Iomec disc drive?

From: Bob Shannon <bshannon_at_tiac.net>
Date: Sat Jan 10 08:23:45 2004

Jay Jaeger wrote:

> 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?

Yes, bigtime!

The 2114A is nearly all CTL, very much like the 2116, only a bit slower
and much smaller.

I also have a 2114B, but not the schematics for it. I was not aware it
was mainly TTL based, thats good news to me!


>
>
> 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 Sat Jan 10 2004 - 08:23:45 GMT