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Thread: AT to XT Keyboard Converter

  1. #1
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    Default AT to XT Keyboard Converter

    I want to know if anyone has ever designed a converter box that will make an AT keyboard, like the most of the IBM Model Ms and other more modern 101 and 104 keyboards, work properly in a PC/XT that expect an 83-key keyboard or need a keyboard with an XT/AT switch. I have heard of boxes that will let an XT keyboard work in a modern system that expects an AT keyboard, but has the reverse been done?

  2. #2
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    If it hasn't, drop me a line. I've probably got enough code to put something together in a uC.

  3. #3
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    wiki page is here with all the details distilled from this thread:
    http://wiki.vintage-computer.com/ind...oard_converter


    I too would be interested in such a device.
    I would like to use my PC/XT machines on a KVM switch with my 286+ machines.

    sounds like we may have another VC forum project on our hands! Go chuck go!
    Last edited by hargle; May 18th, 2010 at 07:12 PM.

  4. #4
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    There has certainly been a box to do the opposite, and they go for about $100 if you can find a custom one online.. Perhaps they work in either direction?

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    I'll put this one on my to-do list, unless someone beats me to it.

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    If you feel like building custom ones for XT-to-AT I'd buy one.. Hopefully not at $100 tho :P

  7. #7

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    i'd like one of these boxes too. i have one of my 8088s on a KVM switch but it's a pain because i have to keep a separate keyboard sitting on top of the tower and make room for it on my desk when i switch to it.

    making a converter would be pretty trivial with a very very low powered single board computer, 2 serial ports, and a little bit of ROM code.

    read the tech details of the XT keyboard protocol here:

    http://www.cs.cmu.edu/~jmcm/info/key2.txt



    tech details of the AT/PS2 protocol:

    http://www.beyondlogic.org/keyboard/keybrd.htm




    a possible cheap-o solution would be wiring an AT style keyboard into one of the 8088's serial ports and using a specially designed TSR to interpret and move the data into the computer's keyboard buffer, but i'm not sure if that would work for all software or not.
    Last edited by Mike Chambers; June 3rd, 2009 at 07:23 PM.
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  8. #8
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    Quote Originally Posted by Mike Chambers View Post
    making a converter would be pretty trivial with a very very low powered single board computer, 2 serial ports, and a little bit of ROM code.
    With a decent small uC, you probably don't even need the serial ports--just bit-bang it.

    And, in fact, most uC UARTS can't be used--while the keyboard sends a start bit, it sends the remainder of the data in clocked synchronous mode--and uses an 11-bit (start+8 data+parity+stop) format. Most UARTs can't handle 8bits+parity.

    I'm first going to see if it'll fit in a PIC 12F629. That'd be very slick. Otherwise, I can use an ATMega8.
    Last edited by Chuck(G); June 3rd, 2009 at 09:24 PM.

  9. Default Check this link

    I will get one for me too.
    http://www.clickykeyboards.com/index.cfm/fa/items.main/parentcat/11066/subcatid/0/id/176955


    http://www.cs.cmu.edu/~jmcm/info/key2.txt

    My apex 8088 xt take at keyboard if it is use full i will upload the BIOS.
    Last edited by nesan; June 7th, 2009 at 09:09 AM.

  10. #10
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    I just assembled the prototype in an old "Monitor Miser" box. It's scarcely anything--an 8 pin 12F629, a capacitor and a couple of resistors. (The LED is for debugging).

    Given the right components (i.e. SMT), one could probably fit it inside a 5-pin DIN connector shell.

    I'll be working on the code this week--I've already constructed the translation tables.

    All in all, this looks like it will be very easy.

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