Byron A Jeff wrote:

> All the other PICs are EPROM based with an algorithm that requires 100
> microsecond (uS) programming pulses.  The problem is that most PCs
> can't easily be pinned down to delays that short.

  Just a little nit-pick, sorry!  The PC is *eminently* capable of doing
this.  A certain variety (not the same as "most") *popular PC operating
system* cannot be pinned down to delays that short with better than 98%
reliability.

  I don't know if I ever posted this as a result of my tests.  I *can*
get this level of reliability on a machine running W95, and with about
4µs jitter (i.e., about 99% of pulses are within 4µs, but the occasional
one is stretched as much as a whole clock tick).  A crude retriggerable
4µs monostable (charge pump) could however be used to overcome this.

  This machine is running an active serial port as well (packet Radio)
which may account for much of the unreliability.  On a quiet machine, it
may work far better again.  Since I am using the System Timer, it is
speed-independent, and may in fact work flwlessly on a Pentium II.

  Pure supposition.
-- 
  Cheers,
        Paul B.