[RTTY] Question on KVM switches

[Ekki Plicht (DF4OR)]

On Tuesday 08 January 2008, Bill Turner wrote:
> I could use some advice on the subject of KVM switches (keyboard,
> video, mouse).
>
> I have one keyboard, monitor and mouse I want to switch between two
> computers. I have been browsing Newegg's KVM switches and I see they
> have hundreds of them ranging in price from about$ 20 up to several
> hundreds of dollars. I don't think I need any of the real fancy ones,
> but I have some questions on the simpler ones.
>
> For instance, what is "remote switching". Several advertise that but
> they don't say what it is or how it works. 

You can remotely tell the switch which PC to connect to your K/V/M. For 
example by an electrical signal, or by special keyboard commands. Others 
require you push a button on the device itself to select the (next) other 
computer.


> Also, some advertise 
> "scanning every ten seconds" or "every four seconds" or some such.
> What is that all about?

Those scan for a video signal on each input and switch to the first one it 
discovers, in case you turn both computers on. 

> One even advertised being able to switch by pressing the scroll lock
> key twice. That sounded good. but now, of course, I cant find the same
> ad a second time. Senility strikes again. :-)

That sounds like the one I have got. Hit ScrollLock twice, hit key up or down 
to select the next computer. Very convenient.

Some general tips:
Long and cheap cables can severely deterioate the VGA video signal (analog). 
The signal gets distorted, resulting in visible shadows on strong vertical 
contrast lines (edges of windows etc.), fuzzy, hard to read letters etc.

If you use analog signals try to get very high quality cables with little 
attenuation, high bandwidth, just as short as necessary. Use DVI (digital) 
signals if you can and if your computers and displays support it. They don't 
suffer from this problem. 

Insist that you can return the device if it does not work satisfactorily. I 
had one which gobbled up keystrokes, for example when hitting Ctrl+Something, 
it didn't get the Ctrl, it missed one out of three. Bad when your logging 
program requires Ctrl-W for storing the QSO or so. The support guy suggested 
I should type more slowly :-), I returned the unit.

Try to get one which does not need an additional wall wart. Most do without, 
drawing power from the keyboard ports of the attached computers.

Try to get one which does not need special drivers for your operating system. 
The one I got (with remote control by hitting ScrollLock twice) works without 
drivers under Linux and Windows.

73,
Ekki, DF4OR