GAL16V8 as a modern substitute for a 7447?

Bob Armstrong bob at jfcl.com
Sat Dec 8 21:21:56 CST 2007


>The good news is that it's easy to prototype one up and
>see how it works on a breadboard.

  Breadboard?  As in hardware?  That's for sissies - we have simulators now
:-)

  FWIW, I tried it and it is possible to fit a decimal counter with seven
segment outputs, a carry out, and a synchronous clear into a single 16V8.
Hint: you have to invert one of the state machine bits, and then invert the
corresponding output pin, but if you do that it'll fit.

  You didn't say whether you need a parallel load (in BCD, presumably) too -
that'd almost certainly be too many AND terms.
 
>True.  Power is not really an issue here.  The LEDs are going to pull
>a fair amount of power on their own, not including counting and driving.

  A 16V8 can use 100mA or so.  How many decades did you say you wanted?
That's gonna add up fast...

Bob




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