PDA

View Full Version : AT2XT keyboard converter



Erik
April 8th, 2011, 04:06 PM
The AT2XT keyboard converter (AT2XTKB) project is a Vintage Computer forum (http://www.vintage-computer.com/vcforum/forum.php) driven project to develop and manufacturer a keyboard adapter which allows users to attach AT keyboards to XT class computers. This, for example, allows XT machines to be used on KVM (keyboard/Video/Mouse) switches.

The project is entirely open source, from the design, schematic, layout, bill of materials, and firmware.

http://www.waste.org/~winkles/at2xtfront.jpg

This page will provide links to all the resources utilized in the project.
You can discuss this project here (http://www.vintage-computer.com/vcforum/showthread.php?15907)

The PIC Chip
The heart of the circuitry is a PIC12F629 integrated circuit, referred to as "PIC chip" in other sections of this page.

From the factory, the EEPROM component within the PIC12F629 contains no firmware and therefore needs to be programmed. An EPROM programmer is required to write firmware into the PIC12F629. The custom firmware created for the PIC12F629 in the AT2XTKB is available via a link below, in the 'Downloads' section.

Scancode E0 Pass-Through
In August 2010, it was identified that certain non-US scenarios need to have the E0 scancode passed straight through the AT2XTKB. The VCF discussion on this starts .

After investigation on how to implement that, it was discovered that the AT2XTKB would need to be able to work in one of two modes:
1. Do not pass-through scancode E0; or
2. Pass-through scancode E0.

It was decided to modify the PIC chip's firmware (became version 0.93) and use the then unused jumper, JP1, to select the mode of operation. At that time, the design flaw in regard to jumper JP1 was detected (see 'Jumper JP1' section below).

If you are in the rare situation of needing 'scancode 0xE0 pass-through' functionality on your AT2XTKB, you will need to:
1. Per the 'Jumper JP1' section below, modify your AT2XTKB to cater for the JP1 flaw; then
2. Per the 'Jumper JP1' section below, set jumper JP1 as required.

[h="2"] Jumper JP1
At the design time of the AT2XTKB, jumper JP1 was not used, included for possible future use.
Later, when the PIC code was being changed to cater for 'scancode E0 pass-through' functionality, it was discovered that there was a design flaw in the AT2XTKB that prevented proper jumper use.
The flaw does not affect the vast majority of AT2XTKB users - the AT2XTKB works as expected - there is no need to address the flaw.
For those who need 'scancode E0 pass-through' functionality, the flaw needs to be fixed by adding a pullup resistor, R3, of a value of 47K ohms (actually, anything between 2K and 100K ohms) between pin 1 (Vcc) and pin 4 of the PIC chip.

Jumper settings:

Pullup R3 not present and JP1 on: Normal operation
Pullup R3 not present and JP1 off: Normal operation

Pullup R3 present and JP1 on: Normal operation
Pullup R3 present and JP1 off: Scancode E0 passed through

Downloads
Firmware for PIC Chip (PIC12F629)
Firmware - version 0.94 - Source code (http://www.vintage-computer.com/vcforum/attachment.php?attachmentid=5386&d=1300557151)
Firmware - version 0.94 - HEX file (http://www.vintage-computer.com/vcforum/attachment.php?attachmentid=16553&d=1388197270) (What your EPROM programmer uses.)(Click here (http://www.minuszerodegrees.net/at2xtkb/AT2XTKB_osccal_value.htm) for info about the OSCCAL value.)
PCB/Schematic
Schematic view #1 (http://www.minuszerodegrees.net/at2xtkb/AT2XTKB_wiring_diagram.jpg)
Schematic view #2 (http://www.waste.org/~winkles/AT2XTKBD-sch.pdf) (Resistor R3 not shown.) (Due to a limitation in the drawing software, the arrangement of pins on large DIN connectors is wrong.)
Schematic view #3 (http://www.vintage-computer.com/vcforum/attachment.php?attachmentid=1834&d=1246512592) (Resistor R3 not shown.)
Schematic as an Eagle file (http://www.vintage-computer.com/vcforum/attachment.php?attachmentid=1835&d=1246512746)
PCB board layout (http://www.waste.org/~winkles/AT2XTKBD-brd.pdf) (Seems slightly out of date-there are now mounting holes in the corners.)(Holes for large DIN connectors facing wrong way.)
16553
Bill of Materials
Parts sourced from Digikey Electronics (http://www.digikey.com/)


Qty Digikey # Item
1 AT2XT Keyboard PCB (get this from andrew lynch) or breadboard your own
2 CP-2350-ND CONN DIN 5 PIN FEMALE PCB
1 CP-2260-ND CONN MINI-DIN 6 PIN FEMALE PCB (yes, 6 pin. do not get 5 pin PS/2 connectors!)
1 PIC12F629-I/P-ND IC MCU CMOS FLASH-BASE 8BIT 8DIP
1 A24807-ND CONN IC SOCKET 8POS DIP TIN
1 568-1360-1-ND DIODE SW HS 100V 200MA DO-35
2 P4.7KBACT-ND RES 4.7K OHM CARBON FILM 1/4W 5%
1 P10375TB-ND CAP 47UF 25V ELECT M RADIAL
1 A30916-ND CONN HEADER VERT 2POS .100 TIN (there's a million of these types of headers - not actually req'd)
1 ? 47K ohm resistor (R3) between pin 4 and Vcc. (only needed for jumper to select different operation for non-USA keyboards)
Category:Hardware

1ST1
May 25th, 2016, 12:35 AM
Just for your reference, I have attached the files to another classic computing forum as there is some interest by some users to have this adapter and produce a small series of them. See http://forum.classic-computing.de/index.php?page=Thread&postID=94253#post94253

mac512
May 25th, 2016, 01:49 PM
Is it posible to build this keyboard converter to connect an XT keyboard to an AT computer?

Stone
May 25th, 2016, 01:56 PM
Is it posible to build this keyboard converter to connect an XT keyboard to an AT computer?Why would you want to do that?

XT keyboards generally suck in comparison to AT keyboards and AT keyboards are really plentiful. :-)

Do you happen to have an exceptional XT keyboard that outperforms the AT keyboards in some magnificent manner?

mac512
May 25th, 2016, 06:27 PM
For a long time I've been thinking of replacing my 5155's motherboard with a 286/386 board but I haven't been able to figure out a way to connect the original keyboard...

Vergil
September 4th, 2016, 09:54 PM
For a long time I've been thinking of replacing my 5155's motherboard with a 286/386 board but I haven't been able to figure out a way to connect the original keyboard...

I get exactly what you're saying Mac, did you figure out how to connect to your keyboard yet?

deathshadow
September 4th, 2016, 10:39 PM
Is it posible to build this keyboard converter to connect an XT keyboard to an AT computer?

This guy:
http://www.kbdbabel.org/

Has done several strange keyboards to AT converters, including PC/XT. I agree with @Stone it's not the most useful of directions to my mind, but it has been done. If anything the simpler protocols are easier to read than AT, making such conversion actually simpler to implement than the other direction.

It's one of the sources I've been using for information -- and what led me to question the PC/XT timing info I was seeing as the math on his charts:

http://www.kbdbabel.org/signaling/index.html

... don't seem to add up right, and are inconsistent with how most clocked protocols have a delay to compensate for rise/fall time.

clh333
March 20th, 2017, 08:59 AM
XT keyboards generally suck in comparison to AT keyboards and AT keyboards are really plentiful. :-)

Regarding the AT2XT keyboard PCB: Who is Andrew Lynch and how do I get in touch with him? I recently acquired another 5160 (chassis / cpu only) and want to use an AT keyboard with it.

-CH-

Stone
March 20th, 2017, 09:19 AM
This is he:

http://www.vcfed.org/forum/member.php?3051-lynchaj

gastrodus
June 15th, 2017, 10:24 PM
Hi

Is there a Gerber File available for the AT2XT board?

Regards
Thomas

gekaufman
June 16th, 2017, 05:28 AM
Hi

Is there a Gerber File available for the AT2XT board?

Regards
Thomas

I've been looking for a while, hopefully someone knows where they are...

- Gary

clh333
June 21st, 2017, 02:35 AM
I'm not n expert on the subject but I thought you could generate Gerbers from within Eagle: https://learn.sparkfun.com/tutorials/using-eagle-board-layout/generating-gerbers

-CH-

NobodyIsHere
June 21st, 2017, 08:12 AM
I uploaded the KiCAD file sets, new schematic and PCB layout, and the Gerbers on retrobrewcomputers.org forum

Rodolfo
July 21st, 2017, 12:09 PM
Hi.

I designed a 3D printed custom case for the AT2XT keyboard converter.

Available here: https://www.thingiverse.com/thing:2406022

Enjoy!!

gekaufman
August 10th, 2017, 07:16 PM
Cute case, printed up nicely.

Thanks for making this available.

- Gary


Hi.

I designed a 3D printed custom case for the AT2XT keyboard converter.

Available here: https://www.thingiverse.com/thing:2406022

Enjoy!!

DaCiRo
December 2nd, 2017, 08:18 PM
Hi.

I designed a 3D printed custom case for the AT2XT keyboard converter.

Available here: https://www.thingiverse.com/thing:2406022

Enjoy!!


Putting the pieces together!.
It is simply awesome when all fits in nicely, and this is the case for the fully assembled AT2XT converter. The AT2XT converter product of VCF brightest minds and joined efforts is a simple piece of art. I got the complete assembly unit from Modem7 (soldered like a PRO) and fits like a globe into the Casing design by Rodolfo. The guys at 3DHubs Japan (T's Hub) printed this real fast, from order to delivery it just took 3 days with an outstanding customer service. Many Thanks to all!!!. see pictures below;

I orderer a Clear and White prints,....decided to go with the Clear one,...for now :)


42257

42253422544225542256

rusted_planet
March 31st, 2018, 11:49 AM
Has the hex file for the firmware been removed. I get a dead link while trying to download. Source code too.

Thanks,
Sean

shift838
June 14th, 2018, 02:43 PM
Putting the pieces together!.
It is simply awesome when all fits in nicely, and this is the case for the fully assembled AT2XT converter. The AT2XT converter product of VCF brightest minds and joined efforts is a simple piece of art. I got the complete assembly unit from Modem7 (soldered like a PRO) and fits like a globe into the Casing design by Rodolfo. The guys at 3DHubs Japan (T's Hub) printed this real fast, from order to delivery it just took 3 days with an outstanding customer service. Many Thanks to all!!!. see pictures below;

I orderer a Clear and White prints,....decided to go with the Clear one,...for now :)


42257

42253422544225542256

Where are all the files for this device. I would like to get one made for my vintage PC that uses an XT keyboard. Gerbers, hex, source code and all ???

modem7
June 15th, 2018, 05:30 PM
Has the hex file for the firmware been removed. I get a dead link while trying to download. Source code too.
I did alert the mods to the broken links in the first post, but no repair action effected yet.

The (long) development thread of the AT2TKB is at http://www.vcfed.org/forum/showthread.php?15907
In there, the last production version of the firmware (version 0.94), including source, is published at post #280 (http://www.vcfed.org/forum/showthread.php?15907-AT-to-XT-Keyboard-Converter&p=165336#post165336)

modem7
June 15th, 2018, 06:16 PM
Where are all the files for this device. I would like to get one made for my vintage PC that uses an XT keyboard. Gerbers, hex, source code and all ???
Regarding the "hex, source code", see post #19 above.
I cannot help regarding the rest.
In case it assists you, post #540 (http://www.vcfed.org/forum/showthread.php?15907-AT-to-XT-Keyboard-Converter&p=504647#post504647) of the AT2XTKB development thread indicates that bare PCB's are available at https://oshpark.com/shared_projects/ZFNCQZRX

mdanh2002
June 20th, 2018, 04:59 AM
I tested this AT to XT keyboard converter with Juko ST motherboard and a PS2 keyboard. Almost everything works well, including SHIFT, CAPS LOCK and CTRL keys. However, I have a minor problem. When playing Prince of Persia 1 on this XT using the converter, the SHIFT key is not recognized and I can't take small steps by pressing SHIFT+Arrow key. If I do that, the prince will still take a normal step as if SHIFT wasn't pressed. The SHIFT key works well in the same game (for example, when drinking a potion), in MS-DOS and also in other apps so I am not sure what the issue is.

Does anyone have the same problem?

Stone
June 20th, 2018, 05:03 AM
You might get a more definitive answer by borrowing an XT keyboard.

mdanh2002
June 20th, 2018, 05:11 AM
You might get a more definitive answer by borrowing an XT keyboard.

Nobody around here owns an XT keyboard. The only XT keyboard that I have here has many dead keys and can't really be used. eBay wants at least $100+ for an XT keyboard in unknown condition. I believe the SHIFT key issue is timing-related, e.g. Prince of Persia makes some assumption on timings to detect Shift-Arrow combinations, which work well with an original keyboard but not with the converter.

Stone
June 20th, 2018, 05:39 AM
eBay wants at least $100+ for an XT keyboard in unknown condition.I just looked and there were plenty of XT keyboards under $50. Some were as low as $10.99. These are working keyboards.

mdanh2002
June 20th, 2018, 06:06 AM
I just looked and there were plenty of XT keyboards under $50. Some were as low as $10.99. These are working keyboards.

Well, those don't show up when I search eBay here from Singapore. Maybe those do not ship to Singapore hence they don't show up.

The only thing I find is this, for almost US$100 with shipping to Singapore:

https://www.ebay.com.sg/itm/Vintage-Memorex-Telex-952563-001-XT-AT-Keyboard-Tested-Working/182634639927?hash=item2a85df7237:g:w-kAAOSwaeRZJNcH

Can you post the eBay link?

Stone
June 20th, 2018, 06:50 AM
https://www.ebay.com/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=xt+keyboard&_sacat=0

Alternatively I have some XT keyboards -- but the shipping would be high.

mbbrutman
June 20th, 2018, 07:32 AM
Stone - quit the badgering already.

modem7
June 21st, 2018, 12:31 AM
I tested this AT to XT keyboard converter with Juko ST motherboard and a PS2 keyboard. Almost everything works well, including SHIFT, CAPS LOCK and CTRL keys. However, I have a minor problem. When playing Prince of Persia 1 on this XT using the converter, the SHIFT key is not recognized and I can't take small steps by pressing SHIFT+Arrow key. If I do that, the prince will still take a normal step as if SHIFT wasn't pressed. The SHIFT key works well in the same game (for example, when drinking a potion), in MS-DOS and also in other apps so I am not sure what the issue is.
Does anyone have the same problem?
In post #493 of the AT2XTKB development thread, member schnurzel posted some alternative code for the AT2XTKB.
The link to that post is [here (http://www.vcfed.org/forum/showthread.php?15907-AT-to-XT-Keyboard-Converter&p=370330#post370330)].
In the later posts of #499 and #528, other members reported that the alternative code fixed some issues.
Maybe you should try that code.

mdanh2002
June 21st, 2018, 03:04 AM
In post #493 of the AT2XTKB development thread, member schnurzel posted some alternative code for the AT2XTKB.
The link to that post is [here (http://www.vcfed.org/forum/showthread.php?15907-AT-to-XT-Keyboard-Converter&p=370330#post370330)].
In the later posts of #499 and #528, other members reported that the alternative code fixed some issues.
Maybe you should try that code.

Thanks for the link! Let me try with the updated code ...

sergey
June 26th, 2018, 06:46 AM
Downloads
Firmware for PIC Chip (PIC12F629)
Firmware - version 0.94 - Source code (http://www.vintage-computer.com/vcforum/attachment.php?attachmentid=5386&d=1300557151)
Firmware - version 0.94 - HEX file (http://www.vintage-computer.com/vcforum/attachment.php?attachmentid=16553&d=1388197270)


The links to the firmware above had been broken for a while. @Erik, can you please fix these links or remove them altogether (the firmware is in the XTATKEY_094.zip)?

mdanh2002
June 30th, 2018, 07:05 PM
The links to the firmware above had been broken for a while. @Erik, can you please fix these links or remove them altogether (the firmware is in the XTATKEY_094.zip)?

I believe it's due to improper configuration when the domain was changed from vintage-computer.com to vcfed.org. The correct link should be:

http://www.vcfed.org/forum/attachment.php?attachmentid=5386&d=1300557151
http://www.vcfed.org/forum/attachment.php?attachmentid=5386&d=1300557151

allCAPPS
July 8th, 2018, 08:08 PM
Is anyone making and selling these adapters?

ajacocks
July 8th, 2018, 11:37 PM
Not that I am aware of, but you can order them, yourself, based on the PCB designs that Scott and I have both posted to OSHPark, and then build one, using commonly-available parts. It's not at all a difficult process.

- Alex

Chuck(G)
July 9th, 2018, 07:30 AM
Or you can do what I did for the prototype--just use a hunk of perfboard. It's not a complicated circuit.

gekaufman
July 9th, 2018, 08:44 AM
Is anyone making and selling these adapters?

I have extra pcb's and can easily put one together for you. PM me and we can work out the logistics.

- Gary