160 baud ALDL data - reading on a PC, counter 0?

[Stuart Bunning]

At 09:57 AM 17/6/99 -0400, you wrote:
>Just remember that a PC is a non-real time machine. 

IF YOU ARE DOING YOUR PROGRAM IN DOS YOU CAN MASK OFF ALL THE OTHER
INTERUPTS AND
YOU CAN USE THE PC AS A REAL-TIME DEVICE.. i HAVE DONE IT MYSELF.



>sometimes misses an interrupt or two!
>
>The clock to that timer is based on the original PC's 14.XXXX clock which was
>divided down to feed the CPU clock and video scan generator.  It has been a
>while since I knew the exact numbers for all of that, but I'm not surprised
your
>measurements disagreed with the manual.
>

I HAVNT' DONE ANYTHING LATELY BUT AS FAS AS I WAS AWARE ALL PC'S EVEN NEW
Piii STILL HAVE A 1.19MHZ CLOCK RUNNING THE 8253 TIMER CHIP..

i CANT REMEMBER THE EXACT FIGURES BUT I CAN DIG THEM UP IF NEEDED.
THE xt ORIGIONALL HAS A 14.31818 MHZ XTAL THAT WAS DIVIDED BY 3 TO GET THE
STRANGE 4.77mhz CPU CLOCK SPEED.
THIS EXSACT FREQUENCY WAS CHOSEN SO THAT IS COULD BE DIVIDED TO GET THE
EXACT ntsc COLOR BUTST SIGNAL TO RUN THE cga CARD AND PRODUCE A COLOR
DISPLAY IF USING THE COMPOSITE OUTPUT ON A CGA CARD.

IT WAS DIVIDED DOWN AGAIN TO GET APPROX 1.19 MHZ THAT IS FED INTO THE 8253..
THIS WAS USED FOR IRQ ZERO SYSTEM CLOCK INTERUPT THAT WAS THE HEARTBEAD OF
ALL pc'S NOWADAYS THINGS MAY OF CHANGED IN WINDOWS BUT i THINK NOT..

THIS MAY NOT HELP YOU BUT IT BROUGHT BACK MEMORY'S OF PROGRAMING IN DEBUG
(ASSEMBLER) IN MY YOUNGER DAYS..
I COULDN'T HELP BUT SPILL MY GUTS..

IF YOU WANT TO DO THIS IN WINDOZZZ I CAN'T REALLY HELP ...