Who collects (reads the mailing list...?) vintage computers - test-drb@ccmp.vtda.org

16 Oct 2000

From: Richard Erlacher &lt;richard(a)idcomm.com&gt;

...
 Was that uPD 372 the version that handled hard-sectored
diskettes as well?

It could.

...
 I remember they had a uPD 371 as well, but I'm not
remembering whether it
...
 was a tape controller or a hard-sectored disk interface
controller.  I seem
...
 to remember something of that sort being available in
the mid-late '70's.

All the way up to 1980.  I have some 371s too.  makes a fair tape
controller.
Though I found using a 765 or 1793 far easier to use as the old 37x parts
were three voltage nmos and two phase clocks.  They were ok with
systems that had 8080s.

...
 I remember Robert Suding once telling me that the
reason they couldn't do
...
 any better with their FDC's was because the 74S124
(VCO) was too expensive.
...
 Now, I used it from time to time and don't rmember
ever paying more than $2
...
 for one.  Of course, you never know how long before
then the DG people were
...
 trying to buy the things. 

the 74124 was fast enough and pretty cheap.  PLLs using it were a pita.
If you used it there was a lot of other TTL around it so it was not the
cheapest
way to go and often the flakeyest.  A good design with oneshots worked
well enough.  Later one when people figured out how to do a digital
oneshot
or digital PLL then it got real cheap.

Allison