29 Dec
2010
29 Dec
'10
4:19 p.m.
Chuck Guzis wrote:
I think some of the early IBM [8-inch floppy drive]
models (did they ever get into production?)
used 8 sector holes along the outer edge.
The original 8-inch floppy drive was the IBM 23FD "Minnow", which was
used as a read-only device to load microcode into the 3330 controller,
and other System/370 control units and peripherals. Presumably IBM had
special drives in-house for writing the disks sent to customers.
The disks spun at 90 rpm (vs. 36), and used FM encoding at 33.3 Kbps.
They had 32 tracks at 32 tpi (vs 77 tracks at 48 tpi), eight sectors per
track, and the total formatted capacity was 81,664 bytes.