On 03/01/2016 18:32, Eric Christopherson wrote:
On Sun, Jan 03, 2016, Adrian Graham wrote:
On 03/01/2016 02:06, "Terry Stewart" <[email protected]> wrote:
It's interesting that none of my present TVs would tune properly to the RF
of the ZX81 but they will with some of the other RF only computers like the
Coco 1 and Atari 400? More circuitry in the latter perhaps...
Going from an old, old memory from when TVs became auto-tune rather than
dial-in or 'press-a-button-and-hold-until-something-happens'
What's this about holding a button?
I recall it was
to do with the 'black level' from the ZX81 in that it was too great and
caused the autotune mechanism to skip it altogether as it wasn't seen as a
useable signal.
Hopefully someone else can elaborate on that.
I dont know abourt the ZX but when I worked on VDUs and wanted a quick
comp output.
I seem to remember you could connect a 560R to positive going TTL video
and a 390R
to negative going TTL mixed sync and you would get 1v comp into 75R.
Rod
