[Coco] CoCo3 PIA?
mark at cloud9tech.com
Thu Jan 4 10:12:55 EST 2007
Where did you get the dated pricing information from? :) I was being
sarcastic on my $0.01 price reference. Where you? :)
If the LSTTL is not being used as the pull up and the 68x21 doesn't
have configurable pullups. How does the circuit guarantee a hi level
for the CoCo3 keyboard interface?
They also wire OR'd the joy ports in as well. Again proving that the A
side port must be pulled hi. What am I missing?
Quoting jdaggett at gate.net:
> On 3 Jan 2007 at 13:30, Mark Marlette wrote:
>> I also noticed that the NAND(IC14) could be using it's inputs to pull
>> the IC5's inputs high. That way Tandy would have had to spend the
>> $0.01 on the pullup resistors. :)
> Back in 1985 time frame resistors would have been in the $0.03 range. I doubt
> that the input to a LSTTL device is used for pullups.
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