glen@intelca.UUCP (Glen Shires) (09/25/84)
.
Yes, While developing software for the PC, one often runs a
program that has bugs that send the PC into never-never land
and the only way to restart the system is to power it off/on.
Using an XT with a hard disk, power cycling made me cringe.
So, I added my own hardware reset switch by connecting a
normally open pushbutton switch in series with a 300 ohm
resistor to pins 1 and 6 of P1. P1 is one of the two plugs
that connect the motherboard to the power supply, it is the
rear plug and marked "P1". Pins 1 and 6 are at opposite ends
of this 6 connector plug. This configuration grounds the
PWRGOOD signal of the PC and thus resets the CPU.
Now, not only can I reset the PC without powering on/off, but
also if I tap the switch quickly enough, the PC will do a
quick warm-boot rather than a time-consuming cold-boot that
tests all the RAM. This is because the PC ROMs leave the value
1234h in a special location in RAM. After RESET, if this location
contains 1234h, the memory tests are skipped. If this new RESET
switch is not held down long enough that the DRAMs lose their
contents, this value remains and a warm-boot is performed.
NOTE: Sure, I invented this kluge, but neither I nor my company
take any responsibility for it or any affects it causes!
--
^ ^ Glen Shires, Intel, Santa Clara, Ca.
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\-/ --- stay mellow