Iomec disc drive?

From: Jay Jaeger <cube1_at_charter.net>
Date: Sun Jan 4 21:42:47 2004

Actually, this stuff I am working on (controller and interface) wasn't
actually made by HP, it was made by IOMEC (except for the two interface
cards in the CPU box itself).

Also, hate to contradict folks, but the HP 2114B itself is pretty much all
TTL. A quick look thru the card drawings of the CPU / memory etc.
revealed only 3 CTL chips and 1 DTL chip -- the rest is either 7400 series
TTL or discrete transistors. I may have missed a couple, but it is almost
all TTL (and I had to make some repairs in memory addressing when I first
got it).

Perhaps the HP2114A was different?

The DTL already tripped me up once. I had a J/K flip flop with both Q and
-Q low. Turns out -Q was wired with the output of another gate as an
apparent ECO (wasn't on the schematic). Sigh. At least with TTL you have
the clue of the part being open-collector to help you realize someone did
that. 8^)

Jay



At 12:01 PM 1/4/2004 -0500, Bob Shannon wrote:
>Your in much better shape with a DTL part than if it were CTL!
>
>I'm glad to be wrong on this one. FYI, 2114's use CTL for the vast
>majority of their logic, just like the 2116's.
>
>The '759' segment of the P/N sure looked like a common CTL part (common to
>old HP's anyway).
>
>Jay Jaeger wrote:
>
>>THANKS. Several relevant chips are there. 9094, for example, is
>>DTL. They are intermixed. I don't think I buy the statement made
>>earlier by one party implying that these are emitter source
>>
>>At 09:39 AM 1/2/2004 -0800, Al Kossow wrote:
>>
>>> >
>>>I don't have a reference for exactly "DT uL909759"
>>>
>>>--
>>>
>>>I'm in the process of scanning the 1969 f data book and have finished the
>>>logic part. The scan will be up at
>>>www.bitsavers.org/pdf/fairchild/_dataBooks
>>>later today.
>>
>>
>>---
>>Jay R. Jaeger The Computer Collection
>>cube1_at_charter.net
>>
>>
>

---
Jay R. Jaeger The Computer Collection
cube1_at_charter.net
Received on Sun Jan 04 2004 - 21:42:47 GMT