Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!linus!security!genrad!grkermit!masscomp!clyde!floyd!harpo!seismo!hao!hplabs!sri-unix!TRENTHAM@USC-ISIB From: TRENTHAM%USC-ISIB@sri-unix.UUCP Newsgroups: net.micro.pc Subject: Reset Switch Message-ID: <14673@sri-arpa.UUCP> Date: Wed, 14-Dec-83 20:07:00 EST Article-I.D.: sri-arpa.14673 Posted: Wed Dec 14 20:07:00 1983 Date-Received: Tue, 20-Dec-83 01:32:11 EST Lines: 25 From: Daniel Trentham 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