17 Dec
2010
17 Dec
'10
6:26 p.m.
Christian Corti wrote:
Hi everyone,
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.
Christian
TI and others often produced "House Numbers" for companies that wanted
to hide the 'real' part numbers of components. I would assume this is
what you have here. Thus the SN1474 may not be a flip-flop (7474) as a
result...they may well have jumbled the numbers around to make it
difficult to copy the circuit.
John :-#)#