WTD: support ICs - test-drb@ccmp.vtda.org

30 Jul 2002

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 From: ard(a)p850ug1.demon.co.uk

 Hi
  I'm always looking for DTL chips. Finding these
 would be great. Anyone with some of these hiding
 away or some old surplus board with them on it,
 I'd be interested. I forget the numbers I need
 but one is a open collector nand ( something like
 935? but that sounds like a RTL). I'll have to make 
It's been a long time, but I thought the 935 was an hex inverter 
(open-collecotr output, of course -- aren't _all_ DTL chips like that). 
The quad 2-input NAND is the 846 (I was repairing a board that used one, 
surrounded by TTL chips, the other day).

Unless the _input_ characteristics are important (they were on this 
board, as the inputs came from RC networks), you can often use the 
equivalent TTL part (open-collector outputs, so something like a '03 for 
the NAND or a '05 for the inverter) with resistor pull-ups (around 3k 
from each output to Vcc). It's not original, but it normally works.

-tony

Hi Tony
 I think the one number I'm thinking of was something38
and not somthing35. Yes, it is true that a TTL will
sub in most cases but there is one that doesn't work
and that is where you have the expanded input ( also one
of the chips I'm looking for ). This was only done
on the DTL and not supported on the TTL of similar
function.
 I have to go back and look to see what the numbers were.
Dwight