how safe is it to reconnect cables while machine is running ?

[CJT]

Greg Lewin wrote:
Hi, In general, we are given dire warnings not to disconnect/reconnect cables of all sorts while the machine is running. How critical is this with e.g. kb cables, mouse cables, or video cables? Recently I saw some people swapping video cables (to an external screen that is) on a mac laptop while running, apparently without any damage. It would be very handy to be able to swap screens on the fly. In general, is this safe, or something that is a bit risky? I have also been getting odd dropouts on my keyboard, and would like to be able to unplug/plug it in again when this happens. I've done this a couple of times successfully but feel uneasy about it. Thanks, Greg

my 2 cents:

serial mouse -- no problem

KB & PS/2 mouse -- I wouldn't (especially KB, which does its own POST)

same monitor that was connected at boot -- probably ok

different monitor -- unless you know it will work with the currently
configured settings, I wouldn't

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[JK]

Greg Lewin wrote:
Hi, In general, we are given dire warnings not to disconnect/reconnect cables of all sorts while the machine is running.

You can safely do it with USB. Don't do it with anything else.
How critical is this with e.g. kb cables, mouse cables, or video cables? Recently I saw some people swapping video cables (to an external screen that is) on a mac laptop while running, apparently without any damage. It would be very handy to be able to swap screens on the fly. In general, is this safe, or something that is a bit risky? I have also been getting odd dropouts on my keyboard, and would like to be able to unplug/plug it in again when this happens. I've done this a couple of times successfully but feel uneasy about it. Thanks, Greg

[Greg]

I was the PC guy in my office and I hot plugged stuff all the time. IDE drives
won't be recognized until you reboot so there is not much reason to do it but I
used to have a bunch of 320m SCSI drives I swapped around like diskettes.
In fact the "hot plug tray" in a RS6000 was nothing but a centronics plug and a
power plug on a regular SCSI bus.
Some machines will take a hot plugged keyboard others won't. They just don't
issue the reset necessary to initialize the processor in the keyboard. Just be
sure you don't carry a static charge and be prepared for the software to puke.
I always heard the dire warnings but I seldom ever saw the problems.
BTW most cheap KVM switches are nothing but that ... a switch with a bunch of
poles.
You are "hot plugging".

[Charles Howse]

Previously Greg Lewin <greglewin@ednet.co.uk> wrote: Hi,
In general, we are given dire warnings not to disconnect/reconnect cables of all sorts while the machine is running. How critical is this with e.g. kb cables, mouse cables, or video cables? Recently I saw some people swapping video cables (to an external screen that is) on a mac laptop while running, apparently without any damage. It would be very handy to be able to swap screens on the fly. In general, is this safe, or something that is a bit risky?

No problem at all here, as long as (if it is a crt) the new
monitor can stand the screen refresh rate.
I have also been getting odd dropouts on my keyboard, and would like to be able to unplug/plug it in again when this happens.

Don't do this, unless it is USB. Non-USB keyboards are not designed to
be hot-plugged. They need some initialisation and may not work
correctly when hot-plugged. In theory, if you can live with things
like incorrect repeat rate, you can hot-plug a PS/2 keyboard, but you
have to be careful and fast at the same time. However you can only do
this because modern keyboard processors have very robust I/O. You
can still blow up your keyboard processor and possibly shorten
out the PS/2 port (and damage it permanently) if you do this
with a keyboard with a substandard keyboard processor.
I've done this a couple of times successfully but feel uneasy about it.

Trust this feeling.

Arno
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[Greg Lewin]

Hi,

In general, we are given dire warnings not to disconnect/reconnect
cables of all sorts while the machine is running.

How critical is this with e.g. kb cables, mouse cables, or video cables?

Recently I saw some people swapping video cables (to an external screen
that is) on a mac laptop while running, apparently without any damage.

It would be very handy to be able to swap screens on the fly.

In general, is this safe, or something that is a bit risky?

I have also been getting odd dropouts on my keyboard, and would like to
be able to unplug/plug it in again when this happens.

I've done this a couple of times successfully but feel uneasy about it.

Thanks,

Greg

[Greg Lewin]

Thanks for the tips.

Greg