Relay Computer 2 (RC-2)

While still an undergraduate student at Rice University, Jon Stanley built this relay computer in 2007 as an effort to better understand computer processors and to demonstrate that silicon was not magic. The Project was inspired by Harry Porter's relay computer that consisted of 415 relays encased in four large modules.

This relay computer was built on a budget of under $200 and consists of approximately 280 relays that operate on 24 volts. The architecture was designed with an 8-bit data bus and 16-bit address to address up to 64KB of memory space. There are three general purpose registers and a total of 24 instructions for this computer that include arithmetic, logic, and basic memory and register operations. The clock speed runs at a couple cycles per second and executes roughly one instruction every two seconds. In comparison, modern day computer processors run at least a billion times the speed of this relay computer.

[Note] Harry Porter with his Relay Computer

General Specifications:

• Data Bus (8 bits)
• Address Bus (16-bits)
• All relays are the identical part (Four-Pole-Double-Throw, 12 Volts)
• 415 Relays
• 111 Switches
• 350 LEDs
• Max Power Consumption: Estimated 12 Amps @ 13.5 Volts (160 Watts)