the Interactive BOM.

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