driving a computer bus

[glenpa]

Hi,

I am working on a KVM switch and I am stuck to the part where I must drive different busses.

I have the main components (video, mouse, keyb) and want to drive their signals towards different computers depending on my selection.

I have 4 signals, 1 for each computer and this signal must drive the components bus to the concerned computer.

My question is, is it as simple as using multiple octal bus driver ICs or must I considerate anyhing else?

 

[Lewish]

Been there, done this exercise. By the time you buy RF quality parts for the video, it is cheaper to buy a commercial unit. They are only about $100.

But to try to answer your question - the video is a 75 ohm signal. That means that the parts to route the video must all be 75 ohm. And, you must provide a 75 ohm termination to the unused video boards. Failure to follow this guide line will result is images on your screen which look like ghosts. Colors will be off.

As to the keyboard and mouse, if they are PS/2 style, you need to provide something that looks like a keyboard and mouse to the computers that aren't selected. Most operating systems, Windoze particularly, get upset if their keyboard or mouse disappears.

 

[glenpa]

Thanks for your advice Lewish!

I haven't of that video signal detail. If I understand for the PS/2 devices that must be supplied on non connected machine, I can simply suply some mouse and keyb circuit to these connections to satisfy Windows.

I am aware of the cheap prices but I just want to try making one. Hard headed sometimes :-> .

Glen P.A.