The only question is how much error can he have and still count is
knowing the clock speed.

It would be a lot of work, but one could characterize the watchdog timer
for each chip and revision microchip produces.  Then you simply have to
count how many instruction cycles occur before a watchdog reset.  The
watchdog might allow you to get within 10-20% of the clock frequency on
a chip which is the same type and revision as another chip which has
been previously characterized.  The error would largely be due to
temperature.  Add a known temperature reference to the PIC and you can
get that down a bit.

But I suspect he is expecting a 'computer', and the PIC meets very few
of the common definitions of a computer alone.  He is probably, at
minimum, expecting some sort of stable timing mechanism or frequency,
such as a clock, or the old 18 times per second tick, etc.

-Adam

John Nall wrote:

> A friend of mine, who is a very experienced programmer, but knows nothing
> about PIC's (at least I don't think he does) has offered to make a bet
> with
> me as follows:  He is willing to bet, any amount I want to name, that he
> can write a program which can figure out the clock speed of the
> computer it
> is running on.
>
> To rephrase it, he thinks that he can figure out, in software, the number
> of MIPS of the machine he is running on.
>
> Since he is used to machines that have operating systems, with system
> clocks and that sort of thing available to users, he might be able to
> do it
> on those.  But I do not think there is any way whatsoever on a PIC to do
> this.  (No peripherals -- just the raw chip running, with his program).
>
> However, he is very experienced, and I have lost bets with him
> before.  So
> even thought it seems to me to be a sure thing, I am a bit hesitant to
> bet.  Can any of you experts think of a way to do this????
>
> John
>
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>
>
>

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