On 24 Dec 2008 at 10:44, Brent Hilpert wrote:
 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. 
Indeed, my first experiences with building with RTL digital ICs were
with 923 JK flip-flops.  Those were the heady days of a half-adder
being about the most you could find in a package.  Early MOS ICs also
featured T flip-flops, I seem to recall.
Cheers,
Chuck