What to do with an old PC that can only run DOS
The first thing to do is check that you can boot the PC. If the hard disk has gone faulty
and you can't find a DOS boot disk that works, then use a newer PC to download an MS-DOS 3.3 boot disk image
from the Boot Disk Project then download
WinImage. WinImage can be run for free in demo mode and
allows you to create a boot disk from the DOS 3.3 image file.
If you can now boot your old PC, you're ready to do something with it. But what ??
You could use the old PC to control something if you like experimenting with electronics, or you could
teach yourself about assembly language, or just use the PC for basic
word processing. But whatever you want to do you should be able to find
lots of free DOS software that you download from the internet.