One for the hardware types.

On Fri, 14 Sep 2018 23:55:15 +0100, Dave Plowman (News) wrote:

Hmm. Mine is a combined USB-PS/2 one. I use a PS/2 keyboard and PS/2 mouse, and it's connected to two machines with USB. It doesn't have that booting problem on either Windows or FreeBSD.
Is the firmware up to date?

Not sure - have a look on their website.
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Possibly if it's one of those with a big mechanical switch, or relays. But most likely it's some logic gates redriving the signal, and they won't handle USB. So generally not.
Since this is uk.d-i-y, I suppose it might be possible to make an external relay box and hook it in to the KVM somehow...
Theo
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I've no problems with building something. A USB switch linked in to the KVM would be just fine. Perhaps I'll need to look for some circuits.
Is there any switched volts on the PS2 connectors on the KVM that I could use?
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Dave Plowman wrote:

Normally 4 out of the 6 PS/2 pins are GND, +5V, CLK, DATA (occasionally two DATA pins if designed to work with a Y splitter for keyboard and mouse on a single port, usually split green and purple, rather than one or the other)
<http://pinouts.ru/Inputs/PS2Mouse_pinout.shtml
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Since the mouse is USB 1.1, it's only 12Mbps. So a DPDT relay may get away with it. The main thing is whether each machine is happy with the mouse being hot(un)plugged each time you switch, or whether they get confused.
It is possible you might need to power down the mouse while you switch over, to make sure it restarts attached to the new machine.

If the switch was the other way (two mice, one PC) they could be switching PS2 power. But the other way both PC outputs are inputting power to the KVM, so you can't tell.
There might be an LED or something you can tap into to extract which output is enabled.
Theo
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On 14/09/2018 14:57, Dave Plowman (News) wrote:

Pretty unlikely

The basic passive adaptors won't work since they require the mouse to switch between PS/2 and USB. With the adaptor on they run USB protocol.
There are however active adaptors/protocol converters that will convert a true USB mouse and KB to PS/2 - I did get a seriously expensive one from Black Box in the hope of being able to run a modern gaming KB on my PS/2 KVM - alas it did not seem to recognise the more sophisticated keyboards. It did however work with the mouse. So chances are that would do it for you also.
https://www.blackbox.co.uk/gb-gb/fi/1307/12426/USB-to-PS-2-Converter
(not sure if there is anything else similar out there that is cheaper - but there might be. Failing that I could flog you mine ;-))
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On 14/09/2018 14:57, Dave Plowman (News) wrote:

What sort of switch does the KVM use? Can you attach a new switch to it that operates at the same time and wire up the connections as required on the new switch? Just a passive switch no electronics.
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A sequence of key presses on the keyboard. Which I like - saves having a switch cluttering up the place.

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On 14/09/18 14:57, Dave Plowman (News) wrote:

Yeah, but....
Can't you use VNC? Allows use of both machines at the same time, one windowed inside the other.
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Not ideal. I don't always want them both on. They get switched off when not in use.
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No idea, but I have seen hardware converters for both directions on the web, and I do not mean just connector changingthere is one here I have that allows one usb to handle a ps2 mouse and a keyboard on the same lead. Brian
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On 15/09/2018 07:46, Brian Gaff wrote:

Converters that allow PS/2 devices to be connected to a computer via USB are fairly common - although many are crap. A common failing for example is not supporting the \ key on UK keyboards. Others work but suffer random lock-ups.
The converters for going the other way (i.e. USB peripherals into a pair of PS/2 connections) seem far rarer. The only reasonable one I found was the pricey black box one which works quite well but does not seem to support the flasher keyboards.
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