PET Composite Video - test-drb@ccmp.vtda.org

1 Dec 1998

...
  From: Philip.Belben(a)pgen.com
 Subject: Re: PET Video (was: Replacing 6550s) & 128

 Foxnhare (who are you anyway?  I've seen the address before.  You're not
 Larry Anderson by any chance are you? :-) ) wrote: 
Yep, the login was my wife's idea...  Fox: an old definition for my middle
name, Todd, and Hare: for her last name.

...
    From: Doug Spence &lt;ds_spenc(a)alcor.concordia.ca&gt;
 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 think the last batch of 12/24 PCB connectors from them cost me about $18
(for 10).  Very reasonable!

[snip!]
...
  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. 
I would think you could get a multi-sync to do it, but the way the screen
behaves I think the fat-forty and 80000 series were able to change sync rates.
 (Of course what do I know I'm just mainly a software guy).

...
  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. 
Could ya like draw it out or something...  I would really like to have a
composite output on the PET (ohh could do WWW quick-time animated movies of
such classics as Drameda! or Dance! - PET character animated shorts)  100k of
video for a 5K program animation  :)   Actually would be better to screen
capture it off of an emulator and then you can compress it way down to say 60
k or less..

...
  From: ard(a)p850ug1.demon.co.uk (Tony Duell)
 Subject: Re: PET Video (was: Replacing 6550s) & 128

 [Composite video adapter]

  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  
 I've never tried that one. I've used modifications of the TRS-80 Model 1 
 circuit and the BBC micro circuit with no problems at all. The latter is 
 simpler, so I'll describe that. But the output has a little DC offset 
 that some (a _very_ few) monitors object to.

 Start by Xoring HSync and VSync to get a CSync signal. I normally use a 
 74LS86 for this. But the XOR-from-4-NANDs using a 74LS00 once got me out 
 of a hole when I couldn't find any '86s. Invert CSync to give Csync/ 
 using either another section of the '86 or a suitable TTL inverter. 
 Alternatively make an XNOR gate from 4 NORs.

 You now combine video and CSync/ using this circuit 
Or the complete circuit of this?  I would really like to get a composite
circuit for the PET FAQ on-line One could concevably make a portable PET
(yeah, the PET is kinda portable, but not as much as an SX 64 or 128D) if such
a circuit was available.   ;>