[net.micro.pc] Reset Switch

TRENTHAM%USC-ISIB@sri-unix.UUCP (12/15/83)

From:  Daniel Trentham <TRENTHAM@USC-ISIB>

I had good luck with the following reset scheme	but it does require
some soldering although one could always use E-Z hooks.

First remove the system board from your PC. Then remove the wire from
P1 pin 1.  See sheet 10 of the schematic for the system board in the
technical reference manual.  This wire comes from the power supply and
goes to the system board.  You can use a small screwdriver to depress
the locking pin securing female pin to the connector.  This wire is
the "pwr good" signal from the power supply.

Now solder a small wire (I used 30 Gauge wire-wrap wire) to U11 Pin 11
and to one side of a momentary contact switch.  Solder a second wire
to ground and to the other side of your switch.  You are now all set.

U11, Intel's 8284a, is the clock generator chip which provides a
sync'ed reset as one of its functions.  The RES* input to the 8284A is
a schmitt trigger input.  I didn't use a pull up on it but noted no
bad effects from not having done so.  The synced reset goes to the
8088 which in turn executes the instruction at absolute address FFFF0H
when reset goes away.  This instruction is a "JMP RESET" in the IBM-PC
BIOS.

Daniel

v.cc2%UCLA-LOCUS@sri-unix.UUCP (12/15/83)

From:  Computer Club SDC <v.cc2@UCLA-LOCUS>

I installed a momentary switch to pull the reset line on the 8088 and
it works fine as a reset switch (although it goes through all of the
selftests again!)

A friend of mine got to play with the new Intel 286/310 machine.  It's
pretty cute.  He write a PC emulator to run all, not some, all PC
software.  That includes any graphics stuff.  The emulator runs, get
this, faster than the PC itself!.  That 310 is a *fast* machine.  It's
nice to have 1 giga-byte addressing!.

Howard