17 Dec
2010
17 Dec
'10
5:05 p.m.
It's possible these were bulk untested devices that the buyer could then
test and choose those the met their requirements or they had been tested to
a different standard than the usual 74 series.
I have my 1974 TI TTL data books from my design engineer days and there's no
reference to them there.
Regards
?
Rod Smallwood
?
?????
?
-----Original Message-----
From: cctech-bounces at classiccmp.org [mailto:cctech-bounces at classiccmp.org]
On Behalf Of Brent Hilpert
Sent: 11 December 2010 19:12
To: General Discussion: On-Topic and Off-Topic Posts
Subject: Re: Unknown TI logic series
On 2010 Dec 10, at 2:36 AM, Christian Corti wrote:
we've had a look inside our IME 122 calculator and discovered that it
is full of SN14xx logic ICs. They are mainly from TI, but there are
also some from Motorola and others. It seems that they have the same
function and pinout as the SN74xx parts but there must be a difference
since the machine has quite a lot of SN1401 (the SN7401 is a quad
open-collector NAND), but there are no pullup resistors anywhere!
Some of the types are SN1400, SN1401, SN1474, SN1490; the ALU is made
up
of SN1482 and SN1483.
Anyone knows this series? BTW the supply voltage is 5V.
I can't find a reference for those numbers, and I haven't seen them
before, however I have seen TI inexplicably producing series identical
or similar to more-common series, but numbered differently. For
example, the SN3900 and SN4500 series are very similar to more-common
DTL series such as the 700/800/900 series, but I have never seen a
reference for the 3900 or 4500 series in TI databooks. One suggestion
might be they were a 'consumer-grade' series, a step below the standard
commercial-grade stuff.
Found your museum's page here:
http://computermuseum.informatik.uni-stuttgart.de/dev_en/ime_122/
index.html
Is PHxxxx a Philips or Siemens number?
Just some suggestions regarding the 1401 outputs and load resistors:
- make in-circuit measurements between the gate output and Vcc, but
with both polarities on the meter leads. This will sometimes indicate
whether there is a resistive element vs. measuring the semiconductor
junctions.
- look for an unused gate on which to measure R of the output.
- perhaps a bit of poor design and/or they were being used at a slow
enough speed they didn't need pull-ups.