• Sequence control of 8 LEDs through 8255 port
  • Control of 2 relays
  • Operating a 7-segment display
  • Switch state input through 8255 port
  • SID/SOD Operation


This unit has been designed to train the students to handle basic input-output operations of the 8085 microprocessor through 8255 ports. The power supply, drivers and other hardware are prewired resulting in a greater reliability of operation. The students are expected to enter a few suggested programs and also to develop their own programs for a variety of input-output operations, which include :

  • Light the 8 LEDs in a cycle, in binary sequence, as a bar graph display etc.
  • Operate the 2 relays with software controlled timing
  • Operate the 7-segment display through segment control
  • Sense the state of the 4-switches as input and send out suitable signals to various output devices.
  • Study of SID/SOD

The system comprises of a main unit and a µp kit, connected through a flat cable. The main unit houses all the I/O devices, viz. LED’s, relays, 7-segment display, switches and their drivers/ interfacing circuits. In addition the status of the relays and switches are displayed with the help of lamps mounted on the panel.

Schematic Diagram



12262 Goleta Avenue, Suite 121, Saratoga CA 95070 Phone: +1 408-230-9381 Fax: +1 408-898-4863, Email: info@svslabs.com
© 2003 SVSLabs. All rights reserved.