Altaid 8800

Summary

Altaid 8800 A Classic 8080 Microcomputer in an Altoids Tin The January 1975 issue of Popular Electronics magazine had a breakthrough project on the cover. The Altair 8800 -- World's First Microcomputer Kit to Rival Commercial Models". (Click on the link to read the original article.) One thing that struck me about microcomputers back then was how big they were. Big impressive boxes (with big impressive marketing claims) seemed to be the norm -- even when the boxes (and marketing claims) were mostly full of hot air. Conventional wisdom said that they had to be big, due to the limitations of the technology at the time. But was that really true? We had pocket calculators before the Altair. They are all microcomputers, too. The HP-35 scientific calculator came out 3 years before the Altair, and had considerably more computing power at a lower price. And... it fit in your shirt pocket! So I got to wondering... Could we have built an 8080 microcomputer, like the famous Altair 8800, but in a pocket-sized package? No "wizard behind the curtain" modern chips to make it work. It had to be built with vintage parts and through-hole techniques; just as it would have been back then. It must be user programmable; not simply running a fixed program like the HP-35. And, it's got to have a real front panel, like the Altair with its classic switches and blinking lights. I set out to try. I had previously built a reproduction of the August 1976 Popular Electronics "COSMAC Elf microcomputer" in an Altoids tin. I called it the 1802 Membership Card. It used the RCA 1802 microprocessor, which is a natural for battery operation. That project turned out very well. I made it available in kit form, and hundreds have been sold (click the link for details). But the 8080 was a much harder nut to crack. It isn't quite a complete CPU by itself; it needed several support chips to finish the job. It also needed three supply voltages; +5v, +12v, and -5v. That made it tough to power it from a single-vo...