Okay, this is pretty cool. My 8086 toy OS running on my old Pentium from an actual floppy disk. 😍 I just love that sound and the feeling of using floppies. This brings back so many memories from my early DOS days.

The cp-unopt program copies a file and intentionally uses small unaligned reads/writes (hopefully triggers more bugs).

The I/O cache works “okay-ish”, I guess. When sha1 runs, it has to do a few reads for the first file and basically none for the second one. Both could have been served entirely from the cache, theoretically. (But even just having an I/O cache in the first place speeds up things dramatically.)

Notice how there’s an EA file. That’s a left-over from OS/2, because I copied some files to the floppy using OS/2. In other words, my FAT12 implementation survives OS/2 writing to it. 🥳 (But I guess it should show up as EA DATA.SF. My current code starts at the left and stops at the first space.)

https://movq.de/v/d4d50d3c74/los86-on-p133-from-floppy-small2.mp4