11 Jul
2018
11 Jul
'18
11:38 a.m.
On 07/11/2018 11:12 AM, Tom Gardner via cctalk wrote:
Anyone know where the Step/Direction version of the
FDD interface
originated.
So far as near as I can tell the earliest FDDs (IBM 23FD Minnow and Memorex
650/651) used Step In/Step Out. The IBM 33FD Igar used direct control of the
motor.
The earliest Step/Direction FDD I can find is the Shugart 800 which first
shipped in September 1973.
Shugart is probably it, unless there's a hard drive interface that
precedes it. Mostly a minimal bit of logical difference between the
Step in/Step out and Step/Direction. One can be converted to the other
rather easily.
--Chuck