I was using an Aten CS-122, and grew tired of its quirks and the need for yet another wall wart. The answer for me was a plain old dumb data switch.

Pierre32 wrote on 2022-02-21, 03:14:

I was using an Aten CS-122, and grew tired of its quirks and the need for yet another wall wart. The answer for me was a plain old dumb data switch.

I'm almost there myself.

Do you get any stuck mouse issues, and you obviously need to be switched over before powering on, correct? Or are there some switches that mitigate one or both?

Damn, I picked up an Aten cheap hoping it would work well when I got a lot set up... good thing I still got the bag the yard sale dude put it in, I'll have to get my $2 worth out of that. 🤣

I've got a couple of 2 into 1s I'll report on if I get round to messing with them, but all my projects seem to move glacially slow.... well maybe that's the thing "all"... like a 486 with 250 browser tabs open 🤣

BitWrangler wrote on 2022-02-21, 03:29:

Damn, I picked up an Aten cheap hoping it would work well when I got a lot set up... good thing I still got the bag the yard sale dude put it in, I'll have to get my $2 worth out of that. 🤣

I've got a couple of 2 into 1s I'll report on if I get round to messing with them, but all my projects seem to move glacially slow.... well maybe that's the thing "all"... like a 486 with 250 browser tabs open 🤣

It might depend on the year? Again, mine is pretending to do PS/2 <-> USB, so if you have an older one, this might not be an issue at all.

My suspicion is that one or two manufacturers came up with a schema for KVMs in the early 90s, basically sold the firmware design and passed it around for 20 years, and the result is compounded bugs inherited over like 3 generations of hardware. Which explains why when people complain to manufacturers that their product doesn't work, they respond with "this is functioning as intended"... nobody knows how to patch 30 year old firmware (just a guess).

Also the fancypants motherboard I have has this option in the BIOS. I have no idea if this could or would affect any KB issues, but if anyone knows if I'm scanning too fast or not fast enough, let me know (seems weird that this would matter but hey, grasping at thin air here)

Mid 90s up native PS/2 keyboards I'd have it on 12Mhz, AT 90s keyboards with adapter on 8, early AT keyboards on 6... not sure what you'd get 16Mhz out of, maybe 2000s HP keyboards, they may have stuck with PS/2 longest. I'd kinda think 12 is good guess for what kvms would like/use.

I need to test a couple KVM switches I have.

One is a Belkin 8-port. The model is OmniView Pro 8-port.
It is vga, ps/2, and serial. Supports changing ports through a couple buttons on the front, through a double tap of the Scroll Lock and then up or down arrows or double tap of the scroll lock and then spacebar to bring up the OSD.
using the hotkey combos should not pass anything to the active computer unless you have some random game that uses Scroll Lock for some reason.

The other is from a server rack which I got when cleaning out an office. It is an Avocent DSR1021.
The input is ps/2, it outputs to VGA and the cables it uses come in ps/2 and USB variations. Max resolution for local / analog control is 1600x1200. For remote, it is 1280x1024.
It is a local and network KVM in one. The switching is through the built in web interface.

Any half-decent KVM that uses ps/2 or serial should be keeping the ports alive on machines you are not currently interacting with.

If not, then a cold boot of the machine would be required each time you switch to said machine.

dumpsterac1d wrote on 2022-02-21, 03:19:

Pierre32 wrote on 2022-02-21, 03:14:

I was using an Aten CS-122, and grew tired of its quirks and the need for yet another wall wart. The answer for me was a plain old dumb data switch.

I'm almost there myself.

Do you get any stuck mouse issues, and you obviously need to be switched over before powering on, correct? Or are there some switches that mitigate one or both?

Mine's technically a "KV" because I use separate mice for the DOS and 9x machines, just sharing the KB & monitor. So unfortunately I can't report on mouse behaviour. Can confirm that you need it switched to a machine before booting it though.

Taking a chance with an ancient D-Link DKVM4.

It has hotkeys which doesn't make me extremely happy, but the hotkey is scroll lock, scroll lock which will never be hit by accident. It also requires power, which to me is a very good sign that it buffers signals rather than interprets them, and all the "juice" so-to-say should go to the peripherals should they need them. Downside is monitor resolution, which doesn't go to the full XGA/ridiculous range, but I don't care, the max res I want to use with the Dell Trinitron is 1024x768 anyway.

I'll report back should it actually be sent to me (estimated delivery is a month out), but it was cheap enough to not worry too much about.

Another issue I'm seeing is that KVMs don't adapt ps/2 to USB very well on either end (early USB mice with explicit PS/2 support like the intellimouse don't work with adapters, and your standard PS/2 to USB passive jobs don't work). I was honed in on a StarTech SV411k but several reviews mentioned these didn't work, and I need both.

Here's hoping this D-Link will be OK.

Edit: After a further and more intense look at the manual, the D-Link DOES indeed look like it works with USB mice with PS/2 compatibility baked into them, like the Intellimouse. This is an extremely good sign that PS/2 to USB adapters will also work. If this one doesn't pan out I will be super crestfallen so wish me luck!

Got the DKVM4. It's completely transparent and works perfectly. It even resolved some other issues I had that might or might not have been related to the other KVM I had, which was some noise coming through the VGA sync pin (shimmery edges).

Some thoughts:

• If you're picking one up, be sure it has the power supply, or at least you know how to pick power supplies from specs.
• This works on devices like the Microsoft Intellimouse Optical, which have a USB cable but *explicitly* state they just need a passive adapter to get PS/2
• This works adapting at the other end to USB. I can't confirm it works with all PS/2 to USB devices, but a pretty generic Y-cable I had lying around works perfectly
• The device is great because you can use generic dual PS/2 + VGA KVM cables from any manufacturer (just be sure you're getting M to M cables)
• No issues whatsoever with canceled input on the keyboard, straight up does what it says it does. Played an hour of Unreal Tournament and 20 minutes of Keen 3 with no issues at all
• Sucks that you have to cycle through all sources, but a very small price to pay for a device that works.

So it looks like the older D-Links are the ones to get, for anyone who's looking up this topic in the future. There may be others, but until another one emerges that "just works", allow me to save anyone the cash hit of buying devices that don't work, or the energy involved in looking this topic up.

I have the Aten CS1758 and never had any issues.
KVM Switch Recommendations?
https://www.aten.com/de/de/products/kvm/rack- … uMaAn3GEALw_wcB

Using an Aten CS64A also no problems until now.

Using an old 4-port Blackbox Servswitch Wizard SSW4 (P/N SW652A) nowadays. Never had any issues whatsoever with it. It happily accepts combo USB/PS2 keyboards, which some switches I tried earlier had issues with.

There's no image degradation that I can see at least, using the supplied 2m KVM cables, even in high resolutions. It can also be used with regular VGA cables and male to male mini-DIN ones for keyboard and mouse. The manual contains pinouts/schematics for any special cables/adapters that might be needed, for example if you want to build a remote control. There are no exotic connectors, just mini-DIN and D-subs.

According to the manual, it can do PS/2 -> serial conversion, to use a PS/2 mouse with a RS-232 input. Haven't tried it myself though. Unsure if it also can do it the other way around.

It doesn't switch audio, but solved that with a DIY external passive mixer. It consists of a piece of perfboard, resistors, and a bunch of 3.5mm TRS jacks. Easy enough for anyone to put together.

The only downside is that it's quite bulky. There's lot of air in it though, successfully modded mine to less than half the original size:

skel2raw wrote on 2022-03-10, 12:47:

I have the Aten CS1758 and never had any issues.
KVM Switch Recommendations?
https://www.aten.com/de/de/products/kvm/rack- … uMaAn3GEALw_wcB

I finally had a back-and-forth regarding my Aten CS84U with Aten support. They replicated all issues I had with PS/2 outputs, which is good and bad. Good that this might be resolved in the future, bad that the engineers didn't notice canceled key-holds and stuck keypresses in the years the product has been sold. Another issue is they blamed my USB keyboard (which is the Unicomp Model M New SSK) for some of it because it had "non-standard switches" (took that to mean the key actuation mechanism wasn't supported? Lol) and the mouse for having too high a DPI. They wanted me to purchase cheap devices to try the product. Like I said, there are some things I appreciate, like their support actually taking my ticket seriously, but calling the Unicomp SSK a non-standard keyboard is a little rich. I communicated that my main issue is that if the device has caveats and doesn't work with what i'd consider to be pretty standard USB input peripherals, that should be relayed to the consumer and not just something held back until the person opens up a support ticket.

This one you linked to looks like a dream, switching audio, having a lot of outputs, etc, but considering my experience with their other products I'd rather just not.

The D-link DKVM4 is great, only issues are ones of convenience, like having to press a button 3 times to switch to a previous input, it having a power brick, and not having audio. But it works 100% as intended, not affecting rollover, no canceled keys, no stuck keys, no mouse interrupt issues, no video noise issues.

Thank you for the info on the DKVM-4!!! I have been searching for a KVM that passes through the PS/2 signals without an emulation layer. This unit absolutely does that. I use ps2x2pico with a modern USB mouse to get smooth hi-res 200hz PS/2 polling on my retro machines. This KVM passes through those signals with no issue. Many of the other period units like Raritan use an emulation layer that is not only laggy, but reduces the resolution/polling. It was miserable.

Thanks again!