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Build & Win An ELF at VCF Midwest

Celebrate the 40th anniversary of the COSMAC ELF computer by participating in a build of one at the Vintage Computer Festival Midwest --- and possibly taking it home with you! The idea is simple: drop by our booth at the festival and wire-wrap a connection or two (we’ll have the parts and tools and will show you how). Everyone who participates will get a raffle ticket, and the newly built ELF will then be raffled off. Bring your favorite kid along and give them a taste of microcomputing’s early days.

The design and build is very similar to the original ELF, but with a few improvements to lower its power requirements and provide for easy expansion. The design is primarily the work of Lee Hart (creator of the tiny, popular Membership Card computers) and Josh Bensadon, with parts donated by several community members.

The COSMAC ELF Turns 40

Illustration of a COSMAC ELF computer with a golden number "40" above it.


In August of 1976 the cover of Popular Electronics featured a peculiar little device built on a piece of perfboard with a 2-digit hexadecimal display, an LED, 11 toggle switches and a pushbutton. The text read “THE COSMAC ‘ELF’ --- A MICROCOMPUTER TRAINER THAT’S POWERFUL, EXPANDABLE AND COSTS AS LITTLE AS $80.” The large chip in the center of the perfboard was RCA’s CDP1802 COSMAC microprocessor.

The chip’s inventor and by far its greatest evangelist was Joseph Weisbecker, who wrote the article to introduce the hobbyist community to this simple CMOS microprocessor. The machine featured in the article was minimal: 256 bytes of RAM (less characters than two tweets on Twitter!) and no ROM. Yet the machine could be programmed, opcode by opcode, to play simple games, play music (if one wired up a speaker), or expanded to control external devices. For many, this hand-wired, low-cost machine was their first computer, and an entry into the world of microcomputing. There seems little doubt it helped launch more than a few engineering careers.

In Weisbecker’s view, everyone could eventually own and perhaps even understand and program their own personal computer, for productivity and entertainment. While he’d write future articles that expanded the ELF with such things as video and a photocell “light pen,” the beginning was about as simple as a computer could be.

40 years later, this is still a great little machine to build, play with, and learn on. Drop by the Vintage Computer Festival Midwest on September 10-11 to celebrate the anniversary with us!

Browse our Gallery to find builds of the original COSMAC ELF as well as the many creative home-built machines inspired by it.

© Dave Ruske 2001-2017, except where noted