I've tried three PS/2 to USB adapters in the past and they were all crap. Ultimately I gave up on them. They work fine most of the time but then randomly you'll get a stuck keypress and everything goes haywire. If you plan on using these adapters, I would recommend getting one and testing it out for a while to make sure it's going to work for you.

There are KVM switches that support both USB and PS/2 keyboard/mouse natively. They will probably work better. Serdashop sells a PS/2 mouse to serial adapter for your 486.

Plasma wrote on 2022-01-16, 13:04:

I've tried three PS/2 to USB adapters in the past and they were all crap. Ultimately I gave up on them. They work fine most of the time but then randomly you'll get a stuck keypress and everything goes haywire. If you plan on using these adapters, I would recommend getting one and testing it out for a while to make sure it's going to work for you.

There are KVM switches that support both USB and PS/2 keyboard/mouse natively. They will probably work better. Serdashop sells a PS/2 mouse to serial adapter for your 486.

Thank you for the info!

Are there any KVMs that you'd recommend? Or a brand? I'll definitely be getting that adapter. I have had success with PS/2 to USB converters in the past and I have a few laying around. It's true that some are better than others.

Edit: also, does this mean that the KVM can take USB and then convert it down the line to PS/2? I'm new to this aspect, and it would make my life a lot easier if this was the case.

I don't have any combo KVMs so I can't recommend any personally. ATEN CS84U and Black Box KV7021A-K are two examples. The Black Box is more expensive but it has audio switching and is "business-grade." But I can't say one is better than the other.

Both of those KVMs can accept either a PS/2 or USB keyboard/mouse, and connect to computers with either USB or PS/2 ports. The KVM will convert as necessary.

Whatever KVM you choose, make sure it includes the cables, or you factor in the cost of the cables since they are typically custom and expensive.

PC side I can recommend going down the PS/2 KVM route
Native PS/2 or AT rigs are no problem
but as Plasma said the Ps/2 to USB adapter is the tricky part.

I've an old no name adapter that came with generic wireless keyboard I think? works fantastic shame I cant find more to buy.
Cheap modern adapters are more software based that show up as HID device which shouldn't matter as your USB only computer is modern, but even still I find the adapter doesn't map keys to my UK keyboard correctly until past the login and will have no chance on a older rig.

KVM side I've got an Compaq 8 port although my cheap no name 4 port KVM actually supports more resolutions and frequency's
This is my 4 port unit. Dynamode seems to be a common brand it sells under but it's been round for years, I brought my first one in 2002 under a long forgotten brand.
https://business.currys.co.uk/catalogue/compu … -ports/P187740P

I've used Aten 8 Port KVM's at work plugged into Windows 2003 and newer servers using a mix of the PS2 and USB cables and works fine. Even the 2nd hand ones are bit pricey for my own use though.

Ps/2 keyboard wont cause any issues

USB mouse with a Ps/2 only KVM you'll need a optical mouse that still supports the PS/2 protocol, most modern one's don't. Those USB to PS2 adapters that used to come with a mouse are passive so if the mouse doesn't support Ps/2 then the adapter wont work.

Serial mouse it the big deal breaker. A few old business class KVM's do support converting Serial to PS/2 but not many, The retro scene has been working on a few projects for an adapter but a lot of us simply have a serial mouse that they use with that 1 rig

I've used a couple of different "Adderview" branded KVM's with my retro setup. They do serial mouse emulation perfectly. I've just had to make up the correct cables to go from the PS/ port on the KVM to the serial port. Most the adapters sold on ebay seem to have the incorrect pinout. I was using 2 4 port ones daisy chained, but now have a big 8 port one.
Andrew

I would confirm the suggestion to stick with a PS/2 only solution.
Regarding the 486 with serial port support, I could either recommend the PS2TOSERIAL adapter as shown here:
https://youtube.com/shorts/zV8uoAQW6NI

Or the "Serial to PS/2 adapter from necroware" as shown here:
https://youtu.be/1UNOzkzLU_w

As mentioned before, those adapters would support USB mice that still "speak" the PS/2 protocol. Which are quite much even nowadays!

A Belkin F1D066 would be your friend. I had a six port version way way back in the mid 00's. It was a KVM switch that had Serial and PS/2 on it. So I could connect up to six PC's of any type to the KVM. Looks like the one I linked to has AT AND Serial AND PS/2. Would be able to attach to a modern system(s) using USB to PS/2 adapter(s). I think there was a hotkey to hot-swap too like CTRL+SCROLL LOCK and then the # of the machine you wanted to use.

At my peak I had a six computer stack plugged into that thing into a Samsung SyncMaster 710MP TV/Monitor. All my video madness in one spot!
- Pentium III running windows 98 SE
- Pentium 1 running RedHat Linux
- 486 DX4 running DOS/Win311
- Compaq Deskpro 386 running DOS
- Compaq Deskpro 286 running DOS
- Generic XT Clone running DOS w/ Model F keyboard (was planning to get an XT to AT adapter for that one)

https://www.amazon.com/Belkin-OmniView-Keyboa … g/dp/B0044I6XLY

Another great one I had, if you use PS/2 adapters, was the Apex Outlook 480DX, which was an 8-port KVM with an OSD that could be triggered by hotkeys, and you could name all the computers on the OSD. It was PS/2 and VGA only though. I think it was CTRL+ESC to bring up the menu. I was limited to 4 because mine had damaged firmware from day one ( I bought it at Goodwill).