Lok’s ELF 2000 Gallery

9 ELF2k final hex cover

Lok thought the Spare Time Gizmos ELF 2000 was a great little computer, but the kits were no longer available. Undaunted, he used the schematics and firmware to build his own from scratch, handwiring it as many did the much simpler original ELF. Then Lok took the project to the next level, crafting an eye-catching maple cabinet for it and topping it off with a plastic dust cover.

For a full set of photos and the story behind Lok’s creation, check out its gallery page.

Thanks for the contribution, Lok!

The Games of Joseph Weisbecker

Photo of Joseph Weisbecker's "Bits and Spaces" game prototype; photo courtesy of The College of New Jersey, reproduced here by permission.

The inventor of the COSMAC architecture, Joseph Weisbecker, had a seemingly boundless enthusiasm for computing. It showed not only in the microprocessor line he created and promoted for RCA, but in the variety of logic puzzles and games he designed to teach and entertain. These are now showcased in a new exhibition at The College of New Jersey, Playing With Innovation: The Games of Joseph Weisbecker.” 

According to curator Florencia Pierri, who organized the exhibition, “it's centered around the paper-and-plastic games that Weisbecker made when he wasn't busy working at RCA. The exhibit focuses on the computer-centric games he and others created, and their place in the history of computing.”

While many of us have seen Think-A-Dot before, some of these games exist only as prototypes and were never commercially available. The online exhibit is nicely organized; click on any game’s picture to get more details on the artifact. The exhibit concludes with some of Weisbecker’s early computer prototypes, including an 1801-based FRED 2 that Herb Johnson has thoroughly detailed on his website. (Herb is also acknowledged as a contributor to this exhibition.)

If you’re in the New Jersey area and would like to visit the exhibition in person, you can find details here.

High Quality OCR Questdata


Steve Brune has been busy rescanning Questdata newsletters, with most pages from his own originals, and has made them available here. The new versions look great at 600 DPI with searchable OCR text, but the old versions are still available as well for those who need much smaller, faster downloads.

Thanks for the contribution, Steve!

VCF Midwest 12

The Vintage Computer Festival Midwest continues until 4 p.m. this afternoon, so if you’re in the Chicago area there’s just a few more hours to get in on the fun! Take plenty of photos and send links via the Facebook page so those of us who couldn’t make it can share a sliver of the experience. Have a great time, everyone!

Update September 16, 2017: Links to photos of VCF Midwest are now up on their website.

Boyd Calculator on Hackaday

Al Williams wrote up a nice little article for Hackaday about work he, Bill Rowe, and other forum members have been doing to repurpose some old Boyd calculators based on RCA’s CDP1805. Check it out here!

COSMAC ELF Manual & Build Details

COSMAC ELF Users Manual

After creating a beautiful replica of the original COSMAC ELF, Paul Schmidt documented the heck out of it and made his hard work available for others to learn from. If you want to build one of the simplest computers of the mid-1970s, this is definitely the place to start!

Paul granted permission for his work to be made available here. You can find links on the Books & Papers page for the full ZIP file containing the manual, schematic, parts list and templates, or you can just browse the PDF manual to learn more about the machine.

Build one of your own, then drop by the forum and share your experience!

FIG-Forth Manual & Upcoming Events


I’d thought about putting up an April Fool’s page of some sort, but I’ve had so little time for the site lately I was afraid it would stay in place until Halloween --- my “Happy Holidays” has been the top News item here for entirely too long. So instead I found a few minutes to pull a couple lingering tasks from the backlog, no fooling.

New to the Books & Papers area are links to Dr. C-H Ting’s FIG-Forth manual. Juergen Pintaske worked with the author to make this available in Amazon’s Kindle format for a modest fee. You can search for “Juergen Pintaske” on your local Amazon website to find other Forth related works Juergen has helped resurrect as well.

Also (finally!) you may notice that the Upcoming Events in the links area of each page have been updated for 2017’s Vintage Computer Festivals. VCF East is going on right now in Wall, New Jersey! If you see anything COSMAC related, drop by the forum and let us know all about it!

For fans of the original ELF, there’s some terrific content from Paul Schmidt that’ll be be hosted here soon.

Happy Holidays!

We wish you, your families, and your Elves all the best this holiday season! Let’s build something clever in 2017!


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 2001-2018, except where noted