Re: strange Keyboard problem
- From: "BillW50" <BillW50@xxxxxxx>
- Date: Mon, 14 Jun 2010 16:31:26 -0500
William R. Walsh typed on Mon, 14 Jun 2010 09:55:45 -0700 (PDT):
I am so surprised that nobody questioned this statement.
Well, if you're going to be pedantic about it...
"Real keyboards plug into dedicated keyboard ports, and real computers
HAVE dedicated keyboard ports!"
So there you go. Have fun. :-)
I personally see no problems with USB keyboards and mice. No need for
PS/2 style connectors. And I am personally glad there are less and less
of them overtime.
And I have some 10+ year old laptops that only has one PS/2 connector.
Supposedly you can hook up a Y connector and then hook up both a PS/2
keyboard and mouse. Although those Y connectors seemed pretty rare and
are not that easy to fine when I was looking for one way back when.
Maybe they are easier today, I don't know for sure.
And didn't PS/2 ports use the polling method? If so, that is very
inefficient method. And what is the difference between those one PS/2
port laptops that you can plug into either a mouse or a keyboard or
both. But desktop PS/2 ports were specialized and you could not use a
mouse in the keyboard one or the other way around. Why was that?
The first IBM PC used a five-pin DIN keyboard connection, and the
later AT did as well. However, they were electrically different from
one another...a keyboard made for a PC/XT wouldn't work on an AT
unless it were to be rewired. (The difference may have gone deeper
than that, what with differing signalling methods and such, but I
Some keyboards had a switch that could be used to select between PC/XT
and AT modes of operation.
Oh yes, I remember those now. I even had adapters to go from those to
PS/2 now that I recall.
The AT connector was of course later morphed into the PS/2 connector
and as such, you can adapt from one connector type to the other. They
both carry the same signals.
That five pin connector used on the PC/XT, AT and countless clones
also found use as an audio connector, typically on European stereo
Actually I believe everybody except American and Canadians audio
equipment used them. Even my Marantz 4400 (quad) and Kenwood KX-1030
from the late 70's had them too (both made in Japan and I actually
picked them up in Japan too).
At the time, the Elcaset was being released and I really liked them. I
don't think they were ever sold in the US, but maybe just in Japan and
maybe Europe. They were a cross between a tape deck and a cassette. I
didn't buy one because I didn't think they would sell enough to make
enough money off of. I guess I was right because they were not around
for too long. But I really wished they made it because they were really
Although the only problem I had with USB mice and keyboards
were on machines so old now that the BIOS doesn't support them
without a DOS driver.
BIOS support might have been missing, but I actually suspect it was
kept off by default (and for the most part, it probably wouldn't have
worked with anything but the motherboard's built in USB ports--if it
had any that could be used).
The USB 1.0 spec dictates that support for HID class devices is to be
provided. I'm sure that some hardware vendors felt they didn't have to
follow the spec, but it appears (based on personal experimentation
with crusty old hardware) that most did, even if you had to turn the
emulation on in the BIOS setup utility.
My experience with USB mice and keyboards is that it isn't the BIOS that
is the problem for the troublesome. But the devices themselves. As I
seriously think if the device automatically resets themselves when the 5
volts gets reapplied, they always work. Those that doesn't, gets
confused and the device acts dead until you remove the USB connection
and reinsert. That is what I think is the problem anyway. As some
devices never have a problem and some always has a problem. The big test
is trying them on a KMV switch and if they fail, it is the device
Otherwise I find USB mice and keyboards to be far better than
connecting up through the PS/2 ports. As PS/2 ports only supports
only 100ma if I recall correctly.
500mA at 5 volts DC, same as USB. Frequently, you can get more. I've
pulled one amp's worth of current from some keyboard ports on laptops
and desktops alike--and never had a problem. Your mileage could well
vary. Sometimes you can do the same with USB.
Well I don't doubt that you can pull an amp or more. But I am pretty
sure the spec was either 50ma or 100ma. And some manufactures stuck to
this. And mice and keyboards didn't normally have a problem with this.
But before USB, some devices wanted to get power from the PS/2 port
through a pass through connector. Now the problem started.
And one little short and it takes out a surface mounted fuselink on
For USB devices, a short isn't a problem.
That very much depends upon the hardware. Later PS/2 ports are usually
protected by a self-resetting 'polyfuse' or similar device, same as
the USB ports. Even so, an electrical short can be fatal to either. A
fuse won't always save your equipment.
Earlier ones did use "real" fuses...sometimes even a replaceable AGC
fuse was to be found on the motherboard.
Well I don't doubt it. But some used fuselinks soldered in. And many
motherboards have been replaced because of this.
Speaking about motherboards and BIOS. Ever try this trick to reprogram a
Worse, PS/2 ports were not standardized.
Sure they were. You're talking more of a problem with an individual
device that didn't follow or respect the specification. (And yes, I'm
being pedantic now. :-) ) I'm pretty sure you'll find that the
electrical specifications are a standard. I don't know about nor have
I checked to be absolutely certain, but it seems that the spacing and
pitch for a PS/2 port are pretty well standardized across the systems
that have them, whether they are stacked or placed side-by-side.
I dunno, many PS/2 ports wouldn't accept the PS/2 plug from this
wireless keyboard/mouse device. Which is a real shame because it used IR
instead of radio and works past 30 feet away. And I found it very handy
to have around. And it wasn't the sockets that was a problem, but the
hole in the cabinets that was usually too small.
You can find plenty of USB devices that violate standards as well--
cables with two type A connectors on them, devices that utilize more
power than they should, devices that won't work reliably with some USB
Yes this is also true. And USB slimline DVD drives and USB tuners are
usually the worst for demanding far more than 500ma.
Gateway M465e ('06 era) - Windows XP SP3
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