QC timing

Gary Melander (garym@onramp.net)
Fri, 5 Jul 1996 14:03:32 -0500 (CDT)


A word for programmers:

I see a lot of renewed interest in the QC for DOS software, and frankly, I'm
a bit suprised at the number of purists out there who are getting
sidetracked with the issue of "Precise" signal timing. I can say with
confidence, there are only two speeds: "About Right", and "Too Damn Fast".
(Guess which one works...)

There is nothing sleazy about burning up a few million CPU cycles with a
non-elegant timer loop. Tweak it till it works, and move on!

I believe the Microcontroller uses an RC circuit for its clock (not a
crystal).... meaning that the signal timing will be different from cam to
cam, port to port, and even from minute to minute, depending on temperature
and relative humidity... I could be wrong, but my hardware tests indicate
there is nothing precise about the handshakes. Hell, they're not even
symmetrical! Signals can be off by a few miliseconds, sometimes even within
a single frame. Remember, this is a parallel port, not serial. No fancy
bit-clocks here...

Gary Melander
Binary Farm