While home over the holidays I was interested in seeing what the earliest digital document I could find would be. I think the best contender is this circa-1985 5.25” floppy disk, which probably holds WordStar files:
I have a few machines with disk controllers that can use such a floppy disk drive — the drives themselves go for about $10-$30 on eBay. The problems I’m likely to encounter are both media failure due to physical degradation, and/or random electromagnetic radiation from the sun having flipped some of the bits. Both of these could turn part or all of the files into gibberish. In that case, there’s an modern floppy controller called KryoFlux that hooks up to a modern PC and uses more advanced/heroic techniques to try and read the bad parts of the disk repeatedly, hundreds of thousands of times. With luck, even badly-damaged disks can give up some of their secrets.