Finally managed to back up the hard drive on this Tandy 1000SX, which seems completely functional. It was an in-store management computer for a Texas Radio Shack up until 1995.

So far I've identified the internal Radio Shack inventory application with the complete store inventory, shipment history, reorder history, etc. I believe there's also sales records in here, hard time figuring out exactly how to access it though.

I've also got the internal regional mail archive from 1993 - 1995, which has been some moderately entertaining reading; team meeting format suggestions, looking for old hardware to satisfy service contracts, invitations to team building exercises, it's all rather neat.