By Stephen Cass

Regular readers of this column may have noticed that I have a fondness for  new takes on old technologies. So you won’t be surprised that when I came across Lee Hart’s Membership Card kit, I leapt at the chance to build it. The Membership Card is a modern version of the 1976 Cosmac Elf.The Elf was an influential early microcomputer built around RCA’s CDP1802 processor. What may be more surprising is that the Membership Card might be just the ticket for modern makers looking to build microcontroller-based devices that can run for a year on a few AA batteries.

The original Elf dates from the heroic age of personal micros, a time before QWERTY keyboards and bitmapped displays became standard and made us all soft. Input was via a set of toggle switches, hand-setting each bit in a byte. You wrote programs in pure machine code. You read the output via a two-digit LED display capable of showing one hexadecimal digit apiece, plus one additional so-called Q LED. The Membership Card is even more severe on the output front than the original: “Numeric” output is via a row of eight LEDs that display a byte in binary. You can’t get closer to raw computation withoutan erasable marker and a really long piece of tape.   ….[Read more]