26 Mar
2005
26 Mar
'05
12:45 p.m.
On Sat, 26 Mar 2005, Jim Leonard wrote:
Has anyone ever wired up a reset button/switch for
their IBM PCs? I find
myself powering down-then-up my 5150 three times a day when all it needs is a
hard reset to reboot a hung machine. I've searched the web and usenet archives
for such a design or specs but haven't found anything. If I could soldier a
few wires to a pushbutton, I feel like I would less harsh to the machine...
Or, does it not really matter? Is it not a big deal to power down, then power
up (after 5 second delay) a 5150 or 5160? I know IBM PCs were built well, but
I am unwilling to find out *how* well :)
Sure
You'll also need to load a tiny bit of code into memory.
If you short the two pins of the ISA bus (one on each side) that are
closest to the bracket, you will generate a non-maskable interrupt.
The IBM 5150 Floppy disk controller has room on the bracket for a small
button (or jack for a button on a cable), and has convenient plate through
holes for the correct pins.
By installing your own TSR nmi handler, you can use a push button
to force a jump to code that you leave in memory. There used to be a
free-ware package called NMIEXIT that would let you stuff any .COM file
into memory and be able to force a jump to it, such as a warm boot,
cold boot, DEBUG.COM, etc. (REAL .COM file, NOT a .EXE that has been
RENAMED into a .COM such as newest DOS .COMs)
Brett Salter (Periscope) made some real nice hardware debuggers using that
technique, with debounce of the button, write protectable RAM, etc.
If you can't find NMIEXIT, remind me on Monday or Wednesday.
--
Grumpy Ol' Fred cisin at xenosoft.com