I have an old
IDE drive, it's a Segate 41 MB. It says ST-251, then on a
seperate sticker it says -1 right next to the first one. Serial number is
25534738. It's the large kind, like they had back in the early 80's.
An ST-251-1 isn't an IDE. It's a 40MB half-height 5.25 MFM drive. It'll
run at 1 to 1 (also known as "no") interleave if you can find a fast enough
controller; try an Everex EV-332 with fairly late ROMs.
Um -- very tiny point. The interface is ST-506/412. The _encoding_ is MFM.
Plenty of 5 1/4" form factor drives (such as the ST-238) used RLL encoding,
but the same physical interface...i.e. ST-506/412.
You can tell an IDE because it has one 40-pin cable...the ST-506/412
interface required 2 cables...a 20-pin and a 34 pin. ESDI's (rare) took 2
cables (20 & 34) also.