Convert USB keyboard to PS/2 or AT?

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Convert USB keyboard to PS/2 or AT?

Postby cyclone3d » 2017-12-14 @ 16:30

Currently I only have 1 keyboard that will work on AT systems via a PS/2 to AT adapter despite having a number of different PS/2 keyboards.

I would very much like to be able to use a newer USB mechanical keyboard on computers with PS/2 or AT ports.

Does anybody know of any such converter? I was unable to find any.

I did find a project to make a converter to be able to use AT and PS/2 keyboards through USB but that doesn't help me one bit.

Should I just bite the bullet and get a mechanical AT keyboard?
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Re: Convert USB keyboard to PS/2 or AT?

Postby skitters » 2017-12-14 @ 17:08

cyclone3d wrote:Should I just bite the bullet and get a mechanical AT keyboard?

In my opinion -- Yes.
It's just easier to have a real AT keyboard.
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Re: Convert USB keyboard to PS/2 or AT?

Postby xjas » 2017-12-14 @ 17:16

If the USB keyboard supports PS/2 through one of those "dumb" (no circuitry) adapters, you can just hack off the USB plug and solder on an AT one.
selected (probably) unfinished build threads { The Hipster Way | Only One 'T' | In a Lunchbox | World's Ugliest Keyboard | IT IS THE NINETIES }
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Re: Convert USB keyboard to PS/2 or AT?

Postby cyclone3d » 2017-12-14 @ 17:19

skitters wrote:
cyclone3d wrote:Should I just bite the bullet and get a mechanical AT keyboard?

In my opinion -- Yes.
It's just easier to have a real AT keyboard.


Easier yes.. but what happens when the supply of good old keyboards dries up?

In any case, I ended up ordering a Laser III XT/AT keyboard with the SMK white switches.
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Re: Convert USB keyboard to PS/2 or AT?

Postby cyclone3d » 2017-12-14 @ 17:23

xjas wrote:If the USB keyboard supports PS/2 through one of those "dumb" (no circuitry) adapters, you can just hack off the USB plug and solder on an AT one.


If that were the case, why couldn't I just use a USB-PS/2 and then a PS/2-AT adapter?

And even if that were the case, would it for sure work with an AT adapter? Like I said before, I have a number of PS/2 keyboards, but only a single one that actually works with an AT adapter.
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Re: Convert USB keyboard to PS/2 or AT?

Postby c0keb0ttle » 2017-12-14 @ 22:04

I use a cheap ass standard USB office keyboard through normal USB/ps2 and ps2/at adapters and it works fine.
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Re: Convert USB keyboard to PS/2 or AT?

Postby cyclone3d » 2017-12-14 @ 22:32

c0keb0ttle wrote:I use a cheap ass standard USB office keyboard through normal USB/ps2 and ps2/at adapters and it works fine.


That keyboard must specifically support PS/2 signaling then.

What keyboard is it?
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Re: Convert USB keyboard to PS/2 or AT?

Postby xjas » 2017-12-15 @ 00:04

cyclone3d wrote:
xjas wrote:If the USB keyboard supports PS/2 through one of those "dumb" (no circuitry) adapters, you can just hack off the USB plug and solder on an AT one.


If that were the case, why couldn't I just use a USB-PS/2 and then a PS/2-AT adapter?

And even if that were the case, would it for sure work with an AT adapter? Like I said before, I have a number of PS/2 keyboards, but only a single one that actually works with an AT adapter.


PS/2 signalling is electrically identical to AT, the only thing the adapter does is re-route the pins. In this case I'd suspect the adapter is at fault (broken contacts, etc.)

You absolutely 100% can cut a USB connector off a USB/PS/2 hybrid keyboard and solder on an AT connector - I've done it - provided the keyboard fully supports PS/2 through the use of a dumb adapter. If it needs any "smart conversion" it won't work.
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Re: Convert USB keyboard to PS/2 or AT?

Postby cyclone3d » 2017-12-15 @ 00:38

I was using the same brand new converter when I tested all my ps2 keyboards. Maybe the board d I was testing with is just really picky. I know the other keyboards work with a computer that has ps2 ports.
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Re: Convert USB keyboard to PS/2 or AT?

Postby Azarien » 2017-12-15 @ 07:47

cyclone3d wrote:
skitters wrote:
cyclone3d wrote:but what happens when the supply of good old keyboards dries up?


If a real need comes up, someone will solve the problem and start selling custom-made adapters on this forum :-)
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Re: Convert USB keyboard to PS/2 or AT?

Postby .legaCy » 2017-12-16 @ 17:50

Isn't the PS/2 to AT adapter just a "connector size/pinout" adapter ? like those CF to IDE Adapter
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Re: Convert USB keyboard to PS/2 or AT?

Postby kaputnik » 2017-12-16 @ 18:13

cyclone3d wrote:
xjas wrote:If the USB keyboard supports PS/2 through one of those "dumb" (no circuitry) adapters, you can just hack off the USB plug and solder on an AT one.


If that were the case, why couldn't I just use a USB-PS/2 and then a PS/2-AT adapter?

And even if that were the case, would it for sure work with an AT adapter? Like I said before, I have a number of PS/2 keyboards, but only a single one that actually works with an AT adapter.


Using an old Blackbox KVM switch with my retro rigs, that just won't accept dual protocol keyboards, only pure PS/2 ones works. Perhaps a related problem? Thought of completely disabling USB signalling in the keyboard controller, hoping it could be done with some simple hardware hack, like pulling down a pin or something. Turned out the only way to do it was by firmware hacking, which is outside my skill set, so couldn't try it.

.legaCy wrote:Isn't the PS/2 to AT adapter just a "connector size/pinout" adapter ? like those CF to IDE Adapter


Yes it is :)
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Re: Convert USB keyboard to PS/2 or AT?

Postby .legaCy » 2017-12-16 @ 18:32

kaputnik wrote:
cyclone3d wrote:
xjas wrote:If the USB keyboard supports PS/2 through one of those "dumb" (no circuitry) adapters, you can just hack off the USB plug and solder on an AT one.


If that were the case, why couldn't I just use a USB-PS/2 and then a PS/2-AT adapter?

And even if that were the case, would it for sure work with an AT adapter? Like I said before, I have a number of PS/2 keyboards, but only a single one that actually works with an AT adapter.


Using an old Blackbox KVM switch with my retro rigs, that just won't accept dual protocol keyboards, only pure PS/2 ones works. Perhaps a related problem? Thought of completely disabling USB signalling in the keyboard controller, hoping it could be done with some simple hardware hack, like pulling down a pin or something. Turned out the only way to do it was by firmware hacking, which is outside my skill set, so couldn't try it.

.legaCy wrote:Isn't the PS/2 to AT adapter just a "connector size/pinout" adapter ? like those CF to IDE Adapter


Yes it is :)

So it shouldn't be a problem the end of good AT keyboards supply.
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Re: Convert USB keyboard to PS/2 or AT?

Postby Samir » 2017-12-16 @ 19:18

If you have plenty of ps2 keyboards, a simple ps2 to AT cable will be your best bet. And keep in mind that some keyboards won't like certain motherboards--these were just conflicts we would run across back in the day. :cool:
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Re: Convert USB keyboard to PS/2 or AT?

Postby p24t » 2017-12-16 @ 19:36

I feel fairly confident saying there are no good active converters out there. Much easier to just buy a keyboard that supports PS/2 signaling. I've found that the Filco Majestouch 2 and WASD CODE keyboards make for nice ps/2 compatible mechanicals.
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Re: Convert USB keyboard to PS/2 or AT?

Postby Samir » 2017-12-18 @ 05:24

p24t wrote:I feel fairly confident saying there are no good active converters out there.
Why would you need an active converter for px2 to AT? There's only a connector difference, nothing more. :confused:
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Re: Convert USB keyboard to PS/2 or AT?

Postby Plasma » 2017-12-18 @ 05:32

p24t wrote:I feel fairly confident saying there are no good active converters out there. Much easier to just buy a keyboard that supports PS/2 signaling. I've found that the Filco Majestouch 2 and WASD CODE keyboards make for nice ps/2 compatible mechanicals.


I disagree. I have a couple NTI converters (USB-PS2-R) that work great. They are picky about mice (won't work with my KVM's emulated mouse), but all keyboards I tried including my KVM work fine.

There is a guy selling them on ebay for $10 which is a steal considering they are normally $70+.
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Re: Convert USB keyboard to PS/2 or AT?

Postby cyclone3d » 2017-12-18 @ 06:37

Plasma wrote:
p24t wrote:I feel fairly confident saying there are no good active converters out there. Much easier to just buy a keyboard that supports PS/2 signaling. I've found that the Filco Majestouch 2 and WASD CODE keyboards make for nice ps/2 compatible mechanicals.


I disagree. I have a couple NTI converters (USB-PS2-R) that work great. They are picky about mice (won't work with my KVM's emulated mouse), but all keyboards I tried including my KVM work fine.

There is a guy selling them on ebay for $10 which is a steal considering they are normally $70+.


You, sir, have won the Internets for the day.

I did a lookup for prices elsewhere and I was only coming up with them in the $120 range.

I have now ordered 2 of them from that eBay seller.
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Re: Convert USB keyboard to PS/2 or AT?

Postby p24t » 2017-12-22 @ 12:11

Plasma wrote:
p24t wrote:I feel fairly confident saying there are no good active converters out there. Much easier to just buy a keyboard that supports PS/2 signaling. I've found that the Filco Majestouch 2 and WASD CODE keyboards make for nice ps/2 compatible mechanicals.


I disagree. I have a couple NTI converters (USB-PS2-R) that work great. They are picky about mice (won't work with my KVM's emulated mouse), but all keyboards I tried including my KVM work fine.

There is a guy selling them on ebay for $10 which is a steal considering they are normally $70+.


Interesting. Last time I tried any active conversion from usb to ps/2, I got noticeable lag and even dropped keystrokes if I recall.
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Re: Convert USB keyboard to PS/2 or AT?

Postby cyclone3d » 2017-12-22 @ 15:17

Just an update. I received these the other day and they are brand new in original box.

I'll post another update when I test.
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