MS-Dos for me, don't recall what version or so, but it was the big floppy era at the time, the small shielded ones were a real revolution!
Now the "big floppies" - those were the 8" ones; I never got to use them (but I recently acquired from Ran Talbott a couple of boxes of them - one unopened - for my "museum collection").Does anyone here remember 3 inch microdisks (not 3.5 inch - 3.0 inch!)? They existed and were advertised in many magazines and such around 1984 or so; back when a 5 MB hard drive would set you a few thousand dollars US...
I saw adverts for cutter / jig arrangements to double the capacity of your 5 1/4 disks
HDOS, Heathkit OS for their Z-80 H-89 computer kit.
Now that you've reminded me, I saw adverts for cutter / jig arrangements to double the capacity of your 5 1/4 disks back then. I tried it with some of mine
I found some code in an old COMPUTE! magazine that turns on the "high-res" graphics mode in AppleSoft BASIC if you have the memory for 80-column mode
if you want performance you need to either know apple / 6502 asm
The difficult part, from what I (barely) remember, was that the RAM for video on the Apple IIe was broken up into pages, and they were a) non-contiguous, and b) not an even multiple of bytes for a portion of the screen.