You probably have something still running with an ST-225, hooked up to a WD RLL controller to get another 10MB out of it.
Ahhh, the old 20MB Seagates... From before when Seagate "sabotaged" their MFM drives so they wouldn't run reliably with RLL controllers... My first PC Style computer was an Everex Step 20 386. At the time, it was the fastest Intel based system out there... I put in a WD1006V-SR2 RLL controller, a Seagate 4096 (80MB drive, but 120MB RLL) and a Mitsubishi MR-535 65MB drive. Nobody could figure out why I wanted 180MB in a desktop system! But I needed it for working with the SCO Xenix development system AND Informix, as well as making a dual boot system that let me run MS Dos or SCO Xenix.
Mark