The adapter is passive. At and ps/2 are the same, just different plug.

Sphere478 wrote on 2023-08-14, 06:14:

The adapter is passive. At and ps/2 are the same, just different plug.

Ok but does it possible that newmade ps/2 keyboards have native usb interface with convertor to ps/2 which gives incompatibility issues . I found new ps/2 keyboard and it's usb one with adapter to ps/2

ciornyi wrote on 2023-08-14, 06:48:

Sphere478 wrote on 2023-08-14, 06:14:

The adapter is passive. At and ps/2 are the same, just different plug.

Ok but does it possible that newmade ps/2 keyboards have native usb interface with convertor to ps/2 which gives incompatibility issues . I found new ps/2 keyboard and it's usb one with adapter to ps/2

Where does one get newly made PS/2 keyboards these days ?

Typically, USB keyboards with PS/2 compatibility came with a passive adapter. When this adapter is used, the keyboard's micro-controller switches to PS/2 mode . Those passive adapters came in different pinouts (I believe, from memory, that Logitech and Microsoft each had their own adapter pinout and they were not interchangeable. There may have been other pinouts). I have not heard of compatibility being a problem with those keyboards at the time, but maybe there were issues that I have not heard about.

As for newly made PS/2 keyboards (are you sure they are not new-old-stock ?), I have no idea what issues they may have, if any.

Maybe it would help if you could tell us exactly which keyboard(s) and motherboards you are using and a photograph of the adapter(s).

As a rule AT and PS/2 are electrically identical. USB is completely different.

To connect a USB keyboard to an AT or PS/2 motherboard requires an active adapter. There was a small number of keyboards around the turn of the millennium that supported both AT/PS/2 and USB protocols and could use a passive USB->PS/2 adapter, but 1) they were only made for a short period and 2) there is no standard for that adapter pinout so you would need one specific to you keyboard. Note that active adapters only support basic USB HID functonality and may have trouble with complicated keyboards that do more. Finally not all active adapters work equally well. I've bought three different types on AliExpress. Two work without issue, the third is detected as USB device but does not function as a keyboard.

My best guess based on the info so far is that you have a USB keyboard and a passive USB-PS/2 adapter, and the USB keyboard does not support PS/2 protocol and/or the adapter's pinout does not match what the keyboard needs.

As an aside, XT and AT keyboards have the same DIN connector but different protocols, so not everything with that DIN-5 connector is equal. Some early AT keyboards have XT/AT switches to configure which protocol they use. Another reason to be absolutely sure of what you are using.

darry wrote on 2023-08-14, 07:01:

Where does one get newly made PS/2 keyboards these days ?

Unicomp (as in the company that still makes IBM model M keyboards) still makes them.

In not-ancient history but at least 2010s ,it seemed gamers preferred PS/2 keyboards and this was why many desktop boards kept a single PS/2 combo port even if they dropped the mouse port. Has that passed by now?

> Has that passed by now?

My go-to site for modern parts currently lists 101 AM5 mainboards, and 29 of those are tagged as having a PS/2 port. So my answer would be "not quite, but we're getting there".

dionb wrote on 2023-08-14, 07:12:

Maybe it would help if you could tell us exactly which keyboard(s) and motherboards you are using and a photograph of the adapte […]
Show full quote

Maybe it would help if you could tell us exactly which keyboard(s) and motherboards you are using and a photograph of the adapter(s).

As a rule AT and PS/2 are electrically identical. USB is completely different.

To connect a USB keyboard to an AT or PS/2 motherboard requires an active adapter. There was a small number of keyboards around the turn of the millennium that supported both AT/PS/2 and USB protocols and could use a passive USB->PS/2 adapter, but 1) they were only made for a short period and 2) there is no standard for that adapter pinout so you would need one specific to you keyboard. Note that active adapters only support basic USB HID functonality and may have trouble with complicated keyboards that do more. Finally not all active adapters work equally well. I've bought three different types on AliExpress. Two work without issue, the third is detected as USB device but does not function as a keyboard.

My best guess based on the info so far is that you have a USB keyboard and a passive USB-PS/2 adapter, and the USB keyboard does not support PS/2 protocol and/or the adapter's pinout does not match what the keyboard needs.

As an aside, XT and AT keyboards have the same DIN connector but different protocols, so not everything with that DIN-5 connector is equal. Some early AT keyboards have XT/AT switches to configure which protocol they use. Another reason to be absolutely sure of what you are using.

Hey sorry for confusing , english isnt my native . Keyboard is Genius ps/2 and it worked before i tested it on Azza pt 5it v2.x with ps/2 to AT adapter. Those boards doesnt work normally so i created 3x Azza PT-5IT V2.x semi dead ? thread as i thought it has dead AT port or keyboard . After awhile i got bunch of hardware so i decided to test it with genius keybord and realized its dead . So since keyboard doesnt work on many systems its dead i guess . That make me qurious if there is something between those standarts that cause this issue.

jakethompson1 wrote on 2023-08-14, 08:01:

darry wrote on 2023-08-14, 07:01:

Where does one get newly made PS/2 keyboards these days ?

Unicomp (as in the company that still makes IBM model M keyboards) still makes them.

In not-ancient history but at least 2010s ,it seemed gamers preferred PS/2 keyboards and this was why many desktop boards kept a single PS/2 combo port even if they dropped the mouse port. Has that passed by now?

I forgot about Unicomp, TY . There are likely others (probably mostly niche ones, possibly for industrial applications). I will have to check for curiosity's sake.

elszgensa wrote on 2023-08-14, 08:56:

> Has that passed by now?

My go-to site for modern parts currently lists 101 AM5 mainboards, and 29 of those are tagged as having a PS/2 port. So my answer would be "not quite, but we're getting there".

One reason for the PS/2 port still being there is likely, I would guess, because there are institutional, commercial and/or industrial setups (including KVMs) that have large numbers of workstations set up with PS/2 keyboards (and possibly a bazillion spare keyboards). I wonder if I am right about that and what other reasons might explain this.

ciornyi wrote on 2023-08-14, 16:23:

dionb wrote on 2023-08-14, 07:12:

Maybe it would help if you could tell us exactly which keyboard(s) and motherboards you are using and a photograph of the adapte […]
Show full quote

Maybe it would help if you could tell us exactly which keyboard(s) and motherboards you are using and a photograph of the adapter(s).

As a rule AT and PS/2 are electrically identical. USB is completely different.

To connect a USB keyboard to an AT or PS/2 motherboard requires an active adapter. There was a small number of keyboards around the turn of the millennium that supported both AT/PS/2 and USB protocols and could use a passive USB->PS/2 adapter, but 1) they were only made for a short period and 2) there is no standard for that adapter pinout so you would need one specific to you keyboard. Note that active adapters only support basic USB HID functonality and may have trouble with complicated keyboards that do more. Finally not all active adapters work equally well. I've bought three different types on AliExpress. Two work without issue, the third is detected as USB device but does not function as a keyboard.

My best guess based on the info so far is that you have a USB keyboard and a passive USB-PS/2 adapter, and the USB keyboard does not support PS/2 protocol and/or the adapter's pinout does not match what the keyboard needs.

As an aside, XT and AT keyboards have the same DIN connector but different protocols, so not everything with that DIN-5 connector is equal. Some early AT keyboards have XT/AT switches to configure which protocol they use. Another reason to be absolutely sure of what you are using.

Hey sorry for confusing , english isnt my native . Keyboard is Genius ps/2 and it worked before i tested it on Azza pt 5it v2.x with ps/2 to AT adapter. Those boards doesnt work normally so i created 3x Azza PT-5IT V2.x semi dead ? thread as i thought it has dead AT port or keyboard . After awhile i got bunch of hardware so i decided to test it with genius keybord and realized its dead . So since keyboard doesnt work on many systems its dead i guess . That make me qurious if there is something between those standarts that cause this issue.

Does that Genius brand keyboard have a switch to configure it for AT and PS/2 use OR for XT use ?

darry wrote on 2023-08-14, 17:07:

ciornyi wrote on 2023-08-14, 16:23:

dionb wrote on 2023-08-14, 07:12:

Maybe it would help if you could tell us exactly which keyboard(s) and motherboards you are using and a photograph of the adapte […]
Show full quote

Maybe it would help if you could tell us exactly which keyboard(s) and motherboards you are using and a photograph of the adapter(s).

As a rule AT and PS/2 are electrically identical. USB is completely different.

To connect a USB keyboard to an AT or PS/2 motherboard requires an active adapter. There was a small number of keyboards around the turn of the millennium that supported both AT/PS/2 and USB protocols and could use a passive USB->PS/2 adapter, but 1) they were only made for a short period and 2) there is no standard for that adapter pinout so you would need one specific to you keyboard. Note that active adapters only support basic USB HID functonality and may have trouble with complicated keyboards that do more. Finally not all active adapters work equally well. I've bought three different types on AliExpress. Two work without issue, the third is detected as USB device but does not function as a keyboard.

My best guess based on the info so far is that you have a USB keyboard and a passive USB-PS/2 adapter, and the USB keyboard does not support PS/2 protocol and/or the adapter's pinout does not match what the keyboard needs.

As an aside, XT and AT keyboards have the same DIN connector but different protocols, so not everything with that DIN-5 connector is equal. Some early AT keyboards have XT/AT switches to configure which protocol they use. Another reason to be absolutely sure of what you are using.

Hey sorry for confusing , english isnt my native . Keyboard is Genius ps/2 and it worked before i tested it on Azza pt 5it v2.x with ps/2 to AT adapter. Those boards doesnt work normally so i created 3x Azza PT-5IT V2.x semi dead ? thread as i thought it has dead AT port or keyboard . After awhile i got bunch of hardware so i decided to test it with genius keybord and realized its dead . So since keyboard doesnt work on many systems its dead i guess . That make me qurious if there is something between those standarts that cause this issue.

Does that Genius brand keyboard have a switch to configure it for AT and PS/2 use OR for XT use ?

Nope it was cheap ps/2 keyboard i bought in 2014-2016

There is also this .

https://www.digikey.com/en/products/detail/tr … DT60002/4438088

137 $US

From the dataheet :

1Description
2Preserve Your IT investments
3Keep your PS/2 legacy equipment! The PS/2 to USB Converter, a small, plug & play converter, transforms
4PS/2 equipment from outdated devices to valuable tools for today's data centers.
5Rather than advocate "rip and replace" IT solutions, this adapter preserves past investments by
6repurposing and updating existing IT equipment. Once you have gone through the hassle of setting up a
7KVM switch, for example, it is inconvenient and expensive to throw it out and start from scratch. With the
8PS/2 to USB Converter, your life at the rack only gets easier: you can now use your KVM switch with a
9new generation USB keyboard and mouse. With your PS/2 KVM switches, you can still extend the life of
10the IT equipment that you already bought.
11Flexible USB Support
12With the PS/2 to USB Converter, you can use your PS/2 device (KVM switches, KVM extenders, and
13servers) with a USB keyboard and mouse.
14Unlike other converters, the PS/2 to USB Converter accommodates multiple permutations of keyboard
15and mice combinations:
16● Supports USB keyboard with USB mouse
17● Supports USB keyboard with PS/2 mouse
18● Supports USB mouse with PS/2 keyboard
19Features
20● Compatible with PS/2 servers / KVM switches / KVM extenders
21● Pure hardware solution - no software/network conflicts
22● No need for external power
23● Compact size
24● Plug & play
25● Compliant with the Federal Trade Agreements Act (TAA) for GSA Schedule purchases

Here is something that sometimes (often) comes up. You haven’t mentioned this but it is related.

The mouse connector on many ss7 and earlier mobos were often proprietary pin header pinouts leading to people miswiring them all the time. Sometimes this can fry stuff and as you know, they are the same physical connector as ps/2

Anyway, usb and ps/2 basically have four wires. Gnd, data-, data+, and 5v for usb
and
gnd, clock, data, and 5v for ps/2

They were similar which is why they were able to make keyboard chips that could work with both. I kinda doubt that if it was hooked up correctly that you would fry a usb device on a ps2 adapter or a ps/2 port on a usb only device on adapter. Again, not the same as others have said, but close enough that electronic wizardry could bridge the gap.