Jeff Epler Saves Vintage Xerox 820 8" Disks for Future Generations with an Adafruit Floppsy

Also compatible with the popular Greaseweazle, the smart reversed adapter board gets original Xerox drives talking to modern controllers.

Gareth Halfacree
29 days agoRetro Tech / HW101

Jeff Epler has been on a mission of data recovery, attempting to archive the contents of vintage 8" floppy disks from a Xerox 820 Information Processor — a challenge, given that even two-generations-removed 3.5" disk drives are a vanishingly rare sight on computers these days.

"My Xerox 820 CP/M computer has a large external drive enclosure with two 8" SS/DD [Single Sided/Double Density] floppy drives in it," Epler explains. "They have a 'Shugart' interface inside, brought out to a proprietary-but-documented 37-pin D-style connector. I previously made a passive adapter board so that a 'Gotek' floppy drive emulator could replace the drive enclosure, and it worked! (and is a LOT less loud than two 8" floppy drives spinning all the time!)"

Replacing a real floppy drive with a Gotek or similar emulator, which allows disk images to be loaded from solid-state storage such as an SD card or USB flash drive, is a great way to get more life out of a vintage computer system like the Xerox 820 — launched in 1981 for $3,795 for its two-8"-drive configuration and heavily based on the Ferguson Big Board kit computer. There's the issue of going in the other direction, though: using the original floppy drives to create images from real, physical disks.

"[It] got me thinking: could I make a second adapter board that would let me archive 8" floppies," Epler explains. "Then, inspiration struck: I didn't even need a second board design. Instead of fitting a plug ('male') connector on the board's top side, I could simply fit a socket ('female') connector on the board's bottom side. Since I'd gotten five boards in my PCB order, I just had to wait for delivery of the connector and solder everything up."

The resulting reversed connector allows the physical Xerox floppy drives to connect to a modern USB floppy controller such as the flux-sampling Greaseweazle or Adafruit's prototype Floppsy. With suitable software — Epler used the official Greaseweazle software, despite opting for the Floppsy on the hardware side — the 8" disks can be read into images for archival purposes, and to use in emulated form with the more reliable and much quieter Goteks now installed in the Xerox 820's floppy disk housing.

Epler's write-up, which includes a guide to both reading from and writing to original 8" disks, is now available on the Adafruit Learn portal; KiCad design files and Gerbers for the adapter board are available on Epler's GitHub repository under an unspecified license.

Gareth Halfacree
Freelance journalist, technical author, hacker, tinkerer, erstwhile sysadmin. For hire: freelance@halfacree.co.uk.
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