Oh wow, what a blast from the past. Around the year 2000 or 2001 I got an optical mouse as a present (either birthday or new year, can't remember). I really wanted it for a long time because playing StarCraft with a mechanical one was rather painful.<p>Needless to say it was a USB mouse and I only had ps/2. I purchased an adapter but it never worked despite spending a lot of time trying and testing it with different PCs and mice.<p>Then I took the adapter to an electronics repair shop. They opened it up and explained to me it was fake: it just connected the wires without any circuitry for the real USB support. They had no idea why anyone would manufacturer such a thing.<p>Well, now I know why. I spent quite a long time thinking I was sold a counterfeit adapter.
Once had a very awkward conversation with a sales person in PC World.<p>I had been given a old retired server from work to take home and learn with... only problem was it had no USB.<p>I was asking for a PS2 keyboard, he said they don't sell them but I could use any USB keyboard, I told him I don't have any USB ports and I needed a PS2 keyboard.<p>After awhile of him going back and forth with his manager, only to return to tell me i can use USB, It turned out he thought I was trying to buy a Play Station 2 keyboard and he'd never heard of PS/2!
Some more details (and interesting historical perspective) can be found here: <a href="https://superuser.com/questions/704920/how-to-determine-if-usb-mouse-supports-ps-2" rel="nofollow">https://superuser.com/questions/704920/how-to-determine-if-u...</a><p>Apparently around 2014 the vast majority of mouses and keyboards were dual-protocol, but in 2019 the first reports of them being USB-only started appearing. I suspect a lot of the cheapest mouse SoCs are still dual-protocol as they worked when first designed, and they just kept producing them without any changes.<p>Pinout and explanation of how they detect protocol here: <a href="https://retrocomputing.stackexchange.com/questions/28288/how-did-early-green-ps-2-to-usb-mouse-adapters-work" rel="nofollow">https://retrocomputing.stackexchange.com/questions/28288/how...</a>
I have an old Roland S760 sampler from the early 90s. One of the innovations Roland made in this (lower cost) space was to add the ability to hook up a monitor and a mouse, to make chopping samples and programming patches much easier than peering at a tiny screen like on an Akai S1000 of the time (which I also have), or even worse on the S760's tiny two-line display<p>The mouse connector is MSX, which are very difficult to find these days, so mine came with a DIY MSX->PS2 connector. Sadly the PS2 mouse it came with was on it's last legs, so I wanted to replace it with something more modern. All I could find at the time were MS mice that came with a USB-PS2 connector. When I plugged it in, it barely worked and I could never understand why.<p>I did finally manage to track down a NOS PS2 mouse and it worked perfectly again. Until this post, I never understood just WHY it didn't work, so thank you!<p>The S760 is a fantastic sampler. It's kinda like a JD990 but as a sampler and without the full synth engine complexity. Made famous by Daft Punk and a lot of others as the S760 digital multimode filter became one of their signature sounds.
An active converter is needed to use modern USB on retro computers. I made one a few years ago for many different computers.<p><a href="https://github.com/dekuNukem/USB4VC" rel="nofollow">https://github.com/dekuNukem/USB4VC</a><p>There's also a more recent project called HIDman, but only for PCs.<p><a href="https://github.com/rasteri/HIDman" rel="nofollow">https://github.com/rasteri/HIDman</a>
I have a keyboard from my first 386/33 computer. It can be connected to my current Mac through a sequence of adapters: DIN5 -> PS/2 -> USB-A -> USB-C.<p>I am looking forward to extending my sequence of adapters in the future.
Keyboards from the late 90s and early 2000s often did something similar. The controller supported both PS/2 and USB and the keyboard would come with a PS/2 plug and a passive adapter. That's why if you're trying to use a PS/2 keyboard designed prior to the introduction of USB (like a Model M) on a modern computer, you need to make sure to get an active PS/2 to USB adapter that actually translates the protocol.
This is similar to how a (cheap) DisplayPort-to-HDMI adapter worked, the adapter itself is completely passive.<p>Many devices with DisplayPort output support multimode, which allows the device to switch from outputting DP packets to outputting TMDS-based HDMI or DVI signals. You'll sometimes see a ++DP logo on these ports.<p>This is also why you don't see a cheap HDMI(source)-to-DisplayPort(sink) adapter, the smarts just aren't built into the source device.
Sligthly (un)related: The other day the builtin keyboard on my rather new Thinkpad X1C 12th stopped working. I connected a USB keyboard and tried to figure out whether there was an error in Linux kernel ring buffer or anything else explaining the problem.<p>To my surprise the internal keyboard is not even USB, but i8042. Not a hardware guy, but I had silently assumed everything is USB these days. I guess i8042 is the PS/2 protocol TFA is talking about?<p>(No error found, but after a reboot it has been working again.)
I suspected something list this, so these always scared me.<p>Actually, magic always scares me. I was putting together an LTE internet gateway from a Mikrotik device flashed with OpenWRT and was confused about how the SIM card slot on the main board interacts with a mini PCIe LTE modem. I <i>looked at the mini PCIe pinouts</i> and discovered the modem is actually USB (mini PCIe has pins for this) and mini PCIe has pins that are wired to the SIM card. I later ran into an issue where the card wouldn't work, but if I tape over the USB3 pins, it would drop to USB2 (still enough bandwidth for LTE) and work.
Didn't those adapters exist in both directions? Green in one and violet in the other? I have the feeling if I started to dig in my treasures I should still find some. One way to avoid e-waste is not to throw anything away...
The best part about Microsoft mouse USB=PS2 adapters is Microsoft made several mice models with incompatible wired differently adapters that look the same from the outside :)
I always assumed these were active devices doing some quick translation between USB and PS/2 but after dealing with USB controllers, this would have been exceptionally difficult (at the time) to fit inside of a dongle barely larger than the connectors.
I am using an USB-to-PS/2 adapter right now.<p>My mouse is a Logitech MX-500, which is the last model I have with PS/2 support, the next model MX-510 was USB only.<p>The motherboard is an MSI B550 TOMAHAWK, the computer was assembled just a few months ago.<p>The mouse still works and it has proven to be more reliable than modern ones.
The very old Microsoft IntelliMouse are some of the best designed mice in the world. They always just work as designed. (Until you found someone with a glass desk, then it was time for a mousepad.)<p><a href="https://en.wikipedia.org/wiki/IntelliMouse" rel="nofollow">https://en.wikipedia.org/wiki/IntelliMouse</a>
Interesting. I have a USB IBM TrackPoint Keyboard that I use with a USB to PS/2 mouse and keyboard adapter. I bought the cheapest adapter I could find and I was surprised it worked. Now I know why—the keyboard must have a chip that switches between the two protocols.
The motherboard on my old Intel 4790K would only go into the BIOS with a keypress from a PS/2 keyboard, not from a USB one... That computer is still in service, a friend uses it for general browsing, etc. When I gave it to him, I gave him the 3 purple keyboard adapters I had and an explanation to keep track of them.<p>I couldn't get one anywhere locally, even at Fry's Electronics at the time before they closed (man that place was a ghost town towards the end). I don't know if the keyboard adapters were the same as the mouse adapters, but I do remember that some would work with some devices and not others.
A note about even older AT keyboard connections they should not be hot plugged! Some older motherboards had a fuse soldered in that would blow if the keyboard was hot plugged. Fixed several in the days.
My whole life has been a lie... And yes I do have a drawer with several of these alongside VGA adapters and anything else I might need during the end times.
Yes, this is a common issue for folks who are into vintage mechanical keyboards. Be aware that you almost always need an /active/ USB to PS/2 converter. For the Model M, many keyboard generations had detachable cables that used the SDL standard and there are several options for in-cable conversions based on Blue Cube, TeensyUSB, or similar setups to allow you have a "SDL to USB" cable.
There's a purple adapter too that came with some keyboards. It looked like it came out of the same molds, so I suspect it's a similar situation.
This is really good timing because I just naively bought one of those little green adapters for test for three apparently fruitless causes -- a mini disc recorder, a vt520 and a vt525. I now have some hidmans (hidmen?) on the way with some hope that I/we someone can figure out whats missing to get it working with the VT52{0,5}.
The Atmel AT90USB162 chip multiplexed the USB D+/- pins with an SDATA and SCK PS/2 port. It is possible to build a "serial" to PS/2 or USB bridge device with very few components. The part seems to still be available from Microchip.
Funny enough PS/2 has found its niche and is included on most “gaming” motherboards because - less latency than USB! ps/2 has higher system priority
I wonder if you could bit-bang PS2 from the host side - though this is probably one of those things where we need to "consider if we should."