JK Flip flop (was: some other crap)

Tony Duell ard at p850ug1.demon.co.uk
Wed Dec 24 13:06:22 CST 2008

> Earliest real refs I have are in the 1965 TI and 1966 Fairchild catalogs, both
> list JK flip-flop ICs.
> They both list JK types in the early RTL families, amongst others.

I suspect the name was fairly well-established by that point. The HP9100, 
which came out about a year afterwards, and which used discrete 
transsitors, contains 2 PCBs of flip-flops. Each PCB cotnains 20 JK 
flip-flops (and a little clock control circuitry), they are essentially 
master-slave JK flip-flops built from 4 transistors.

The transistors are labelled in the etch of the PCB 'J', 'K', 'E', 'F'. 
The 'J' and 'K' transitors are for the input flip-flop (and thus, 
presumabluy, conrrespond to the J and K inputs). The 'E' and 'F' transistors 
are for the output flip-flop, why they have those names and not, say 'Q' 
and something-else I don't know.

Alas since the only info on the intenrals of the 9100 is that obtained by 
lookibng at the machine, I doubt I'll ever work out why 'E' and 'F'


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