12 Jul
2018
12 Jul
'18
11:02 a.m.
Hi Chuck
I agree it is easy to convert but I am surprised that a start-up would have the guts to
change the "standard," whether it was Memorex, Potter or Century. I think
before the 33FD Memorex was the market leader but I could be wrong. I've asked some
SA founders the question. Does anyone know any Potter or Century FDD people from the
early 70s?
The early HDD interfaces I am aware of used a control cable with an 8-bit bus and a set of
tag lines to define the bus - much more expensive to implement than the Step In/Step Out.
Regards,
Tom
-----Original Message-----
From: Chuck Guzis [mailto:cclist at sydex.com]
Sent: Wednesday, July 11, 2018 11:38 AM
To: Tom Gardner via cctalk
Subject: Re: An historical nit about FDDs
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