The person who imaged the disks commented on this video exploring 86-DOS 0.11: https://www.youtube.com/watch?v=Zd7T5euID1E

(It's a neat video by the way – he shows how 86-DOS would be used in that state back then by creating a Z80 "Hello World" program in CP-M, copying it over with RDCPM, translating it to 8086 assembly with TRANS, tweaking the source with EDLIN, assembling with ASM and HEX2BIN, and running it.)

I give some detail in my article on the find:

https://www.theregister.com/2024/01/05/oldest_ancestor_of_ms...

Sometimes people don't want others to know how they got it.

This has happened infuriatingly often lately. Some disk image from history just suddenly turns up on github with little knowledge of how it got there.

These are 8" disks, so someone not only found the disks but had the setup to read the disks and dump the binaries.