Use an old Pc in place of micro controller.

[bottomslogger]

Dear Sirs,
   
   I am new to this site, but have played with machines and computers for awhile... I have accumulated a vast hoard of old and fuctional computers. I am very interested in using them to control other stuff. Robotics is to narrow a definition. Why not put my outside lightes on a circuit and put it under the control of a computer? Don't get me wrong I AM very interested in robots.
   So I guess what I am asking is:
1) does anyone know how to feed an input into a computer... If so the more info the better. I was hoping that there would be a way to hook up a multiplexer to an input ( somewhere)
2) Does anyone know how to get an output out of a computer... If you can only send in input, it would be limited; would it not?
   Any information that you can provide, or sources of info are welcome.

   Thank you for your time any trouble.
             Bottomslogger

[paulstreats]

Most people use a microcontroller as a midway point. So the computer connects to the microcontroller through a serial port.

There are some usbl i/o interface boards that you can use aswell like these:
http://www.maplin.co.uk/module.aspx?ModuleNo=42857&doy=12m7

[JesseWelling]

You might check out Phidgets if you timing requirements are not to demanding.

[Soeren]

Hi,

I have accumulated a vast hoard of old and fuctional computers. I am very interested in using them to control other stuff.[...] So I guess what I am asking is:
1) does anyone know how to feed an input into a computer... If so the more info the better. I was hoping that there would be a way to hook up a multiplexer to an input ( somewhere)
2) Does anyone know how to get an output out of a computer...

Old computers usually means no USB, but a parallel and serial ports, which is easy (and cheap) to interface.
If you need lots of inputs or outputs, you can interface them cheaply by using serial to parallel and parallel to serial shift registers, as long as you can live with the reduced speed (you need to clock each bit through).

No reason I start a tutorial on the subject here, go to http://www.beyondlogic.org/ and start reading
(Lots of stuff on USB and ethernet as well, so might be usefull to a lot of this sites users).