One of the funnest thing I have ever done with my old clunker of a 486 was to write a Toy OS in TASM. pretty fun if you're really really geeky.(more like a boot loader then an OS though)

Another idea for the thing is to use it as a defecto micro controller, the parallel port can be use to set logic high and low , and you can feed that stuff straight to TTL digital IC's which means you can use it for lots of fun things

But to be honest with a Dead disk drive , And your one Dos version behind not having Interlink on system so you can't even use a Null modem setup for file transfer (although you might have some other type of software on board to do that same thing) your kind of stuck with a system that you can't really do much with. But I'm guessing this is all simple for the nostalgia of it but it be neat if you could make it do something useful for ya.

Just though of something Dos 5.0 iirc introduced Qbasic as part of the Os package, if you don't have any way to setup a null modem connection via some normal dos tools , you could in theroy program a simple setup in qbasic. via open"com:1................"