Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: $Revision: 1.6.2.13 $; site iuvax.UUCP Path: utzoo!watmath!clyde!akgua!whuxle!spuxll!abnjh!u1100a!pyuxn!pyuxww!gamma!ulysses!mhuxj!ihnp4!inuxc!iuvax!apratt From: apratt@iuvax.UUCP Newsgroups: net.micro.pc Subject: Re: Re: IBM-PC Hardware RESET kluge -> R Message-ID: <1500021@iuvax.UUCP> Date: Thu, 27-Sep-84 15:45:00 EDT Article-I.D.: iuvax.1500021 Posted: Thu Sep 27 15:45:00 1984 Date-Received: Sat, 29-Sep-84 10:27:24 EDT References: <171@alberta.UUCP> Lines: 35 Nf-ID: #R:alberta:-17100:iuvax:1500021:000:1555 Nf-From: iuvax!apratt Sep 27 14:45:00 1984 I installed a reset switch on a PC just a few days ago... I determined a couple of ways of doing it, and the one I chose is probably the worst. a) You could rig a button which forces a parity error, and revector NMI to the keyboard-reset routine. I wanted to do this, but couldn't find the place to force the parity error. NMI is active-high, and when the circuitry is holding the line at ground, it's hard to bring it up to +5 to activate it. b) You could inform the computer that its power is bad. that's what I did, and it works fine. The result is just like cycling power, except you don't have to turn off the power supply. This is especially good if you have a hard disk and don't want to cycle its power. There is a pin coming from the power supply which indicates "power good". If you ground this signal, the entire computer is placed in a RESET state, and, when this signal goes active again, a complete power-up restart is executed. The power-good pin is the one closest to the back of the computer on the motherboard. You can ground it by connecting it (through a normally-open switch) to the fifth or sixth pin of the power supply connection (counting from the back to the front). I'm not exactly sure if this hurts the power supply -- it could. Also, check those pin numbers -- I may remember them wrong. But the thing works, and you don't have to cycle power on the mother board, disk drives, or anything. ---- "Fritz! They've killed Fritz!" -- Allan Pratt ...ihnp4!inuxc!iuvax!apratt