Well, this computer is too old for IDE (but see below). :) Looks like it's something called MFM, driven by an entire expansion card that hooks up to the hard drive. But I get what you mean. My oldest tower is running Windows 2000 (since it has a serial port on the motherboard, it comes in handy... for transferring files to/from the IBM PC.) and that has IDE so I could use that for MS-DOS as well (and would be able to run 90s DOS games etc), I'm sure, but with a ~20 year jump in technology (or about half way between the original IBM PC and today).

Interestingly, https://www.lo-tech.co.uk/wiki/Lo-tech_8-bit_IDE_Adapter_rev... or better yet https://www.lo-tech.co.uk/wiki/Lo-tech_ISA_CompactFlash_Adap... looks like it would work if needed, and then using a CF to IDE adapter like you mentioned.