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Computer Science Colloquium: A Relay-Based Computer: Computing Before Electronics
Monday, April 24, 2006 - 12:00pm to Monday, April 24, 2006 - 1:00pm

The Department of Computer Science at PSU's Maseeh College of Engineering and Computer Science presents as part of the Computer Science Colloquium Series, A Relay-Based Computer: Computing Before Electronics.

Title: "A Relay-Based Computer: Computing Before Electronics"

Speaker: Harry H. Porter, Ph.D., Adjunct Faculty, Portland State Univeristy

Date:April 24, 2006

Time: 12:00 - 1:00 p.m.

Location: FAB 310-18 , 1900 Building, 1900 SW Fourth Avenue, Portland, Oregon 97201 (map)

This series is free and open to the public. For further information, contact the Department of Computer Science, (503) 725-2416 or

Before VLSI, before TTL, before transistors, even before vacuum tubes, computers were made out of electro-mechanical relays. This talk will describe a recently constructed, fully-functional, stored- program computer built using 1940's technology. Computers have gotten rather complex lately, but the core concepts of a modern CPU (registers, busses, ALU, program sequencing, instruction decoding) can all be achieved with more simplicity than you might guess. The architecture includes instructions for register-to-register movement, logical and arithmetic computation, conditional branching, call and return and memory load and store. By stripping away all the complexities introduced solely to achieve performance, we can see what truly constitutes the von Neumann Architecture.

The computer will be on display and will be demonstrated. For photos, check out .

Speaker Biography
Dr. Porter is an adjunct faculty at Portland State University with active interests in many research areas. Most recently he created the BLITZ system, a software framework for the support of kernel research and education. The BLITZ system consists of a RISC processor architecture, along with a virtual machine emulator and associated software components. The BLITZ system is specifically tailored for students doing OS kernel development.