> >> Determine the time it takes for the processor to be garaunteed to
> >> have all its volatile RAM fail.
>
> Fail? Do you mean here to have all ram go "clear"?
>
> If so, you will find that you must wait forever. You have no guarantee
that
> the ram will be "clear" (zero, or whatever) at power up.

Well, I said if that time was shorter than the time for it to execute the
clear then it was worth it, but if not, it was not, it appears that the time
for the RAM to clear is longer than the time for the program to run, and
thus the suggestion has no merit.  I thought I had implied that that could
be the case in my post.

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At 03:47 PM 8/20/02 -0700, you wrote:
>Brendan Moran <PICLIST@mitvma.mit.edu> wrote:
>
>> Determine the time it takes for the processor to be garaunteed to
>> have all its volatile RAM fail.

Fail? Do you mean here to have all ram go "clear"?

If so, you will find that you must wait forever. You have no
guarantee that
the ram will be "clear" (zero, or whatever) at power up.

You don't know what ram will be at power up.  This is exactly why
people
who care write routines to clear ram at the beginning of their
programs. Or
set it to some other known state.

A colleague once demonstrated to me how easy it was to write a quick
10
step program and load it into an 1802 processor via a terminal
program.
The target system had a solenoid and his program made it click on/off
at
about a 1Hz rate.  Thinking to clear it from memory, he turned the
power
off for a couple of seconds and back on. The solenoid began to click
again.
The memory had not cleared.

A voltmeter revealed that the ram power had indeed dropped to below
.5
volts but it did not forget.  We tested some more and found that the
power
could be off for over 45 seconds before the program would not run at
power
up, ie, it had scrambled at least one ram location needed for the
program.

Tom M.

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rendan
---
"Rejection out of hand of all but one's favoured alternative may cost you
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