Abstract: Hardware Interfacing Using Parallel Port Programming is designed to control electrical appliances using computer printer port. The electrical appliances are controlled by using software through an interfacing circuit. The software used in this is TURBO –C. A windows based program is used to control eight LEDs, through an interfacing circuit, by using computer printer port. The base address used is LTP1 (0378 H). The program accepts input signal from the keyboard, decodes the keyboard hit and accordingly send signal to the corresponding pins of the printer port which in turn controls the LEDs. It is further extended to the automatic control i.e. in random or sequential order of the LEDs. The LEDs will be controlled automatically according to some delays provided in the program. The purpose of this work is to reduce human effort in controlling large number of switches as in stadiums, buildings, apartments etc. This effort can also be extended to controlling up to 256 electrical switches by the use of proper interfacing circuits. By proper implementation, 256 electrical switches can be controlled using only eight keys from the keyboard.