diskerr

DiskErr is some old fashioned disk editing/repairing stuff, but be warned: With this program you really can harm your disks, so use at your own risk. If you want, you can even save a sector from your floppy to enjoy it in other programs... there is not too much use for it, but it works.

You can see the attached (still pascal) sources, and check the asm hacks to get some stuff of how the hardware is (was) working in the times when there were no open windows around. BTW, there are more sources than required... sorry for not removing them.

One screenshot for you: