PS/2 keyboards

[Jonotallica]

I'm looking around for a used PS/2 keyboard for use with BIOS or older systems.. just to have around in the case that I wish I had one in the future.  The old school mechanical keyboards are really expensive.. and for hobbyists I guess.

 

But there's still the odd PS/2 floating around.. for example Dell, HP, Lenovo.  What I wanted to ask is if these are true PS/2 keyboards, or are they simply USB keyboards with a PS/2 plug attached (sort of like an adapter that's already built in).

 

Some models that I am talking about.. IBM Preferred Pro 89P8300 or HP QY774AA etc.

 

Would an older PC recognize these in the BIOS as being PS/2?  I was reading a bit about certain keyboards that used to come with "dual controller chips" that could auto detect and switch between PS/2 and USB.  But these days, it seems like there's more chance that they'll just be USB?  Regardless of the connector that's attached to the wire?  Are there any known models that can go both ways?  To make things even more frustrating, I'm sure I threw out some keyboards at some point.. not even thinking that maybe one day in the future, I'll wish I held on to one.

[Dr0y]

those are two totally different protocol.  USB work with polling while ps/2 works with interrupt. 

 

 

 

 

[Jonotallica]

I saw videos like that months ago, by memory they talk about performance benefits and drawbacks of each method, from the point of view of gaming and reaction times/latency.

 

Apparently, there's some out there that work with both.. I'll be able to test it out at some point, as I've now purchased one.  A 2006 model but in brand new condition.  But I haven't received all the adapters yet and won't be getting some real world experience for a few weeks/months depending on when everything arrives.  I even have a PS/2 to PCIe adapter coming to ensure future compatibility.  Sometimes these help when installing OS on hardware that wasn't designed for it.

 

Apparently the ones that work with both can use adapters (the small ones) and go back and forth.  They generally are sold as 2 models of the same keyboard.  I could be wrong about that, but it seems this way.  I've seen people speak about this, but have no way to verify it.

 

The ones that aren't able to do that.. (the proper old school PS/2) requires an adapter that also has a converter chip in it.  It's a larger more expensive adapter.  Apparently there are keyboards out there that don't require this converter chip, as the keyboard does it internally.  I'm not sure how.  If I find out more about it in the future, I'll post back about it.  But yeah, the newest USB keyboards are solely USB, so that when they are used with PS/2 adapters.. they don't work on older systems.  It seems they behave as USB regardless of which adapter is used.  It's strange and I don't understand the technical aspects of all of this, but yeah.  They might work within Windows (on a modern system) but won't work outside of Windows, in the BIOS, or on an older OS.

 

There was a period when USB was taking off but PS/2 was still very common.. and that's the era where these "dual compatible" keyboards emerged.  That era ended, which is why the current keyboards are pretty much USB only.  By the way, this 2006 keyboard feels so much better under the fingers than the current ones.. it's a shame when future stuff degrades in quality and gets weaker and flimsier.

 

I'm basing this above mostly off of feedback I read from a lot of online sites over the last 10-15 years.  In terms of user responses after they purchased one for a specific purpose and whether it worked or not.

 

Why does this matter?  There's still people running Windows 98, XP, etc.  Or even just musical or engineering equipment that requires a certain OS, or even just a PS/2 port because USB didn't exist back then.  Then the older one breaks and they need to find a replacement to input into the device.  It's getting harder and harder to find these kind of replacements but they are still out there.  Whether it be a retro genuine PS/2 keyboard (expensive) or a cheaper Logitech, Microsoft, HP, Dell.. etc.  They are getting harder to find but there are still keyboards out there that work.

[Dr0y]

On 5/14/2020 at 12:23 PM, Jonotallica said:

Apparently the ones that work with both can use adapters (the small ones) and go back and forth.  They generally are sold as 2 models of the same keyboard.  I could be wrong about that, but it seems this way.  I've seen people speak about this, but have no way to verify it.

I tried with my old keyboard and it was nightmare in gaming when walking.  The character would stop from time to time and I had to lift and push down the key for it to continue walking.  Obviously my keyboard was too old to be both way and my adapter didn't have a converter chip. 

 

On 5/14/2020 at 12:23 PM, Jonotallica said:

Apparently there are keyboards out there that don't require this converter chip, as the keyboard does it internally.  I'm not sure how.

They probably have the hardware internally to do both at the same time. 

 

 

There are still ps/2 keyboard that are sold brand new but, to my knowledge, they are some generic cheap membrane keyboard.  I was not able to find any one with cherry compatible mechanical switches.