KVM switches used to be a huge and super important (and expensive) thing in rack server farms back when every rack or every few racks had a pull-out tray with a keyboard and a monitor. Technology moved on. First the tray and monitor disappeared with KVM-over-IP, which saved many trips to the server room. Then the KVM switches themselves disappeared, as manufacturers integrated out-of-band remote access into the servers, first with add-on boards, then onboard and finally on-chip (this is what Intel AMT does, when it isn't busy running rootkits).
The little two-PC switch box the article refers to (I think) was always a spillover from the server KVM technology, except with a very small market and more difficult to make. Servers don't need sound and are fine with just VGA video. Home computers want USB (which variety?) and audio switched, or high bandwidth signals that are very touchy about interference or suddenly being connected to a different device like HDMI, Displayport or Thunderbolt. And then people want the stuff for cheap.
> signal switches with arbitrary bandwidth remain available: analogue relays
Have you tried that? Cut a HDMI cable in half and splay it out, then try switching that to another display. See what happens. If it were that easy, it'd be around (or you'd just be building it yourself).
Anecdotal, I still use a KVM, for a specific use case. My PC has 2 monitors. My 1st monitor is standard usage, but my 2nd monitor is also used by my partner's PC. If she wants to use her computer, she gets the 2nd monitor (and the speakers) but otherwise I got a 2nd monitor to use.
Practically, it saves me from having to use another set of speakers (you would not use 2 sets of speakers at the same time and I usually use headphones) and it also saves me from having to have or use 3 monitors which takes up more space and costs more.
My partner doesn't use her computer a lot. When she does, all the hardware is available for her. I use the 2nd monitor during development, gaming, watching movies, and RDP session.
As per some comments, I don't see how a VM would replace this use-case but I do understand its niche. Still, it saves us space.
Fair point, but I had this KVM lying around as I bought this back in ~2007 when I was using a Linux server as 24/7 desktop (including even some Windows apps via WINE) as well whereas I put my Windows desktop off. I was using one keyboard/mouse/speakerset. While I'm not using the keyboard/mouse function anymore, we are using the speaker function.
Also, that feature you mentioned, while it works with some RCs (generally "source" or "input" key), doesn't take into account all the inputs which I am not using. So I need to go through a list of 4 or 5 devices including DVB-C cause yeah my monitor has that support even though I've never used that input. That's annoying.
It gets annoying the more often you gotta switch. For employees of government (like the mentioned example of the Pentagon) that's gonna be more often than not. Any downtime is then a waste because even if its merely 20 seconds back and forth it quickly adds up.
It could even make sense to have KVMs in businesses where they want to keep certain data strictly internal. But as long as companies aren't being punished for data leaks that doesn't have priority. Perhaps we'll eventually see a rise again of KVMs.
Yeah, got to agree it's far from perfect - I use it for infrequent direct access to the server under my desk, and it does mean messing around with having extra input devices etc.
You are not alone in this. For years my Partner and I had separate machines on a KVM. It was only when our Daughter moved out and her desk became free in our study that we no longer needed this setup.
I use that term because its gender neutral and relationship neutral. I find it irrelevant to a discussion whether we are married or not, or a member of the LGBT community or not. However I don't hide my gender or my partner's gender (ie. I use he and she forms due to practical reasons).
I have always assumed "partner" either means "business partner" or that the person is signaling both (1) "I'm gay" without being overt and (2) "I'm resent society's prevailing idea of marriage." at the same time.
One can use "spouse" or "significant other" to avoid the perception of being passive-aggressive.
I'd encourage you to give others the benefit of the doubt. Without other evidence, that "perception of being passive-agressive" is only that, a perception.
And wired up the HDMI of two machines to output ports 1 & 3[1]. Then wired up the HDMI to the display to the input port (so effectively using the switch 'backwards'). As you are just simulating unplugging and re-plugging in the HDMI cable from each machine, via the switch, then surely this would work?
There would be a bit of delay after switching as the HDMI/HDCP handshake completes, but unless you are switching every few minutes it should be usable?
If it does work, then you've got 6 pins in the switch left to play with which could be used to switch usb devices (via a downstream hub)
I've not done this, but have thought about it for a while now.
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[1] Not ports 1 & 2 as you want to ensure total electrical isolation between the devices during switching.
Not likely. If the cables are short you might get away with it but not likely.
The problem you will have is that the signals require high bandwidth and the cables are carefully designed to have low crosstalk, high immunity to noise (both via twisted pairs) and a 100 ohm characteristic (dynamic) impedance (how the cables are constructed, insulation thicknesses, how they are twisted).
DB-25 switches work for simple single ended low frequency signals. The physical switch will wreck havoc with the interpair skew, far-end crosstalk, attenuation and differential impedance.
HDMI 1.3 defines two cable categories: Category 1-certified cables, which have been tested at 74.5 MHz (which would include resolutions such as 720p60 and 1080i60), and Category 2-certified cables, which have been tested at 340 MHz (which would include resolutions such as 1080p60 and 2160p30). Category 1 HDMI cables are marketed as "Standard" and Category 2 HDMI cables as "High Speed". This labeling guideline for HDMI cables went into effect on October 17, 2008. Category 1 and 2 cables can either meet the required parameter specifications for interpair skew, far-end crosstalk, attenuation and differential impedance, or they can meet the required nonequalized/equalized eye diagram requirements. [1]
Would it have enough bandwidth? High speed connections have some careful engineering (for instance, maximum distance without a twist on a differential pair), that I doubt that ancient box has.
Also, there are sequencing requirements. Look carefully at a USB-A plug, and you'll see that the power and ground traces are longer than the data traces: when plugging the USB cable, the power is connected first, before the data; when unplugging, the order is reversed. HDMI probably has similar requirements, perhaps with more steps. Again, I doubt that ancient box can do that.
I believe this is also the case. The only organizations that can get exemptions from the HDCP Alliance (DRM Cabal) for devices that effectively circumvent encryption are for high end broadcast gear. Nothing precludes making a 4k KVM. Infact, a mid range AV main unit could probably route 4k KVM.
I actually bought a 4-port USB/HDMI switch model fairly recently. It's really just a clutter and convenience thing. I have a few computers, including Raspberry Pis, that I just fiddle around with sometimes. While I could do things in different ways, it's just simple to have one monitor, keyboard, and mouse and plug the computers into the switch.
Do you have time to link the specific product if it has been working well for you? I personally wouldn't even mind a referral link though most get downvoted, especially if they lack a disclaimer.
Something that can reliably connect to random/miscellaneous projects would be really useful to me!
This does not meet the requirements of a modern workstation by my or the original article's requirements. This is limited to 1080p. We're looking at 4k as a minimum.
The easiest solution is to just buy an HDMI switch(there's loads of them, even ones which work with 4K signal, and they don't disrupt DHCP) and a USB switch. Total solution should fit in about 40-50 dollars.
Are there any that don't suck bogwater? We've tried a handful for our conference rooms, and they are all universally flaky, with signal dropping randomly all the time.
Seriously though, I am a regular user of DVI and VGA KVMs, which have served me well over the years, but now as I migrate to HDMI or DisplayPort connectors and higher resolutions, I'm finding myself having to re-think how I hook everything together.
My windows laptop has only VGA out, so I hook up a second monitor via displaylink (usb -> DVI).
I tried plugging the cable into my KVM switch and it worked okay on the Windows 10 side but there was some hot-plugging kernel panic when switching to Linux (must file a bug report!)
So perhaps the future of KVM switches doesn't need video connectors such as VGA/DVI/DP if USB-C -> HDMI (as smartphones are adopting) becomes universal.
At work, we have at least the first 30 racks with good 'ol VGA KVM's (no IP) and tray monitor/keyboard/touchpad, despite at least half of the servers having IPMI. Ain't going anywhere anytime soon.
And no, no one needs 4k where a KVM belongs (which is in a server room).
I needed a 4k switch. I had a nice monitor and a Linux and Windows laptop. I used the Win laptop for gaming and the Linux machine for pretty much everything else.
There are a few in the $500+ range I have not tried, but you are wrong, there are use cases for 4k switching. I mean, do you really want to have two 4k monitors next to each other when you could just have one for half the cost?
Do you really want to have two computers where only one is ever in use, when you could have just one for half the cost?
Your setup is rather peculiar, and wastes a computer. It is usually done with dual-booting or virtualization, while multiple inputs (which I bet your screen has) or HDMI switch could handle it as well (although without handling keyboard/mouse).
KVM's were designed for server environments, sold to server environments, and only take server environments into consideration where VGA+USB will remain the status quo for years to come.
If you're really set on a KVM, take a 4k-capable standalone HDMI switch, a USB "switch" (https://www.amazon.com/IOGEAR-Computer-Peripheral-Sharing-GU..., or a USB KVM), and an arduino to strap it together as a unit. Unless servers do away with VGA (hahah, no), I doubt you'll find a product for an affordable price that does what you want.
Does the 4k monitor have multiple inputs? If it does, then connect both laptops to different input channels and switch inputs on the monitor as needed. Then presumably all you would need is a USB switch for keyboard and mouse input.
I have often wondered why no one offers wireless keyboard/mouse combos with multiple USB fobs and a switch on the keyboard to change which fob it talks to.
The little two-PC switch box the article refers to (I think) was always a spillover from the server KVM technology, except with a very small market and more difficult to make. Servers don't need sound and are fine with just VGA video. Home computers want USB (which variety?) and audio switched, or high bandwidth signals that are very touchy about interference or suddenly being connected to a different device like HDMI, Displayport or Thunderbolt. And then people want the stuff for cheap.
> signal switches with arbitrary bandwidth remain available: analogue relays
Have you tried that? Cut a HDMI cable in half and splay it out, then try switching that to another display. See what happens. If it were that easy, it'd be around (or you'd just be building it yourself).