26 Mar
2005
26 Mar
'05
12:50 p.m.
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 :)
--
Jim Leonard (trixter at oldskool.org) http://www.oldskool.org/
Want to help an ambitious games project? http://www.mobygames.com/
Or check out some trippy MindCandy at http://www.mindcandydvd.com/
26 Mar
26 Mar
3:30 p.m.
Jim,
I've never done it, but remembered reading about it. I've looked up the
procedure in Upgrading and Repairing PC's by Mueller.
Find the 8284a (82284 in the AT) timer chip in the PC. When pin 11 is
shorted to ground momentarily it will start the reset process. Also
shorting the "power good" line from the power supply will do the same
thing. The power good pin is supposed to be P8-1.
Whether it's a warm reset or a cold reset depends on the memory contents
of a certain memory location. Doing a Cntrl-Alt-del sets it up for warm
resets from there on out.
If you work with early PC's, Muellers book should be on your list of
books to buy. I actually have 2, but different revisions, since the
contents are a bit different in each.
Chad Fernandez
Michigan, USA
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 :)
3:45 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
27 Mar
27 Mar
1 p.m.
On Sat, 26 Mar 2005 18:50:21 +0100, Jim Leonard <trixter at oldskool.org>
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...
I have a number of reset devices which I made for a special application
(keyboardless PCs), but they only work like a keyboard reset. It is,
actually, a Z8 which pretends to be a keyboard. The early PCs did not like
to start without a keyboard.
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 :)
We had a couple of short power failures some time in the eighties.
One-second dips, any kind of power disturbance was very uncommon here in
Norway, so it was a memorable event. The IBMs and a Commodore PC-20 were
the only PC-type equipment which did not even have a hiccup.
I think they still had properly designed power supplies.
--
-bv
8:52 p.m.
Not too hard. I used to do this all the time. The clock chip actually has a
reset input pin. We used to just slam it to the ground rail but that was
slightly destructive-- better to ground it through a 100 to 500 ohm
resistor or so.
For AT class machines, the clock chip is an 82284 (18-pin dip). For the
5150 I think it's a 8284. Either way, the reset pin is # 11. In a pinch, I
used to used the tip of a screwdriver to short it to the next (pin 10) pin.
At 11:50 AM 3/26/2005 -0600, you 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 :)
--
Jim Leonard (trixter at oldskool.org) http://www.oldskool.org/
Want to help an ambitious games project? http://www.mobygames.com/
Or check out some trippy MindCandy at http://www.mindcandydvd.com/
Success is the ability to go from one failure to another with no loss
of enthusiasm." -- Sir Winston Churchill
--... ...-- -.. . -. ----. --.- --.- -...
tpeters at nospam.mixcom.com (remove "nospam") N9QQB (amateur radio)
"HEY YOU" (loud shouting) WEB ADDRESS http//www.mixweb.com/tpeters
43? 7' 17.2" N by 88? 6' 28.9" W, Elevation 815', Grid Square
EN53wc
WAN/LAN/Telcom Analyst, Tech Writer, MCP, Cisco Certified CCNA
7034
days inactive
7035
days old
4 comments
5 participants
participants (5)
-
bv＠norbionics.com -
cisin＠xenosoft.com -
fernande＠internet1.net -
tpeters＠mixcom.com -
trixter＠oldskool.org