In message  <199605161848.LAA19162@tidepool.com> PICLIST@MITVMA.MIT.EDU writes:

>         The article went on to suggest that in cases where there did not
> exist any risk to expensive equipment or life-form a WDT was rather useless.

For the last few years, Sharp TV's have included a hardware WDT circuit for
the main control microprocessor. It's quite simple, an output pin is
repeatedly toggled at various points in the program, this produce roughly
a 25Hz squarewave on the pin. This signal is used to charge a capacitor,
which then holds a transistor in the switched off state. If the processor
crashes, the squarewave disappears, and the transistor then turns on - this
is then used to perform a hardware reset via the reset pin.

This prevents any crashes affecting the TV, otherwise you would have to
turn the TV off and back on.

Nigel.

          /----------------------------------------------------------\
          | Nigel Goodwin   | Internet : nigelg@lpilsley.demon.co.uk |
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