[Coco] PICs and S-Video

Chris Hawks chawks at dls.net
Thu Feb 23 21:25:34 EST 2006

---Reply to mail from John Kowalski about [Coco] PICs and S-Video

> At 08:07 AM 23/02/2006 -0600, Chris Hawks wrote:
>>    Yeah, that's how it started. But, the 555(6) output is high when the
>>trigger is low (and HSYNC from the Coco3 is a high pulse), so I'll have to
>>invert HSYNC (another chip!) before it's fed to the timer 1. I should
>>be able to de-couple the connection from timer 1 to timer 2 with an RC
> Using one 555 would most likely require an extra inverter, but with the two
> timers on the 556, the 2nd timer on the chip might be used as a way of
> inverting the signal.
> HSYNC in    ________--____________________--____________________--______
> timer 1     __________---------------_______---------------_______------
> timer 2     _________________________--____________________--___________
> (HSYNC out)
> -Timer 1 would trigger when the HSYNC goes low and Timer 1's output would
> remain high for the duration of the delay period.
> -Timer 2 would trigger when the output of Timer 1 goes low and the output
> would be the new delayed HSYNC signal.

    Thats' what I thought 'til I found out that the output will ALLWAYS be
high when the input is low. So the output of timer 1 is not what you show,

timer 1    --------__--------------------__--------------------__---------------

---End reply

Christopher R. Hawks
Any research done on how to efficiently use computers has been long lost
in the mad rush to upgrade systems to do things that aren't needed by
people who don't understand what they are really supposed to do with them.
    -- Graham Reed, in a.s.r.

More information about the Coco mailing list