PET Video (was: Replacing 6550s) & 128

From: Philip.Belben_at_pgen.com <(Philip.Belben_at_pgen.com)>
Date: Mon Nov 30 11:42:05 1998

Foxnhare (who are you anyway? I've seen the address before. You're not
Larry Anderson by any chance are you? :-) ) wrote:

>> From: Doug Spence <ds_spenc_at_alcor.concordia.ca>
>> Subject: Re: Replacing 6550s
>
>> (I especially find it cool that they list various part numbers for the
>> connector. :) )
>
> Digikey is the best source for inexpensive PET compatible connectors.
> (1-800-DIGI-KEY) along with a ton of other cool parts.
Many thanks for that. I know where to turn next time I'm looking...

>> I just noticed for the first time (!) that the "PARALLEL USER PORT" has
>> pins labeled "T.V. Video", "T.V. Vertical", and "T.V. Horizontal"! Has
>> anyone actually connectd a TV or external monitor to a PET?
>
> There are plans for a composite video converter using those pins in Nick
> Hampshire's PET Revealed, I think it only works on the older 9" screen
pets
> and not the 12" ones. The reason for it being on the user port was for
deaier
> diagnostic testing.
I thought the video signals were there on later machines too, but I can
well believe it might not work on the 12 inch screen models.

My experience is that Nick Hampshire's circuit doesn't work at all. Using
the same two chips, 4011 and 4066, the correct procedure (sorry. The
procedure that worked when I tried it) is to combine the two syncs with the
4011, invert (I think - not sure about this one) with another 4011 gate,
and use that to gate the video using the 4066. Works a treat. They tried
it at school, too (don't know what circuit tho'), and got a grey background
for the white text. I imagine a series capacitor might help, but I've not
tried it.

Philip.
Received on Mon Nov 30 1998 - 11:42:05 GMT