You can start by learning to use the parallel port and serial port. MIDI-Game port also has enough to help you start, learn computer interfacing at home. Try a small easy experiment RS-232 Powered Temperature Sensor.
This can get you started too. The few examples above show an instrumentation - Logic Analyzer 'Like' interface and a relay-display driver circuit. They are examples i tried for students to try out and learn.
Control Interface to PC Ports.
- Simple Printer Port Interface, Input-Output.
- Test Circuit for Logic Analyzer software.
- Printer Port, 256 Relays - 16K Dot Matrix.
- Byte Blaster Clone for use in Quartus.