[personal] Re: PDP-8 on FPGA project & where is Hans Pufal?

[Jim Battle]

> Roy J. Tellason wrote:
>> On Monday 22 December 2008 04:07:10 am Mike Hatch wrote:
>>>> A simple example of the differnce. If you take a D-type flip-flop and
>>>> connect the output to a NOT gate and the output of that back to the D
>>>> input, then you get a divide-by-2-circuit. Feed in a regular clock 
>>>> at one
>>>> frequency and the Q output will toggle at half that frequency. But 
>>>> if you
>>> A clocked JK with the JK held high will perform the same function.
>>
>> As will tying the D input back to not-Q,  which most of them have.  
>> The advantage to using the D-type over the J-K is two fewer package 
>> pins needed,  which may or may not be important to somebody.
>>
>> And what the heck does that J-K stand for,  anyway?

John Kardash invented the JK flip flop.  At least, that is what the prof said back in 1982 
when I was at school.