J
Jonathan Mars
Arno said:
I didn't mean physically unplug/plugin, I meant they are seen as
disconnected on the previous computer when you switch to the other
computer. Still, don't get what you mean by simulated.
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I didn't mean physically unplug/plugin, I meant they are seen as
disconnected on the previous computer when you switch to the other
computer. Still, don't get what you mean by simulated.
J
Jonathan Mars
Sam said:The real reason that the better KVMs simulate the keyboard and mouse
for the PCs those arent currently switched to is so you can boot those
other PCs without them whining about no mouse or keyboard being present.
OK, now see what is meant by "simulate". One problem I have had when you
boot a PC on a KVM without it being switched to that PC is that if you
use a CRT the refresh rate will only be at 60hz. If you boot with the
KVM switched to the booting PC it will set the refresh rate correctly to
whatever you set. That's how it has been with both my KVMs anyway.
J
Jonathan Mars
Arno said:It is quite possible for them to "whine" about not keyboard or mouse
being present after bootup. As I said, I have seen it.
Arno
I've never seen XP or Vista whine, it still boots fine with no whining,
you just have no mouse or keyboard access. Let me guess, you are talking
about Linux OS whining?
J
Jonathan Mars
Rod said:Thats just plain wrong. The better ones do simulate the keyboard and mouse for
the computers that dont currently have the keyboard and mouse switched to them
so they dont start whining about no keyboard and mouse when they boot etc.
It's wrong and right.
http://en.wikipedia.org/wiki/KVM_switch
One limitation of mechanical KVM switches is that any computer not
currently selected by the KVM switch does not 'see' a keyboard or mouse
connected to it. In normal operation this is not a problem, but while
the machine is booting up it will attempt to detect its keyboard and
mouse and either fail to boot or boot with an unwanted (e.g. mouseless)
configuration. Thus mechanical KVM switches are unsuitable for
controlling machines which may reboot automatically e.g. after a power
failure.
Most active (electronic) KVM devices provide peripheral emulation,
sending signals to the computers that are not currently selected to
simulate a keyboard, mouse and monitor being connected. These are used
to control machines which may reboot in unattended operation. Peripheral
emulation services embedded in the hardware also provides continuous
support where computers require constant communication with the peripherals.
D
DevilsPGD
In message <[email protected]> Ed Light
That would be one of those "weird" issues when a cheap KVM plugs and
unplugs a keyboard and mouse rather the emulating one internally.
Find yourself an active KVM and you won't have this issue.
It used to be each to tell the difference, if it has a switch or push-in
buttons it's always mechanical, if it had the ability to change devices
from the keyboard it was active.
It's tough to find in the specs these days though as the devices have
gotten much closer in operation, excluding those weird boot related
issues.
If it's less then $20 of molded plastic and doesn't have an external
power source then it almost definitely is a passive type like the old
mechanical ones of yestercentury.
*Weird* issues?
My KVM needs me to boot the 1st computer and wait until it's totally
into Windows before switching over and doing the same with the other
(visiting) computer. Otherwise a little later the mouse and keyboard can
freeze up.
That would be one of those "weird" issues when a cheap KVM plugs and
unplugs a keyboard and mouse rather the emulating one internally.
Find yourself an active KVM and you won't have this issue.
It used to be each to tell the difference, if it has a switch or push-in
buttons it's always mechanical, if it had the ability to change devices
from the keyboard it was active.
It's tough to find in the specs these days though as the devices have
gotten much closer in operation, excluding those weird boot related
issues.
If it's less then $20 of molded plastic and doesn't have an external
power source then it almost definitely is a passive type like the old
mechanical ones of yestercentury.
D
DevilsPGD
In message <[email protected]> Jonathan
That would be because the computer cannot query the monitor's
capabilities, so it assumes the worst.
A better KVM seems to handle this nicely, providing accurate monitor
capabilities, or at least providing it's own capability set.
Mars said:OK, now see what is meant by "simulate". One problem I have had when you
boot a PC on a KVM without it being switched to that PC is that if you
use a CRT the refresh rate will only be at 60hz. If you boot with the
KVM switched to the booting PC it will set the refresh rate correctly to
whatever you set. That's how it has been with both my KVMs anyway.
That would be because the computer cannot query the monitor's
capabilities, so it assumes the worst.
A better KVM seems to handle this nicely, providing accurate monitor
capabilities, or at least providing it's own capability set.
D
DevilsPGD
In message <[email protected]> Arno Wagner
From the user's point of view that's not how a KVM "shares" a monitor,
keyboard and mouse though, and from the looks of it the original poster
seemed to be looking for a KVM-like switch rather then a true
device-aware share.
I've only used active KVMs for a long time now and haven't gone over to
USB on my servers yet, but as I understand it, most/all of the KVMs on
the market hot-plug the USB ports, rather then emulating a virtual
device for each port and redirecting the input as needed. This might
have changed though since it's been at least a couple years since I went
USB-equipped KVM hunting, and it was this restriction that pushed me
back to PS/2.
USB is plug and play by design, if your computer can't handle USB
devices being disconnected and reconnected, replace the drivers, your OS
or your computer.
That is not sharing. That is just unplugging and re-plugging.
Sharing means concurrent access and you cannot have two masters
in a single-master bus.
From the user's point of view that's not how a KVM "shares" a monitor,
keyboard and mouse though, and from the looks of it the original poster
seemed to be looking for a KVM-like switch rather then a true
device-aware share.
I've only used active KVMs for a long time now and haven't gone over to
USB on my servers yet, but as I understand it, most/all of the KVMs on
the market hot-plug the USB ports, rather then emulating a virtual
device for each port and redirecting the input as needed. This might
have changed though since it's been at least a couple years since I went
USB-equipped KVM hunting, and it was this restriction that pushed me
back to PS/2.
For simple storage that does not require configuration, yes.
As all confiuration is normally lost when unplugging and
replugging, KVMs typically simulate KBD/mouse for each
attached computer. This can lead to rather wired compatibility
issues.
USB is plug and play by design, if your computer can't handle USB
devices being disconnected and reconnected, replace the drivers, your OS
or your computer.
E
Ed Light
DevilsPGD said:If it's less then $20 of molded plastic and doesn't have an external
power source then it almost definitely is a passive type like the old
mechanical ones of yestercentury.
Belkin Flip.
http://www.newegg.com/Product/Product.aspx?Item=N82E16817394016
--
Ed Light
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D
DevilsPGD
In message <[email protected]> Ed Light
An example of a bad one?
From the reviews: "I have found that if you're not switched to a pc
while it's booting, it may miss detecting the mouse and the mouse
pointer might be frozen"
An example of a bad one?
From the reviews: "I have found that if you're not switched to a pc
while it's booting, it may miss detecting the mouse and the mouse
pointer might be frozen"
E
Ed Light
DevilsPGD said:In message <[email protected]> Ed Light
An example of a bad one?
From the reviews: "I have found that if you're not switched to a pc
while it's booting, it may miss detecting the mouse and the mouse
pointer might be frozen"
It's the one I was posting about, that I have here.
That review was by me.
--
Ed Light
Better World News TV Channel:
http://realnews.com
Bring the Troops Home:
http://bringthemhomenow.org
http://antiwar.com
Iraq Veterans Against the War:
http://ivaw.org
http://couragetoresist.org
Send spam to the FTC at
(e-mail address removed)
Thanks, robots.
R
Rod Speed
Jonathan Mars said:Rod Speed wrote
It's wrong and right.
Nope, just plain wrong.
One limitation of mechanical KVM switches
None are that primitive anymore and havent been for a hell of a long time now.
is that any computer not currently selected by the KVM switch does not 'see' a keyboard or mouse connected to it. In
normal operation this is not a problem, but while the machine is booting up it will attempt to detect its keyboard and
mouse and either fail to boot or boot with an unwanted (e.g. mouseless) configuration.
Thats not necessarily a problem particularly with USB mice.
Thus mechanical KVM switches are unsuitable for controlling machines which may reboot automatically e.g. after a power
failure.
And not just those, also when the user doesnt want to fart around waiting
for each PC to fully boot with the KVM switched to each PC as it boots.
Most active (electronic) KVM devices
And there arent any that arent that anymore.
provide peripheral emulation, sending signals to the computers that are not currently selected to simulate a keyboard,
mouse and monitor being connected. These are used to control machines which may reboot in unattended operation.
In fact they are all like that now.
Peripheral emulation services embedded in the hardware also provides continuous support where computers require
constant communication with the peripherals.
Hardly any of them do.
J
Jonathan Mars
DevilsPGD wrote:
I solved it for much less money than a new KVM. My monitor has VGA and
DVI inputs so just connect computers directly to the monitor and use the
KVM purely for mouse/keyboard and a printer. My KVM is only VGA and
wanted one computer to use DVI so I could have centered timings for non
16:9 games. DVI KVM's cost too much but when their price is reasonable
I will get one.
That would be because the computer cannot query the monitor's
capabilities, so it assumes the worst.
A better KVM seems to handle this nicely, providing accurate monitor
capabilities, or at least providing it's own capability set.
I solved it for much less money than a new KVM. My monitor has VGA and
DVI inputs so just connect computers directly to the monitor and use the
KVM purely for mouse/keyboard and a printer. My KVM is only VGA and
wanted one computer to use DVI so I could have centered timings for non
16:9 games. DVI KVM's cost too much but when their price is reasonable
I will get one.
J
Jonathan Mars
Rod said:Nope, just plain wrong.
Nope, you are wrong if we are talking USB KVM whicvh is what I was
asking about in the first place. You are talking PS2 KVM when I have USB
KVM. I can hear the USB devices being disconnected from the PC because
windows plays a sound file when they disconnect. If they were being
emulated then they would never get the disconnect sound. Read DevilsPGD
post below because he says the same thing. USB KVM's hot swap the
devices and do not emulate that they are still connected to the PC when
they are not.
D
DevilsPGD
In message <[email protected]> "Rod Speed"
Sadly, that isn't really true. The pass mechanical ones are mostly
gone, but that doesn't make the situation any better, the current
"cheapo" generation are still passive, they're just an electronic switch
between the various inputs rather then a mechanical switch.
An active KVM emulates a valid keyboard, mouse and monitor at all times,
the passive ones just pass through the connected keyboard/mouse/monitor
signaling when the appropriate port is selected.
None are that primitive anymore and havent been for a hell of a long time now.
Sadly, that isn't really true. The pass mechanical ones are mostly
gone, but that doesn't make the situation any better, the current
"cheapo" generation are still passive, they're just an electronic switch
between the various inputs rather then a mechanical switch.
An active KVM emulates a valid keyboard, mouse and monitor at all times,
the passive ones just pass through the connected keyboard/mouse/monitor
signaling when the appropriate port is selected.
R
Rod Speed
Jonathan Mars said:Rod Speed wrote
Nope, you are wrong if we are talking USB KVM whicvh is what I was asking about in the first place.
It isnt even possible for USB KVMs to be entirely passive.
You are talking PS2 KVM
Wrong.
when I have USB KVM.
And that is what I was talking about.
I can hear the USB devices being disconnected from the PC
because windows plays a sound file when they disconnect.
That does NOT mean that the KVM is mechanically switch, it JUST means that the simulated
mouse and keyboard dont have the same USB device details as the physical mouse and keyboard.
If they were being emulated then they would never get the disconnect sound.
Wrong, as always.
Read DevilsPGD post below because he says the same thing.
No he doesnt.
USB KVM's hot swap the devices and do not emulate that they are still connected to the PC when they are not.
Have fun explaining how come you can boot PCs which arent currently selected
with the KVM without the PC whining about the lack of a keyboard and mouse.
THAT proves that the keyboard and mouse MUST be emulated and arent mechanically switched.
They cant be mechanically switched when they can be switched using keystrokes either.
You're just plain wrong and dont understand the basics.
R
Rod Speed
Sadly, that isn't really true. The pass mechanical ones are mostly
gone, but that doesn't make the situation any better, the current
"cheapo" generation are still passive, they're just an electronic
switch between the various inputs rather then a mechanical switch.
You're just plain wrong. If what you said was correct, you couldnt boot
PCs that dont have the physical keyboard and mouse switched to them
without the PC whining about the lack of a keyboard and mouse. They
must be emulated by the KVM if they can be booted without the KVM
being switched to the PC while its booting.
An active KVM emulates a valid keyboard, mouse and monitor
at all times, the passive ones just pass through the connected
keyboard/mouse/monitor signaling when the appropriate port is selected.
And they are all like that now. There arent any that just switch the
physical mouse and keyboard to the one PC. Essentially because
its so trivial to emulate the keyboard and mouse enough so that the
PC doesnt whine about not having a keyboard and mouse connected.
J
Jonathan Mars
DevilsPGD said:If it's less then $20 of molded plastic and doesn't have an external
power source then it almost definitely is a passive type like the old
mechanical ones of yestercentury.
I've never seen a KVM with an external power source. I won't spend over
fifty bucks for a 2 PC KVM. I see the ones with DVI that I would like to
buy are well over one hundred bucks.
J
Jonathan Mars
Rod said:Have fun explaining how come you can boot PCs which arent currently selected
with the KVM without the PC whining about the lack of a keyboard and mouse.
Since when is a mouse and keyboard a requirement to boot an OS?
You're just plain wrong and dont understand the basics.
And you are a rude person with no friends.
J
Jonathan Mars
DevilsPGD said:An active KVM emulates a valid keyboard, mouse and monitor at all times,
the passive ones just pass through the connected keyboard/mouse/monitor
signaling when the appropriate port is selected.
Yea, and that's what both of my cheapish KVMs do. Rude-boy Rod is wrong,
once again.
R
Rod Speed
Jonathan Mars said:Rod Speed wrote
Since when is a mouse and keyboard a requirement to boot an OS?
Its not a requirement, but plenty of OSs will whine about the lack of a
keyboard and mouse and quite a few bios do too with the keyboard.
And you are a rude person with no friends.
You're lying now. I just rubbed your nose in the basics. You get to like that or lump it.