Computer won't post with my favorite keyboard plugged in.

I have a XT/AT keyboard that I've used for 20 years with many machines. Works extremely well and the layout is what I want.

Just upgraded to a HP Pavilion a6200n. The thing won't post with my favorite keyboard plugged in the PS/2 socket. Just sits there with a black screen.

Swapped keyboards and it works fine. But the keyboard sucks. I've got a bunch of keyboards and they all suck. Keys stick, keys in different locations. My old keyboard works just great.

Any ideas on what I might try to get my old keyboard to work?

Reply to
mike
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Maybe your new machine does not provide the power required by the old workhorse?

As for the keycodes and the protocol, AFAIK they did not change.

petrus bitbyter

Reply to
petrus bitbyter

On Wed, 10 Jul 2013 00:02:29 -0700 mike wrote in Message id: :

If you can't get it to work in the PS/2 port, you could try a PS/2 to USB adapter. While I had nothing but problems with a Belkin one, I've had good luck with this one:

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Reply to
JW

The protocol changed from the original PC (and XT) to the PC/AT. Since then the protocol has not changed. The keycodes have had new ones added for various functions such as sleep, email, etc, but the regular a-z, 0-9, F1-12, etc have not changed since the introduction of the PC/AT.

At one point the connector changed, with the wiring being to different pins, adaptors were easily available.

USB keyboards use the same data, it's now encapsulated in USB data streams.

Geoff.

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Reply to
Geoffrey S. Mendelson

An XT/AT keyboard would have the older "DINnish" plug -- not a PS/2 plug. To the best of my knowledge, they are not compatible. (But I could be wrong, now.)

Why not replace it with a Unicomp "buckling spring" keyboard? That's what I use.

Reply to
William Sommerwerck

Try a different USB port. Unplug other USB devices.

Reply to
dave

Good idea to get a good one. I have many that were $2 each from China bought via eBay. They all worked (although not on MacOS) but seem to burn out after about a month.

Windows recognized them with no trouble, some BIOSes did not recognize them at all, there was no keyboard support until the computer finished booting.

An Office Depot brand one, which cost $10, worked fine in all of those situations the cheap ones did not.

Geoff.

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Geoffrey S. Mendelson,  N3OWJ/4X1GM/KBUH7245/KBUW5379 
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Reply to
Geoffrey S. Mendelson

Thanks, guys for the input. I really don't want to buy yet another keyboard. If I can find one like this with the function keys down the side and the qwerty centered in the frame, it's likely to cost a fortune.

I'm sure I could get used to this new keyboard...I just don't want to My fingers know how to drive this one.

I've got usb adapters too. Had trouble with all of them...mostly with stuff that needed to be done before the system boots.

This old keyboard has worked with many different PS/2 sockets over the years.

Measuring the power consumption is on the todo list.

I'd understand if it didn't work due to insufficient power. But it won't let the computer even POST.

I'll have to make an adapter I can probe.

I've also got several USB keyboards with built-in touchpads. They work well for a while, then just stop. Replugging the USB brings 'em back. I'd like to figger out what's wrong with them too. My workbench doesn't have any place to work a mouse.

Reply to
mike

I've got one though on what your trouble might be:

Way back sometime in the late 80s, early 90s I wrote the code for a few keyboard controllers used in clone PCs. Even though IBM had published a spec. on the timing that keyboards were supposed to meet, many of them didn't even come close. But they all worked with early PC hardware because all they were using was a hardware shift register that was tolerant of a lot of variation. When we used a micro processor (6502 based and 8047(?)) I had to build in a test to try to identify aspects of the signal timing during POST and adapt to whatever keyboard was plugged in. I doubt they go through all that trouble anymore.

You may get lucky and find a particular ps/2 to usb adapter that will work.

If you're real ambitious you could program a PIC or Arduino or something to do the translation for you.

I still have an old favorite keyboard from that era. But at this point, if it ever gave me problems, I think I would just finally toss it.

Reply to
Mark Storkamp

My experience has been that, when I get involved restoring or repairing a favorite thing, it's not long afterward that "something happens" that makes me want to get rid of it or replace it.

Obviously, individual reactions vary. But I warn the OP that this could happen, and his effort to adapt the fave keyboard could turn out to be a waste of time.

Reply to
William Sommerwerck

They are exactly the same electrically, I have adaptors that connect PS/2 keyboards to AT style sockets and others that connect AT style keyboards to PS/2 sockets.

The codes are the same, so you can buy a device that connects a PS/2 keyboard to a USB port. If you have the right adaptor, you can connect an AT keyboard to it.

Geoff.

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Geoffrey S. Mendelson,  N3OWJ/4X1GM/KBUH7245/KBUW5379 
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Reply to
Geoffrey S. Mendelson

Hi Mike,

You say the computer won't even start with the old keyboard plugged in? In that case the RESET line (pin 3 on the DIN plug) is being held low - perhaps a short in the cable, bent pin, etc.

Note that pin 3 is the old Reset line which is no longer used, but this is likely the problem on your machine. Try simply removing the pin (careful, don't break any of the neighbours!) or if you can remove the plastic shell, unsolder or cut the wire to pin 3.

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John :-#)#

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Reply to
John Robertson

Opps! Pin 2, not Pin 3 is reset! (edited above to match)

My bad...

John ;-#)#

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Reply to
John Robertson

Is there an xt/at switch at the bottom of the keyboard? If so try both positions.

Reply to
Sjouke Burry

Double check the both the DIN and PS/2 plugs, checking for bent or broken pins. I've come across PCs in the past where a PS/2 extension cable has been damaged during an office move and caused the same symptoms.

Also, have you double checked that the keyboard still works ok on the old PC or, at least, on another PC.

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Reply to
DaveG

That "Opps" is the reason that breaking a pin would be my very last option. It should not be that difficult to interrupt the reset line on a place and in a way it can be restored if necessary. Very unlikely? You just proved the opposite :)

I too still have an XT/AT-keyboard that works fine so far. It can be switched between XT and AT. Differences are way to large for a simple solution. So the switch instructs the old 8048 to use completely different main program. But the HMOS version of the old 8048 is more powerhungry then the newer CMOS version. Still newer processors has all of the elctronics stuffed inside (except for the LEDs) and requires way less power.

petrus bitbyter

Reply to
petrus bitbyter

That's simple then. Grab a female connector that matches the keyboard, grab a male connector that matches the computer, and wire them up, leaving off the reset line.

Or most keyboards, the cable plugs into a connector inside. So it's easy to cut the wire there. Indeed, at one point I needed a small connector keyboard and didn't have a suitable one, so I was going to take a cable I did have that had the small connector and use it rather than the keyboard's original cable.

If the keyboard really is drawing too much current, then clearly something in the computer is between the +5v line and where the keyboard plugs in. So bypassing that whatever would fix it, if this is the problem.

Michael

Reply to
Michael Black

I've had only one motherboard do that, but I don't remember which one or which keyboard. Every other motherboard I tried that was incompatible caused a "keyboard error press F1 to continue" error message.

Even if your XT/AT keyboard is designed to automatically select XT or AT mode, it may have a jumper inside to set the default mode, or its circuit board may be laid out for a manual XT/AT mode selector switch that was needed by an older version of the firmware. Sometimes you can select the default by soldering a wire between the copper pad meant for the center terminal of the missing switch and one of its other copper pads. Doing that made a couple of my keyboards compatible with certain motherboards, yet the auto-select still worked, but with other keyboards it didn't help at all. If you feel that installing such a wire could short and damage something, use a 200-300 ohm resistor instead.

Places like GeekHack.org and kbdbabel.com have lots of information about keyboards, including some schematics at the latter.

Reply to
larrymoencurly

I forgot to mention: another thing that might help is changing the value of any power-on reset capacitor, especially if your keyboard works when you hit the hardware reset button on your computer.

Reply to
larrymoencurly

If you modify that brandnew machine you will loose all guarantee.

First thing to do is making a breakout cable and measuring the power and reset lines using a voltage meter. Especially looking for differences between the old and the new keyboard. Clock and data lines are important as well but a voltage meter may not do. An o'scope will... If only you have one.

There's one much more complex possibility for the cause of the problem: Noise from the keyboard. Some of that older keyboards are a little bit noisy and maybe the new machines inputs are to sensible. Fighting this problem requires some filtering which in turn requires experience and experiments. There's no general prescription for it.

One thing can be tried easily however: Some ferrite clamp(s) on the keyboard cable. If the keyboard is radiating noise *and* if that noise is picked up by the cable *and* if the computers input(s) cannot handle it *then* you have a good chance to fix the problem with it. Conducted noise cannot be fought this way.

petrus bitbyter

Reply to
petrus bitbyter

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