Plummer started his career working as an intern at MS-DOS working for Ben Slivka. He wrote a bunch of major features, like the Smart Drive cache for CD-ROMs.

He wrote DISKCOPY, making it work, single pass, bunch of features in MS-DOS. He re-wrote Setup to work on a single floppy disk by using deltas and patching in place, DOS 5 to turn it into DOS 6, something like, or maybe it was DOS 6 into 6.2.

Plummer said that he did not think there was any reason to hold back any of MS-DOS at this point. They have absolutely no reason not to open source any of it, really — other than PR, because all it brings them is potential liability, complaints and angst, and probably nothing positive for putting the code out there and exposing it to ridicule.

“It's ancient code at this point. It's like, "Ha! Look what Microsoft did!" Well, yeah, I know Linux is cool now, but go look at Linux code from 1991 — and I worked on some of that code. Well, '93 I did. It's not the same as what you see today”, he said.

Plummer said that MS-DOS probably looks archaic — although it's super tight, it doesn't have many bugs.

“It's just written differently than you would write code today, because you're targeting something that is a very different CPU and memory system and PC as a whole, and it's so much more limited that everybody's sacred, every cycle matters. That kind of thing that you don't worry about now. But I'd still like to see all the code from back then that's not embarrassing released”, Plummer said.