Looking to connect a usb mouse to an old AT. - Page 1
Forum section: electronics / general

author: avitsur
author_rank: Contributor
timestamp: June 12, 2025, 06:26:02 am
content: I have an old pc based on a TM-486SPS board. I want to run it. in order to do so, I have to connect a keyboard and a mouse. the keyboard issue is simpler because there are adapters that enable to connect a usb keyboard to it. bigger problem is the need to connect a mouse to it's 9 pin d type com port. I would like to ask if it's possible to make an adapter (I wasn't able to find one) that consists of a 9 pin female d type connector to a female usb connector - of course the wiring diagram of it, if it's possible at all, the compatibility of a usb mouse to the com port.

author: Kean
author_rank: Unknown
timestamp: June 12, 2025, 08:41:39 am
content: While you can get converters between PS2 and a USB mouse (and vice-versa), I don't think I've ever seen anything to adapt a USB mouse to a serial mouse. I can't imagine there would be much demand.There is some discussion on another site with a PCB design for conversion using a Raspberry Pi.https://www.vogons.org/viewtopic.php?t=76976A whole Linux computer (even if only using a tiny RPi Zero) seems like overkill. But the discussion links to some other potential solutions.If you search eBay or similar, I am sure you could find a second hand mouse with serial connector.

author: pcprogrammer
author_rank: Super Contributor
timestamp: June 12, 2025, 09:26:15 am
content: Quote from: Kean on June 12, 2025, 08:41:39 amThe problem is that you need USB host capability to do this. On a Raspberry PI running Linux this is easily available and only the translation of the mouse information to serial has to be done.Finding a microcontroller with USB host or OTG capability is not to difficult, but making a USB host driver is a bit more complex than a USB device driver.

author: Kean
author_rank: Unknown
timestamp: June 12, 2025, 10:15:12 am
content: Quote from: pcprogrammer on June 12, 2025, 09:26:15 amWell, no. If some (many?*) USB mice can be made to talk PS/2 protocol via a passive adapter, then you just need a micro that talks PS/2 protocol and serial.One of the links on the forum I linked above goes to a article with just this solution (you also require the above mentioned adapter)https://hackaday.io/project/27575-ps2-to-rs232-mouse-converterhttps://en.wikipedia.org/wiki/PS/2_port#Conversion_between_PS.2F2_and_USB* apparently some fancier new USB mice no longer include PS/2 backwards compatibility, but I don't really think you will benefit from a fancy mouse used with a PC serial mouse port.

author: pcprogrammer
author_rank: Super Contributor
timestamp: June 12, 2025, 12:36:37 pm
content: Quote from: Kean on June 12, 2025, 10:15:12 amThat is true, but, like you indicated, you need a mouse that still has that ability. I know from way back that it was possible to just use a passive adapter to convert from USB to PS2, which I believe also worked for keyboards. But the mouse/keyboard has to be able to switch it's USB data lines to become PS2 lines. Not sure where they are, but I have plenty of these adapters, but probably also a couple of old mice that are PS2 to start with.I doubt that a wireless mouse that works with an USB dongle still provides this functionality. Never tried it though, so who knows.

author: squadchannel
author_rank: Frequent Contributor
timestamp: June 12, 2025, 01:51:22 pm
content: mouse depends on what you want to do with that computer.if it is a DOS machine, you will most likely not need a mouse.Of course, a USB mouse cannot be connected directly to a serial port, nor can a modern wireless keyboard be used with a PS/2 port.MOD:I found an interesting adapter.https://www.amazon.com/dp/B00HGI5JPA/

author: Kean
author_rank: Unknown
timestamp: June 12, 2025, 02:05:53 pm
content: There are tons of wired mice still available at low cost, and they very likely use the same silicon developed years ago that supports both USB & PS/2. The tooling and other NRE costs are long paid for, andlots of people don't need a fancy mouse for checking Facebook and watching cat videos. Although I guess that probably mostly happens on phones & tablet these days.Definitely the 2.4GHz wireless mice USB dongles, and probably a lot of wired gamer or multi-button mice do not support PS/2 protocol - but as I wrote above the software that runs on hardware with a serial mouse port isn't going to be able to use those mouse features.A used or NOS serial mouse is still quite possible to buy. A quick eBay search will bring up many results, although some asking prices are silly. As usual, it may take a little patience to find a good deal. Trying the local thrift store/op shop/Goodwill/flea market might turn up a result.My search results also included PS/2 to serial adapters - so some older PS/2 mice were clearly backwards compatible like the USB to PS/2 backwards compatibility. I had forgotten those even existed.

author: Kean
author_rank: Unknown
timestamp: June 12, 2025, 02:07:58 pm
content: Quote from: squadchannel on June 12, 2025, 01:51:22 pmYes, exactly the same item I just spotted in my eBay search for serial mouse. I bet I still have some in a box here somewhere.

author: pcprogrammer
author_rank: Super Contributor
timestamp: June 12, 2025, 05:36:49 pm
content: Quote from: Kean on June 12, 2025, 02:07:58 pmYeah, this type of old stuff remains somewhere in a box for decades. I'm sure that when I start digging I will find some too.

author: mariush
author_rank: Super Contributor
timestamp: June 12, 2025, 05:57:21 pm
content: If it's a USB mouse, the controller inside the mouse needs to support both USB and PS/2 ... usually the controller tries to communicate through USB and if it can't detect valid usb packets within some period of time, it assumes the protocol is PS/2 and falls back to that.You should be able to easily get older optical mice at goodwill or some other places with such controllers, and worst case scenario you'd just have to replace switches inside to get partially working mice back to 100% operational state.You can also buy new PS/2 mice from eBay, for example here's one for around 10-12$ plus shipping :https://www.ebay.com/itm/316041299670--I remember seeing some ISA usb controllers on Youtube on some of the channels that show older hardware and older games, and some dos usb drivers were shown ... but I don't remember exactly what channel was, sorry... either way, not sure if it's worth buying such card. A ps/2 controller card would be more common and use less resources.

author: cunningfellow
author_rank: Regular Contributor
timestamp: June 12, 2025, 09:37:39 pm
content: HidMan ?https://github.com/rasteri/HIDman

author: coromonadalix
author_rank: Super Contributor
timestamp: September 17, 2025, 05:49:13 pm
content: i'm astonished to see such efforts made to extend the oldies life, compatibility, peripherals, interfaceskudos

author: wraper
author_rank: Unknown
timestamp: September 17, 2025, 06:04:26 pm
content: Quote from: mariush on June 12, 2025, 05:57:21 pmYes, bottom of the barrel mouse based on specialized chip rather than MCU may still support PS/2 with a passive adapter. No chance for more expensive ones, especially those which have downloadable software.