[SOLVED] Getting an old keyboard to work thru USB

[excitron]

Hi folks, I have an old Fujisu keyboard from the 90s (unfortunately I covered the back with a large rubber plate, so the model number is buried) that I want to use through USB. It has the larger PS2 (PS?) plug. When I try to use it through a standard PS2-to-USB adapter (via a large-to-small PS2 adapter) the system doesn't see the keyboard. I don't know anything about their standards, but I suspect these older keyboards may work with either different voltage and/or com protocols. I suspect I may need some kind of active adapter for it.

I'm curious if there is an adapter I can use out there that will allow me to use this keyboard via USB. Any info is greatly appreciated, thanks.

 

[Lutfij]

Well, first off, we're going to need to know the model of the keyboard so we're sure you're referring to the right port. Also, in today's age of computing your motherboard should have a PS/2 keyboard port. If you're dealing with an MSI board(of the 4th gen for Intel's processors), the port should be compatible with either a PS/2 mouse or a PS/2 keyboard.

You don't need an active adapter, that kind of thing is only necessary for display adapters.

Mind sharing the specs of the build that you're trying to hook the keyboard to? List them like so:
CPU:
Motherboard:
Ram:
SSD/HDD:
GPU:
PSU:
Chassis:
OS:

 

[SkyNetRising]

Keyboard from 90s - it probably has AT(din5) connector.

 

[excitron]

Keyboard from 90s - it probably has AT(din5) connector.

Yes, that's it. I wasn't sure of the plug type name, but it's an AT plug. I managed to pull the rubber backing off without destroying it. The keyboard is part of the Fujitsu FKB4700 series, model FKB4720-601, rated 5Vdc@250mA.

I have an AT-PS2 adapter on it and have been using it for years on an old Cybex Switchview 4-port KVM without problem, but when I plug the AT-PS2 adapter into a PS2-USB adapter, the computer doesn't recognize the keyboard. This has happened with 3 different machines. I've now done a search online for AT-USB adapters, and the only hits I get is for this at eBay, and this, which won't serve my perposes because it doesn't have the proper female USB jack, and frankly looks rather crude and fragile just laying there exposed like that.

So would the eBay adapter work, or do I need an active circuit like the second unit with a proper female USB jack?

Thanks again.

 

[lordmogul]

Depends.
Keyboards using the DIN port come in 3 different protocols.
The latest one (PC/AT) is basically identical to PS/2 in all but the plug.
If that keyboard is of this type than any adapter that accepts PS/2 should also work, it would even be possible to simply solder a PS/2 port to the keyboard.

For the earlier ones (PC and PC/XT) it most likely requires some active adapter, as any modern system would probably be not able to run a protocol that hasn't been used since the 80's