2 Jan
2003
2 Jan
'03
6:08 a.m.
On Thu, 2 Jan 2003, Sellam Ismail wrote:
On Thu, 2 Jan 2003, John Lawson wrote:
I would think that you would be better off to use a pull-up resistor when
connecting a TTL output to a MOS input (even a supposedly TTL compatible MOS
input), since even totem-pole TTL outputs are weaker at pulling up than
down. A 1K _pullup_ is fine...
Peter Wallace
On Thu, 2 Jan 2003, Vintage Computer Festival
wrote:
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.
Sellam Ismail Vintage Computer Festival
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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.