In October 2022, I built a MFM Hard Drive emulator board by David Gesswein, and amazingly the board was able to create a drive image suitable for emulation use.

Due to the way MFM drives work, the hard drive data format is essentially tied to the specific MFM controller.

The hard drive used in the Multibox Computer is a Computer Memories CM-5412, while the drive controller is an Intel iSBC 215. This controller has an odd quirk where it does not format the last cylinder of the drive, which causes the emulation reading script to ignore this part of the drive (see here under iSBC 215).

Below are two varients of drive images. 'HIS3' was the third attempt I made, which includes a file ('extracted_data') that can be used with certain tools like 'strings', but cannot be used for emulation because the missing cylinder data. 'HIS4', my fourth attempt, contains a functional emulation file, but due to the command used, did not generate a file that can be used for investigation like 'HIS3'. This is a limitation of the drive reading code, which means an 'extracted_data' file is not generated.

If anyone wants more details, please contact me!