Building a USB keyboard

[David Abrahams]

I need to build an external USB (or PS2 if that's somehow easier)
computer keyboard around a Dell Inspiron 8100 replacement keyboard.
It's been almost 20 years since I've done any serious hardware
hacking, so I thought I'd ask here about how to approach the problem.
Any help would be deeply appreciated.

This link explains some of the reasons for my quest:
http://groups-beta.google.com/group/comp.sys.laptops/browse_frm/thread/5cb08330a25aa8e4/aeccb13a87a6891a

Also, I have recently bought an Inspiron 9300 into which I'd
ultimately like to transplant one of these other 8100 keyboards (the
9300's keyswitch technology is inferor for my purposes). The
keyboards in the two machines use an incompatible connector and the
signals in the cables do not match up (i.e. even after swapping
connectors the 8100 keyboard won't work in a 9300). It seems rather
unlikely that I'll be able to simply exchange some signals and get a
keyboard that functions in the new laptop, so ultimately I'd like to
build a small circuit to adapt the 8100 to the 9300... that's a much
bigger and more critical project, though, I'm sure.

--
Dave Abrahams
Boost Consulting
www.boost-consulting.com

 

[mike]

David Abrahams wrote:

I need to build an external USB (or PS2 if that's somehow easier)
computer keyboard around a Dell Inspiron 8100 replacement keyboard.
It's been almost 20 years since I've done any serious hardware
hacking, so I thought I'd ask here about how to approach the problem.
Any help would be deeply appreciated.

This link explains some of the reasons for my quest:
http://groups-beta.google.com/group/comp.sys.laptops/browse_frm/thread/5cb08330a25aa8e4/aeccb13a87a6891a

Also, I have recently bought an Inspiron 9300 into which I'd
ultimately like to transplant one of these other 8100 keyboards (the
9300's keyswitch technology is inferor for my purposes). The
keyboards in the two machines use an incompatible connector and the
signals in the cables do not match up (i.e. even after swapping
connectors the 8100 keyboard won't work in a 9300). It seems rather
unlikely that I'll be able to simply exchange some signals and get a
keyboard that functions in the new laptop, so ultimately I'd like to
build a small circuit to adapt the 8100 to the 9300... that's a much
bigger and more critical project, though, I'm sure.

Why not just type on the Dell?
It is possible to use VNC and the network to show your desktop screen on
the laptop. If you just use the keyboard/mouse from the laptop, but
view the desktop screen directly, you avoid all the transmission latency
of the VNC display.

The laptop keyboard is usually just a key matrix. Maybe you can cut up
a PS/2 keyboard, reverse engineer the matrix and make it work. Or just
program a microcontroller to do the interface. But I think you'll find
that it's not worth the effort.
mike

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[petrus bitbyter]

"David Abrahams" <dave@boost-consulting.com> schreef in bericht
news:uacmbckp0.fsf@boost-consulting.com...

I need to build an external USB (or PS2 if that's somehow easier)
computer keyboard around a Dell Inspiron 8100 replacement keyboard.
It's been almost 20 years since I've done any serious hardware
hacking, so I thought I'd ask here about how to approach the problem.
Any help would be deeply appreciated.

This link explains some of the reasons for my quest:
http://groups-beta.google.com/group/comp.sys.laptops/browse_frm/thread/5cb08330a25aa8e4/aeccb13a87a6891a

Also, I have recently bought an Inspiron 9300 into which I'd
ultimately like to transplant one of these other 8100 keyboards (the
9300's keyswitch technology is inferor for my purposes). The
keyboards in the two machines use an incompatible connector and the
signals in the cables do not match up (i.e. even after swapping
connectors the 8100 keyboard won't work in a 9300). It seems rather
unlikely that I'll be able to simply exchange some signals and get a
keyboard that functions in the new laptop, so ultimately I'd like to
build a small circuit to adapt the 8100 to the 9300... that's a much
bigger and more critical project, though, I'm sure.

--
Dave Abrahams
Boost Consulting
www.boost-consulting.com

Dave,

The most drastic solution is is taking the old keyboard, remove its inner
electronics and build a USB circuit instead. AFAIK Cypress was the first one
that offered an USB development kit containing a full description of a
keyboard interface. Others like Microchip and AVR also have micros now that
support USB. It can't be that difficult. Reading a keyboard matrix is
amongst the most basic standard applications for a micro and the USB part is
fully described in the relevant datasheets. But it's a lot of work.

But what about the Inspiron 8100 keyboard? The "standard" AT-keyboard hardly
changed since it was introduced by IBM, neither did the protocol. I still
use a first generation AT-keyboard. A luxuous type that also can be switched
between PC and AT. The only thing I need is an adaptor for the wide DIN to
the small PS2 connection. You can find all about both the keyboards and USB
on the net. Look at
http://www.beyondlogic.org/
for instance. So what's the difference between the Dell keyboard and that
old standard except for the connector? It will be worthwhile to find out
because translating keystroke codes is much less work then designing and
implementing the whole of the keyboardelectronics. Besides you don't have to
destroy the old electronics for it.

petrus bitbyter

 

[Michael Noone]

David Abrahams <dave@boost-consulting.com> wrote in
news:uacmbckp0.fsf@boost-consulting.com:

I need to build an external USB (or PS2 if that's somehow easier)
computer keyboard around a Dell Inspiron 8100 replacement keyboard.
It's been almost 20 years since I've done any serious hardware
hacking, so I thought I'd ask here about how to approach the problem.
Any help would be deeply appreciated.

This link explains some of the reasons for my quest:
http://groups-beta.google.com/group/comp.sys.laptops/browse_frm/thread/
5cb08330a25aa8e4/aeccb13a87a6891a

Also, I have recently bought an Inspiron 9300 into which I'd
ultimately like to transplant one of these other 8100 keyboards (the
9300's keyswitch technology is inferor for my purposes). The
keyboards in the two machines use an incompatible connector and the
signals in the cables do not match up (i.e. even after swapping
connectors the 8100 keyboard won't work in a 9300). It seems rather
unlikely that I'll be able to simply exchange some signals and get a
keyboard that functions in the new laptop, so ultimately I'd like to
build a small circuit to adapt the 8100 to the 9300... that's a much
bigger and more critical project, though, I'm sure.

I wouldn't be surprised if the cable coming from a laptop's keyboard is
essentially a PS/2 interface except with parallel data. I remember looking
at the one on my laptop a while ago and it had something along the lines of
11 pins or so - which would translate to 8 data, 1 gnd, 1 vcc, 1 clock.
Might be worth looking into. Otherwise I'd just reccomend taking the
electronics out of a full sized keyboard and attaching them to the keyboard
matrix. Good luck.

-M. Noone

 

[David Abrahams]

mike <spamme0@netscape.net> writes:

David Abrahams wrote:
I need to build an external USB (or PS2 if that's somehow easier)
computer keyboard around a Dell Inspiron 8100 replacement keyboard.
It's been almost 20 years since I've done any serious hardware
hacking, so I thought I'd ask here about how to approach the problem.
Any help would be deeply appreciated.
This link explains some of the reasons for my quest:
http://groups-beta.google.com/group/comp.sys.laptops/browse_frm/thread/5cb08330a25aa8e4/aeccb13a87a6891a
Also, I have recently bought an Inspiron 9300 into which I'd
ultimately like to transplant one of these other 8100 keyboards (the
9300's keyswitch technology is inferor for my purposes). The
keyboards in the two machines use an incompatible connector and the
signals in the cables do not match up (i.e. even after swapping
connectors the 8100 keyboard won't work in a 9300). It seems rather
unlikely that I'll be able to simply exchange some signals and get a
keyboard that functions in the new laptop, so ultimately I'd like to
build a small circuit to adapt the 8100 to the 9300... that's a much
bigger and more critical project, though, I'm sure.


Why not just type on the Dell?

You mean the 8100, obviously. The 9300 is also a Dell laptop.

a. I bought the 9300 for its 17" screen among other things.

b. The 8100's 15" screen would obscure the 20" LCD monitor on my
desktop. I actually worked that way for a while, with the 8100's
screen tucked between the bottom of the 21" screen and its base.
It's kind of a mess.

c. The idea of soaking that much power continuously just to have the
8100 act as an expensive keyboard doesn't appeal to me. That said,
I want to run Linux on it anyway...

It is possible to use VNC and the network to show your desktop
screen on the laptop.

Yep, I'm familiar with VNC.

If you just use the keyboard/mouse from the laptop, but view the
desktop screen directly, you avoid all the transmission latency of
the VNC display.

Well now, that's starting to sound fiendishly clever. I was going to
ask how to make the 8100 send USB keyboard signals so I could plug it
directly into the 9300, but this solution is all done in software.
Nice!

Maybe I can find a used Dell with the same keyboard but whose screen
is smaller and won't be as much of an obstacle.

The laptop keyboard is usually just a key matrix.

Meaning that each key is just a switch that connects a different pair
of wires on the keyboard cable to one another?

Maybe you can cut up a PS/2 keyboard, reverse engineer the matrix
and make it work. Or just program a microcontroller to do the
interface. But I think you'll find that it's not worth the effort.

Well, the one significant issue that still remains is that I want to
use the 9300 away from my desk (or why bother with laptops, after
all?), so I still want to get a keyboard I can tolerate into its case.

Thanks, you've been very helpful!

--
Dave Abrahams
Boost Consulting
www.boost-consulting.com

 

[David Abrahams]

"petrus bitbyter" <pieterkraltlaatditweg@enditookhccnet.nl> writes:

Dave,

The most drastic solution is is taking the old keyboard, remove its inner
electronics and build a USB circuit instead. AFAIK Cypress was the first one
that offered an USB development kit containing a full description of a
keyboard interface. Others like Microchip and AVR also have micros now that
support USB. It can't be that difficult. Reading a keyboard matrix is
amongst the most basic standard applications for a micro and the USB part is
fully described in the relevant datasheets. But it's a lot of work.

I was afraid of that.

But what about the Inspiron 8100 keyboard? The "standard" AT-keyboard hardly
changed since it was introduced by IBM, neither did the protocol. I still
use a first generation AT-keyboard. A luxuous type that also can be switched
between PC and AT. The only thing I need is an adaptor for the wide DIN to
the small PS2 connection. You can find all about both the keyboards and USB
on the net. Look at
http://www.beyondlogic.org/
for instance. So what's the difference between the Dell keyboard and that
old standard except for the connector?

Mechanically? Just about everything.

Electrically? Well, from the articles at the link you cite, it looks
like the old AT keyboard has some active electronics in it, with a
serial output interface. I strongly suspect that these laptop
keyboards are completely passive switch matrices that just complete a
circuit between different pairs of wires on their connector cables. I
can see almost the whole keyboard mechanism and there really isn't any
room for electronics in there.

It will be worthwhile to find out because translating keystroke
codes is much less work then designing and implementing the whole of
the keyboardelectronics.

True.

Besides you don't have to destroy the old
electronics for it.

I was planning to buy one or two Dell i8100 replacement keyboards for
this project rather than hack up the one in my old laptop.

--
Dave Abrahams
Boost Consulting
www.boost-consulting.com

 

[David Abrahams]

Michael Noone <mnoone.uiuc.edu@127.0.0.1> writes:

David Abrahams <dave@boost-consulting.com> wrote in
news:uacmbckp0.fsf@boost-consulting.com:



I need to build an external USB (or PS2 if that's somehow easier)
computer keyboard around a Dell Inspiron 8100 replacement keyboard.
It's been almost 20 years since I've done any serious hardware
hacking, so I thought I'd ask here about how to approach the problem.
Any help would be deeply appreciated.

This link explains some of the reasons for my quest:
http://groups-beta.google.com/group/comp.sys.laptops/browse_frm/thread/
5cb08330a25aa8e4/aeccb13a87a6891a

Also, I have recently bought an Inspiron 9300 into which I'd
ultimately like to transplant one of these other 8100 keyboards (the
9300's keyswitch technology is inferor for my purposes). The
keyboards in the two machines use an incompatible connector and the
signals in the cables do not match up (i.e. even after swapping
connectors the 8100 keyboard won't work in a 9300). It seems rather
unlikely that I'll be able to simply exchange some signals and get a
keyboard that functions in the new laptop, so ultimately I'd like to
build a small circuit to adapt the 8100 to the 9300... that's a much
bigger and more critical project, though, I'm sure.


I wouldn't be surprised if the cable coming from a laptop's keyboard is
essentially a PS/2 interface except with parallel data. I remember looking
at the one on my laptop a while ago and it had something along the lines of
11 pins or so - which would translate to 8 data, 1 gnd, 1 vcc, 1
clock.

I have a box of 50 discarded Dell laptop keyboards downstairs right
now. I've never seen anything that looked like an IC in any of them,
so it seems unlikely that there's any encoding going on in there at
all.

Might be worth looking into. Otherwise I'd just reccomend taking the
electronics out of a full sized keyboard and attaching them to the keyboard
matrix.

Yeah, but just how to attach?

Good luck.

Thanks!

--
Dave Abrahams
Boost Consulting
www.boost-consulting.com

 

[Jonathan Kirwan]

On Tue, 31 May 2005 14:30:19 -0400, David Abrahams
<dave@boost-consulting.com> wrote:

I need to build an external USB (or PS2 if that's somehow easier)
computer keyboard around a Dell Inspiron 8100 replacement keyboard.
It's been almost 20 years since I've done any serious hardware
hacking, so I thought I'd ask here about how to approach the problem.
Any help would be deeply appreciated.

This link explains some of the reasons for my quest:
http://groups-beta.google.com/group/comp.sys.laptops/browse_frm/thread/5cb08330a25aa8e4/aeccb13a87a6891a

What I gather from this is that you really like these keyboards. I
don't know a think about "Inspiron 8100" replacement keyboards,
though, except that they are for laptops?

If they are anything like those I find on my IBM A21P laptop, they pop
out and push back into a system base that is 1/2 of a "clam shell"
unit. Which means to me that you will need to keep the base of some
system as your mechanical support. Otherwise, you'd have to
completely fabricate some kind of comfortable fixture and that sounds
very difficult to me. So do you already have a base that you can gut
and use to complete the mechanical whole on which the keyboard unit
would only a part?

Also, I have recently bought an Inspiron 9300 into which I'd
ultimately like to transplant one of these other 8100 keyboards (the
9300's keyswitch technology is inferor for my purposes). The
keyboards in the two machines use an incompatible connector and the
signals in the cables do not match up (i.e. even after swapping
connectors the 8100 keyboard won't work in a 9300). It seems rather
unlikely that I'll be able to simply exchange some signals and get a
keyboard that functions in the new laptop, so ultimately I'd like to
build a small circuit to adapt the 8100 to the 9300... that's a much
bigger and more critical project, though, I'm sure.

Does the 9300 offer a "standard" external keyboard connector? If so,
if you can adapt your 8100 base and keyboard and write the necessary
micro code so that it behaves as a proper keyboard, you could simply
connect it as an external keyboard to the 9300. Not that this would
be as good as replacing the keyboard, itself.

You mention that the connectors don't match up, but does the 8100
keyboard mechanically screw down properly to the 9300 system unit?

Jon

 

[David Abrahams]

Jonathan Kirwan <jkirwan@easystreet.com> writes:

On Tue, 31 May 2005 14:30:19 -0400, David Abrahams
dave@boost-consulting.com> wrote:

I need to build an external USB (or PS2 if that's somehow easier)
computer keyboard around a Dell Inspiron 8100 replacement keyboard.
It's been almost 20 years since I've done any serious hardware
hacking, so I thought I'd ask here about how to approach the problem.
Any help would be deeply appreciated.

This link explains some of the reasons for my quest:
http://groups-beta.google.com/group/comp.sys.laptops/browse_frm/thread/5cb08330a25aa8e4/aeccb13a87a6891a

What I gather from this is that you really like these keyboards.

You catch on fast, my friend ;-)

I don't know a think about "Inspiron 8100" replacement keyboards,
though, except that they are for laptops?

Yes. They are a replacement part for the keyboard in a Dell Inspiron
8100 laptop.

If they are anything like those I find on my IBM A21P laptop, they pop
out and push back into a system base that is 1/2 of a "clam shell"
unit. Which means to me that you will need to keep the base of some
system as your mechanical support.

That's the least of my problems.

Otherwise, you'd have to completely fabricate some kind of
comfortable fixture and that sounds very difficult to me. So do you
already have a base that you can gut and use to complete the
mechanical whole on which the keyboard unit would only a part?

Yes, or I can get one. IBM makes an external keyboard for their
thinkpads that has the same key layout as Dell laptops, and the
enclosure should accept whatever Dell KB I decide to stick in there.
Unfortunately, if it uses the same key *mechanism* as recent thinkpads,
it's not the one I like right out-of-the-box, so I _would_ have to
adapt the keyboard.

Also, I have recently bought an Inspiron 9300 into which I'd
ultimately like to transplant one of these other 8100 keyboards (the
9300's keyswitch technology is inferor for my purposes). The
keyboards in the two machines use an incompatible connector and the
signals in the cables do not match up (i.e. even after swapping
connectors the 8100 keyboard won't work in a 9300). It seems rather
unlikely that I'll be able to simply exchange some signals and get a
keyboard that functions in the new laptop, so ultimately I'd like to
build a small circuit to adapt the 8100 to the 9300... that's a much
bigger and more critical project, though, I'm sure.

Does the 9300 offer a "standard" external keyboard connector? If so,
if you can adapt your 8100 base and keyboard and write the necessary
micro code so that it behaves as a proper keyboard, you could simply
connect it as an external keyboard to the 9300. Not that this would
be as good as replacing the keyboard, itself.

Yes, that's part of the plan of course, but when I travel around (the
house or the country) with my 9300 I'd like the internal KB to be
comfortable, too.

You mention that the connectors don't match up, but does the 8100
keyboard mechanically screw down properly to the 9300 system unit?

Not quite, but the amount of adaptation needed to get it to work would
be minor.

Thanks for your reply.

--
Dave Abrahams
Boost Consulting
www.boost-consulting.com

 

[Jonathan Kirwan]

On Wed, 01 Jun 2005 09:52:47 -0400, David Abrahams
<dave@boost-consulting.com> wrote:

Jonathan Kirwan <jkirwan@easystreet.com> writes:

On Tue, 31 May 2005 14:30:19 -0400, David Abrahams
dave@boost-consulting.com> wrote:

I need to build an external USB (or PS2 if that's somehow easier)
computer keyboard around a Dell Inspiron 8100 replacement keyboard.
It's been almost 20 years since I've done any serious hardware
hacking, so I thought I'd ask here about how to approach the problem.
Any help would be deeply appreciated.

This link explains some of the reasons for my quest:
http://groups-beta.google.com/group/comp.sys.laptops/browse_frm/thread/5cb08330a25aa8e4/aeccb13a87a6891a

What I gather from this is that you really like these keyboards.

You catch on fast, my friend ;-)

I don't know a think about "Inspiron 8100" replacement keyboards,
though, except that they are for laptops?

Yes. They are a replacement part for the keyboard in a Dell Inspiron
8100 laptop.

okay.

If they are anything like those I find on my IBM A21P laptop, they pop
out and push back into a system base that is 1/2 of a "clam shell"
unit. Which means to me that you will need to keep the base of some
system as your mechanical support.

That's the least of my problems.

Just trying to make sure I "get it."

Otherwise, you'd have to completely fabricate some kind of
comfortable fixture and that sounds very difficult to me. So do you
already have a base that you can gut and use to complete the
mechanical whole on which the keyboard unit would only a part?

Yes, or I can get one. IBM makes an external keyboard for their
thinkpads that has the same key layout as Dell laptops, and the
enclosure should accept whatever Dell KB I decide to stick in there.
Unfortunately, if it uses the same key *mechanism* as recent thinkpads,
it's not the one I like right out-of-the-box, so I _would_ have to
adapt the keyboard.

Back to the 8100 keyboard, then.

Also, I have recently bought an Inspiron 9300 into which I'd
ultimately like to transplant one of these other 8100 keyboards (the
9300's keyswitch technology is inferor for my purposes). The
keyboards in the two machines use an incompatible connector and the
signals in the cables do not match up (i.e. even after swapping
connectors the 8100 keyboard won't work in a 9300). It seems rather
unlikely that I'll be able to simply exchange some signals and get a
keyboard that functions in the new laptop, so ultimately I'd like to
build a small circuit to adapt the 8100 to the 9300... that's a much
bigger and more critical project, though, I'm sure.

Does the 9300 offer a "standard" external keyboard connector? If so,
if you can adapt your 8100 base and keyboard and write the necessary
micro code so that it behaves as a proper keyboard, you could simply
connect it as an external keyboard to the 9300. Not that this would
be as good as replacing the keyboard, itself.

Yes, that's part of the plan of course, but when I travel around (the
house or the country) with my 9300 I'd like the internal KB to be
comfortable, too.

Meaning that its keyboard is replaced by an 8100 keyboard, I take it.

You mention that the connectors don't match up, but does the 8100
keyboard mechanically screw down properly to the 9300 system unit?

Not quite, but the amount of adaptation needed to get it to work would
be minor.

Well, regarding making an 8100 keyboard that would plug into a
standard keyboard port on a laptop or desktop (non-USB), you certainly
could make up a circuit for the 8100 and write the software to get the
job done. An investment, to be sure. But it could be fun. I did
something like this, many years ago, in adapting an IBM Electronic 85
typewriter as a printer device, scoping out the reed-relay events when
I pressed keys on it and developing a schematic and physical circuit
that I built and attached to it that would accept serial port data and
type it out as a printer. The software worked great and I used it for
years. In the case of the 8100 keyboard, you'll need to figure out
the wires (should be a modest, tolerable effort here) and then
familiarize yourself with how to scan them properly and handle things
like n-key rollover, etc. Then write the software to handle the
keyboard interface you'll also design for it. Work, perhaps. But it
really sounds like satisfying work.

I can help inform you about the details of acting like a keyboard.
There are also docs on the web to help, as well.

Regarding adapting an 8100 for use as an integral part of a 9300, the
place I'd start is in figuring out the wiring of the 9300 keyboard
connector and then also the wiring of the 8100 keyboard connector. I
suspect that you'll find these to be logically equivalent (as a wild
guess), though not mechanically equivalent at the connector. If it
works out that way, you merely need to rewire the connector on the
8100 so that it actually uses a proper 9300 connector (you'll need to
find one or scavenge the one on your 9300 keyboard.) Then deal with
the mechanical vagaries of placing it.

If it turns out that there is no equivalent remapping of the connector
wiring, then you may be stuck writing some kind of Windows or Linux
driver that remaps the received (incorrect) key events into correct
ones. Even if the key scanning cannot be exactly wired the same, some
kind of scanning will take place by the existing software that does
this job so remapping may be all that is needed.

This assumes, of course, that the 9300 system board does actually scan
the keyboard. If there is software and intelligence in the keyboard
itself, there may be further complexities.

I think you should start, though, by figuring out exactly what the
8100 keyboard actually does. A lot of "ifs" can be removed from the
table by knowing more about it. Then figure out the 9300 keyboard,
too.

Jon

 

[David Abrahams]

Jonathan Kirwan <jkirwan@easystreet.com> writes:

Yes, that's part of the plan of course, but when I travel around (the
house or the country) with my 9300 I'd like the internal KB to be
comfortable, too.

Meaning that its keyboard is replaced by an 8100 keyboard, I take it.

Seems like my only alternative.

You mention that the connectors don't match up, but does the 8100
keyboard mechanically screw down properly to the 9300 system unit?

Not quite, but the amount of adaptation needed to get it to work would
be minor.

Well, regarding making an 8100 keyboard that would plug into a
standard keyboard port on a laptop or desktop (non-USB), you certainly
could make up a circuit for the 8100 and write the software to get the
job done. An investment, to be sure. But it could be fun. I did
something like this, many years ago, in adapting an IBM Electronic 85
typewriter as a printer device, scoping out the reed-relay events when
I pressed keys on it and developing a schematic and physical circuit
that I built and attached to it that would accept serial port data and
type it out as a printer. The software worked great and I used it for
years. In the case of the 8100 keyboard, you'll need to figure out
the wires (should be a modest, tolerable effort here) and then
familiarize yourself with how to scan them properly and handle things
like n-key rollover, etc. Then write the software to handle the
keyboard interface you'll also design for it. Work, perhaps. But it
really sounds like satisfying work.

Actually the 9300 is scanning a similar (but different) matrix and
doing the rollover support itself, so I doubt I'd have to deal that
explicitly. I think I'd just need to translate the connectivity of
the 8100 keyboard into whatever the 9300 expects.

I can help inform you about the details of acting like a keyboard.
There are also docs on the web to help, as well.

Regarding adapting an 8100 for use as an integral part of a 9300, the
place I'd start is in figuring out the wiring of the 9300 keyboard
connector and then also the wiring of the 8100 keyboard connector.

Yep. A continuity tester should be enough.

I
suspect that you'll find these to be logically equivalent (as a wild
guess), though not mechanically equivalent at the connector. If it
works out that way, you merely need to rewire the connector on the
8100 so that it actually uses a proper 9300 connector (you'll need to
find one or scavenge the one on your 9300 keyboard.)

Finding the connector is easy; I have a box of 50 scavenged Dell KBs.
I put one of the 9300-style connectors on the 8100 KB cable and hooked
it up, but only a few keys did anything and then they typed the wrong
characters. So if the wires are equivalent in some way, they're
scrambled.

Then deal with the mechanical vagaries of placing it.

Really, that's not a problem. They're the same shape modulo a few
tabs and other stabilizing details.

If it turns out that there is no equivalent remapping of the connector
wiring, then you may be stuck writing some kind of Windows or Linux
driver that remaps the received (incorrect) key events into correct
ones.

Heh. I'd rather do it in software than in hardware, but since the
electronics in the computer are probably just detecting *connectivity*
it seems unlikely to be possible.

Even if I could write a driver I doubt I'd be able to operate the BIOS
from the 8100 KB, because the driver wouldn't be loaded yet, right?

Even if the key scanning cannot be exactly wired the same, some
kind of scanning will take place by the existing software that does
this job so remapping may be all that is needed.

That would be ideal.

This assumes, of course, that the 9300 system board does actually scan
the keyboard. If there is software and intelligence in the keyboard
itself, there may be further complexities.

These KBs have no space for electronics. I'm pretty sure they're
completely passive.

I think you should start, though, by figuring out exactly what the
8100 keyboard actually does. A lot of "ifs" can be removed from the
table by knowing more about it. Then figure out the 9300 keyboard,
too.

Makes sense. Thanks for the pointers.

--
Dave Abrahams
Boost Consulting
www.boost-consulting.com

 

[mike]

David Abrahams wrote:
snip

Finding the connector is easy; I have a box of 50 scavenged Dell KBs.
I put one of the 9300-style connectors on the 8100 KB cable and hooked
it up, but only a few keys did anything and then they typed the wrong
characters. So if the wires are equivalent in some way, they're
scrambled.

If you can get any of the keys to work, you're on the right track.

Stick your oscilloscope on the connector to determine which are the
scan output signals. Map out the key matrix on the keyboard. I believe
that there may be a reasonable pin swapping that can make all the keys
work. Isn't there a utility built into the OS that lets you remap keys?
Use that to make the keys to the right thing. But Murphy probably has a
summer home in your keyboard and you'll have grief with things like
ctrl-alt-delete and keys that don't map one for one into a function.

I once built a keyboard for a moving message sign.
Had to find an XT keyboard that still had a circuit board under the
keys. Cut a zillion traces and rewired the whole matrix to to what the
sign needed. This won't work with a plated plastic keyboard.
mike





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[David Abrahams]

mike <spamme0@netscape.net> writes:

David Abrahams wrote:
snip
Finding the connector is easy; I have a box of 50 scavenged Dell KBs.
I put one of the 9300-style connectors on the 8100 KB cable and hooked
it up, but only a few keys did anything and then they typed the wrong
characters. So if the wires are equivalent in some way, they're
scrambled.

If you can get any of the keys to work, you're on the right track.
Stick your oscilloscope on the connector

Hehehehe... haven't seen a sillyscope in years. I have a continuity
tester at my disposal

to determine which are the scan output signals.

I wouldn't know an input from an output. If it's just a switch
matrix, it's going to connect pairs of wires and there's no particular
way to tell which are sending and which are receiving... or did you
mean for me to monitor the signals coming from the laptop's side of
the connector?

Map out the key matrix on the keyboard. I believe that there may be
a reasonable pin swapping that can make all the keys work.

That would be wonderful.

Isn't there a utility built into the OS that lets you remap keys?

Yeah, there's _something_. At least, you can download software that
lets you do some mapping, so I should be able to figure out how to do
it myself if necessary.

Use that to make the keys to the right thing.

Uhh, I dunno about that part. If it's just a switch matrix, the
keyboard isn't sending scan codes. Seems to me if pins are swapped
I'm not going to get anything without un-swapping them... or are you
suggesting that I swap pins until everything does *something*, and
then straighten out *what* it does in software?

Might work, but I might just as easily end up with 2 keys typing the
same character and indistinguishable from the mapper's point of view.

But Murphy probably has a summer home in your keyboard and you'll
have grief with things like ctrl-alt-delete and keys that don't map
one for one into a function.

Could be.

I once built a keyboard for a moving message sign. Had to find an
XT keyboard that still had a circuit board under the keys. Cut a
zillion traces and rewired the whole matrix to to what the sign
needed. This won't work with a plated plastic keyboard.

Probably not. I have plenty of trash KBs to experiment with, though.

--
Dave Abrahams
Boost Consulting
www.boost-consulting.com

 

[Alan Adrian]

"mike" <spamme0@netscape.net> wrote in message
news:429E1371.1020903@netscape.net...

I once built a keyboard for a moving message sign.
Had to find an XT keyboard that still had a circuit board under the keys.
Cut a zillion traces and rewired the whole matrix to to what the
sign needed. This won't work with a plated plastic keyboard.
mike

On a simular note... I've saved the keyboard out of a Toshiba 286 luggable
computer... beautiful thing... it even has a keypad on one end... couldn't
stand to throw it away...

It's got a 22 pin ribbon cable coming out of it and the only semiconductors
on it seem to be diodes... (though I haven't looked on the key-side of the
board, everything sticks through it and is soldered on the back... ahh..
memories... =)

I may want to hook this up to a microcontroller one day or something... (I
play with electronics a bit)... How do I go about mapping this thing out?
It seems rather tedious hooking a meter up to every two pins, pressing all
the keys each time, and making notes...

Al...

 

[David Abrahams]

"Alan Adrian" <ara__@SPAMNOT.wanadoo.nl> writes:

"mike" <spamme0@netscape.net> wrote in message
news:429E1371.1020903@netscape.net...

I once built a keyboard for a moving message sign.
Had to find an XT keyboard that still had a circuit board under the keys.
Cut a zillion traces and rewired the whole matrix to to what the
sign needed. This won't work with a plated plastic keyboard.
mike


On a simular note... I've saved the keyboard out of a Toshiba 286 luggable
computer... beautiful thing... it even has a keypad on one end... couldn't
stand to throw it away...

It's got a 22 pin ribbon cable coming out of it and the only semiconductors
on it seem to be diodes... (though I haven't looked on the key-side of the
board, everything sticks through it and is soldered on the back... ahh..
memories... =)

I may want to hook this up to a microcontroller one day or something... (I
play with electronics a bit)... How do I go about mapping this thing out?
It seems rather tedious hooking a meter up to every two pins, pressing all
the keys each time, and making notes...

Yeah, this is going to take me forever. I tried, but even getting
started is so difficult that I can't see my way to the end. It's hard
to manage the tester leads, and it's an N^2 operation for each key you
want to test.

I've started trying to hunt down information from the keyboard
manufacturers, but that seems like a long shot at best. I think the
9300's keyboard is made by NMB, but they don't seem to want to talk to
anyone but volume buyers for over 2500 units. I can't find anything
that looks like a manufacturer name on the 8100 keyboard.

Anyone have a line on schematics or detailed technical specs for these
things?

--
Dave Abrahams
Boost Consulting
www.boost-consulting.com

 

[Alan Adrian]

"David Abrahams" <dave@boost-consulting.com> wrote in message
news:umzq3fu4w.fsf@boost-consulting.com...

"Alan Adrian" <ara__@SPAMNOT.wanadoo.nl> writes:

On a simular note... I've saved the keyboard out of a Toshiba 286
luggable
computer... beautiful thing... it even has a keypad on one end...
couldn't
stand to throw it away...

Yeah, this is going to take me forever. I tried, but even getting
started is so difficult that I can't see my way to the end. It's hard
to manage the tester leads, and it's an N^2 operation for each key you
want to test.

Funny story... (not)... While doing what you are trying to do... I looked
through my pile of stuff and found the old motherboard... it had the
connector on it to match the ribbon that comes out of the keyboard... Great
I thought... easier to hook my meter up to and work this out.. I determined
after the last post that it's not impossible as they key order tends to
"line up" so it's sort of predictable what will be the key to go with the
pins...

Anyways, I got my industrial sized heatgun out and heated the backside of
the connector till it came out of the motherboard... worked great...

After it all cooled I connected it up to my ribbon cable and picked up my
keyboard... which had been laying under my motherboard.... which was now a
melted piece of slag.... =( been saving it for years meaning to do
something with it... finally get around to it and wreck it in 2 minutes...

Al...