Maker Pro
Maker Pro

Convert USB keyboard to PS2?

TTL

Oct 24, 2013
195
Joined
Oct 24, 2013
Messages
195
Is it possible to convert a USB keyboard to PS/2?
I'd like to use an Apple USB keyboard with an old computer having only ancient PS/2 ports.

If there's no easy way to convert the USB signal, perhaps I could open up the keyboard and replace the USB electronics with a PS/2 interface board taken from a PS/2 keyboard? Is the actual mechanical keyboard wiring matrix usually standard in a keyboard?
 

TTL

Oct 24, 2013
195
Joined
Oct 24, 2013
Messages
195
From reading the comments section at that Amazon link it simply provides the mechanical/electrical connection between USB and PS/2 while the actual compatibility usually only works with older USB keyboards and not current ones. I doubt it'll work with my keyboard but being so cheap I might as well just give it a go.

But how about the question I had concerning using the keyboard wiring matrix with a genuine PS/2 interface board? Does the wiring matrix usually follow a standard?
 

shumifan50

Jan 16, 2014
579
Joined
Jan 16, 2014
Messages
579
Why do you want to contaminate any device with Apple peripherals?
If you spend half the money an Apple keyboard costs, you can get at least 4 times the quality.
I actually prefer Logitech keyboards.

As far as matrix mapping is concerned I would be surprised if Apple uses the same matrix as anybody else as they make a point of making their peripherals in such a way as to only allow replacement by another Apple component. If it was one of the generic keyboards, you might have had a better chance.
 

TTL

Oct 24, 2013
195
Joined
Oct 24, 2013
Messages
195
An Apple hater? ;)
So, Apple aside and looking at other brands; is the keyboard wiring matrix standard?
I see Logitech have some nice keyboards, but the question again is if they will work with a PS/2 port. I dug this out of Wikipedia on the subject of PS/2:

Conversion between PS/2 and USB
Many keyboards and mice were specifically designed to support both the USB and the PS/2 interfaces and protocols, selecting the appropriate connection type at power-on. Such devices are generally equipped with a USB connector and ship with a passive wiring adapter to allow connection to a PS/2 port. Such passive adapters are not standardized and may therefore be specific to the device they came with. They cannot be used to adapt other devices to PS/2 ports.[citation needed] While combi-devices supporting USB and PS/2 are still available, most USB keyboards and mice in the 2010s no longer come with or even support the PS/2 protocol.[citation needed] Connecting them to a PS/2 port would require an adapter, actively translating between the protocols. Such adapters only support certain classes of USB devices such as keyboards and mice, but are not model- or vendor-specific.

Older PS/2-only peripherals can be connected to a USB port via an active adapter, which generally provides a pair of PS/2 ports at the cost of one USB port.


So it seems the USB to PS/2 adapter plug solution suggested earlier isn't standardized (colored in red above, by me). And with USB keyboards made after 2010 they likely don't contain the combined USB and PS/2 protocol information either.
But what's the deal about the active adapters (colored in green by me, above)? I tried to find some more information and came across the StarTech USB mouse/keyboard adapter at Amazon for a hefty US$ 82. Apparently it's not the silver bullet I was hoping for, based on one of the reviews. Other active adapters I found were the other way round (allowing PS/2 mice and keyboards to be used with modern USB-equipped computers).
 

shumifan50

Jan 16, 2014
579
Joined
Jan 16, 2014
Messages
579
I don't know about Windows, but in Linux the mapping can be set up on the PC in Linux and you can define any key to be any 'character'. So the matrix is not that important as you just take the code you get and set it up to be the code you want.
To be honest - I think it will be much less bother (and cost) to just get an appropriate keyboard. As it is you will have to gut an existing keyboard to get the interface board.
 

TTL

Oct 24, 2013
195
Joined
Oct 24, 2013
Messages
195
I do in fact have a working PS/2 keyboard which I could take the guts out from but I agree that I might be better off just getting an appropriate keyboard. Unfortunately there's very little to choose from when it comes to PS/2. They're all huge and bulky. I'd like something compact and slim (yet still a full extended keyboard with a numeric keypad etc.).
 
Top