"Jan Panteltje" wrote in message
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On a sunny day (Fri, 1 Feb 2013 18:40:50 -0000) it happened "Ian Field"
wrote in :



"Jan Panteltje" wrote in message
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On a sunny day (Fri, 1 Feb 2013 16:55:24 -0000) it happened "Ian Field"
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"Jan Panteltje" wrote in message
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On a sunny day (Fri, 01 Feb 2013 13:17:42 GMT) it happened Jan
Panteltje
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OK, but that is actually an integrated circuit.
Just mis-labeled 'transistor'.
:-)

PS,
some of us here will remember RTL logic.
That was pretty much like that, but more transistors to make gates,
and
output R too.
Integrated circuits.


My first job was component level fault finding on Olympia desk
calculators,
they contained about 4 boards of DTL - a 5th board at the back was
critically sensitive MOS shift registers. The boards were about the same
area as S100, but wider & not so high, the front board had about a dozen
nixie tubes.

I must've just missed out on RTL by not all that long, it was only just
becoming scarce in component catalogues of the day.

DTL was better, it was faster too IIRC.


IIRC the crystal was 3MHz, I assume they'd run the MOS shift registers as
fast as they could get away with - and that would probably be what set the
upper limit.

One shift register recirculated the product of calculations past a row of
TTL 7475s which latched the "correct answer" every time it whizzed past.

I think the BCD to Nixie decoder/drivers were also TTL, the bulk of the
chips (over 200) were DTL.

In the late sixties or maybe very early seventies I build a frequency
counter
with 4790 decade counters, and 7475 latches,
cannot remember the number of the nixie driver chips, also TTL.
It had a 100 kHz crystal as reference, 5 digits, counted up to about 30
MHz,
as that was the maximum where the TTL would still work.


The Nixie drivers in the calculators might have been 8T series - but its a
long time to remember obscure details like that!