John Sanderson wrote:
>
> Dear PIC.ers,
> This is a little off-topic, but I think it will be of interest to a lot of
> us, if only for reference.
> ..
> A client of mine wants to chart the progress of a laboratory
> stress/strain test, for materials QA purposes.
> Initially, he thought an analogue X/Y plotter would be appropriate,
> till he found what that would cost these days. Obsolete approach,  etc.
> Sensibly, he now opts to use a redundant PC (XT or AT) and the 8-bit
> analogue game port available on many cheap combo cards.
>snip<
I remember writing games for PC's the joystick input was the time out
period for a multivibrator and there was a great deal of jitter but it
averaged out OK you will have to convert a varying voltage to a variable
resistance.
PS "scope cards" are less than $100.00 US and give better resolution
multiple inputs and the software will be cheap or bury a PIC inside an
obsolete printer and make your own chart recorder (time/date/ ...!...)
 Tony M.