On Thu, 2 Jan 2003, Dwight K. Elvey wrote:
> >On Thu, 2 Jan 2003, John Lawson wrote:
> >
> >> On Thu, 2 Jan 2003, Vintage Computer Festival wrote:
> >>
> >> > I've got the PICK CHECK signal from the reader going into CB2. I have
> a
> >> > 1K resistor going from CB2 to ground.
> >> ^^^^^^^^^^^
> >> Try changing to 5K or even 10K (what I always use for pull ups/downs in
> >> TTL work. I think you're burying the poor PICK CHECK signal. Actually
> >> all the resistors oughta be 10K, IMHO.
> >
> >I'll certainly try that. But I'm wondering why that should be necessary
> >when the 6522 data sheet says that particular pin is a TTL level output.
>
> Hi
> I thought you were using the pin as an input. As an input,
> there is no pullup and a floating pin would not be good.
The pin is an input, but it's normal state is to be off/false. Therefore,
John's suggestion to put a pulldown resistor on it seems logical. It
should be normally off, and the M200 should bring it high when it wants to
signal the PICK CHECK error.
I'm trying to troubleshoot a more pressing problem right now: the reader
is picking 5 cards before the Apple thinks 80 Index Marks (e.g. 80
characters) have been detected. Either my code is wrong, my code is slow,
or the Apple is too slow to handle the reader input (in which case this
was all for naught).
I'm heading off to Radio Shack to take a mental break and to get some
resistors and to see if they can offer me more than just blank stares.
Sellam Ismail Vintage Computer Festival
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Received on Thu Jan 02 2003 - 18:03:00 GMT