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I want to use my old PS/2 mouse & keyboard with my Dell Latitude, which has no PS/2 ports.

The PS/2 keyboard and mouse I want to connect to my computer, with thumbs up

I am fully aware that the easiest way to do this would to use an active PS/2 to USB converter, like this nice one from Amazon, learning this from reading it here on Tom's hardware forums, here on the Lenovo forums, here on alt windows 10 forums, and even here on Wikipedia.

However, a salesman at an anonymous-remaining electronics company sold me a pair of passive PS/2 to USB adapters, like this not-so nice one from Amazon, which simply changes the pin positions from PS/2 to to USB, but not the data or protocol – which windows 10 doesn't know natively how to make sense of. Sidenote: I don't actually know if that amazon one is a converter or adapter, but it looks similar to what I got.

The PS/2 passive adapters I was sold, with thumbs down

Through both stubbornness not to spend any money, and the fact that it will be a cool project and way to learn how this stuff works, I want to find a way, using software, to interface my laptop and the PS/2 keyboard/mouse using the adapters I bought

Is there a existing way to help Windows interpret the signals the adapted keyboard/ mouse are sending it?
or,
if not, which skills do I need to find a solution, and what is the quickest & easiest way to learn them?

I have a reasonable understanding of Windows, computers, and basic hardware, however my knowledge of drivers, firmware, and what makes Windows work is limited.

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  • Every time we started up we had to unplug and replug to get the keyboard connected to a Windows 10 computer with a PS2 to USB adapter (which I believe is a passive unit) to work. It was plugged into a USB2 port. All I had to do was plug it into one of the computers USB3 ports and the keyboard started up perfectly with the computer afterwards no unplugging and replugging required.
    – Joe Blow
    Commented Nov 25, 2020 at 22:22
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    It is very likely impossible. With a passive adapter, you would need a reverse adapter at the other side and you could make a ps2 cable longer. I doubt if such a thing exists.
    – peterh
    Commented Nov 26, 2020 at 7:43
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    I'm voting to leave this open, despite the fact it's not retro-computing. Many people would like to use their old keyboards, mice, joysticks and trackballs on modern machines, and this would seem to be a legitimate topic for RCSE. The fact that it can't be done isn't the fault of the question!
    – Mark Williams
    Commented Nov 26, 2020 at 9:42
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    An active PS/2 to USB converter dongle is around $10 here in Europe if you look carefully. I've used one with my Model M keyboards for several years.
    – Thorbjørn Ravn Andersen
    Commented Aug 18, 2021 at 6:39

2 Answers 2

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I want to find a way, using software, to interface my laptop and the PS/2 keyboard/mouse using the adapters I bought.

Assuming you want to use the passive PS2-to-USB adapter you just bought to plug it into a USB port on your Windows 10 PC, then this will not work.

The passive PS2-to-USB adapters require the keyboard or mouse to be multi-protocol: The keyboard or mouse must natively speak the USB protocol in addition to the PS2 protocol.

If they do, it will work out of the box. If they don't, then you have the USB host controller in your PC speaking to the PS2 controller in your keyboard and mouse. But you can't reprogram the USB host controller to speak anything else besides the USB protocol, even if you are a crack firmware developer. Because there's no way to reprogram the USB host controller. In the same way, you can't change the PS2 controller in your keyboard or mouse to speak the USB protocol.

So, game over.

If you want a fun project, you will need a piece of hardware that is flexible enough to allow software to control it to such a degree that it can understand the PS2 protocol. So essentially you'll be writing software for an active PS2-to-USB adapter on a RaspPi, a microcontroller, or something similar.

But as you stated in your question, that's not what you want.

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    ...or replace the controller inside the keyboard with something like a Teensy flashed with DIY keyboard controller firmware... again, just as a fun project. It's going to be more expensive and time-consuming than a mass-produced active converter.
    – ssokolow
    Commented Nov 27, 2020 at 20:55
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It's possible that the mouse and keyboard implement both PS/2 and USB; on these devices, the passive connectors work. However, if this is not the case, you won't be able to use the PS/2 device over USB, since the device will not be sending coherent data to the USB controller.

It is theoretically possible, however, for you to wire the data and clock lines of the PS/2 device to input lines in your PC's parallel port interface (if it has one), and then write a Windows kernel driver to interpret the data. However, if you're going as far as to implement an active converter in software on your machine, it's probably easier to buy a pre-built USB-to-PS/2 active converter.

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  • I believe the mouse and keyboard were developed before USB interfaces were even in vogue. In any case, they're definitely not outputting both PS/2 signals & USB. My latitude doesn't have a parallel port, and even if it did, I'd have to buy/manufacture a usb to parallel port converter - which defeats the point of not buying a converter. I was envisioning simply writing a "Windows kernel driver" (or the like) that takes the incoherent PS/2 data from the USB port and interprets it into mouse movement and keyboard strokes.
    – Aaroncfj
    Commented Jul 6, 2019 at 11:43
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    @Aaroncfj Unfortunately, the CPU will never even see the mouse and keyboard's signals; USB doesn't tolerate nonsense.
    – wizzwizz4 ♦
    Commented Jul 6, 2019 at 11:58
  • DEC LK201 keyboards can be used in this way, because it's protocol is serial, though power is an issue. Linux has a device driver which allows a keyboard connected thru the serial port to be a console keyboard.
    – Stefan Skoglund
    Commented Jan 10, 2021 at 20:10
  • @StefanSkoglund an RS232 serial port is a very different animal than a USB port - especially if it is a true PCI/LPC connected RS232 port, which does allow a kernel driver access to the raw signals....
    – rackandboneman
    Commented Aug 27, 2022 at 14:19

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