Unknown TI logic series

John Robertson pinball at telus.net
Fri Dec 17 12:26:14 CST 2010

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 :-#)#

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