My Early Days and the 1802 -------------------------- Date: Tue Jul 27, 2004 In my case, my first computer was a "Geniac". This was basically a set of twelve big home-made rotary switches (masonite disks with screws for the contacts). You wired these switches up to produce the AND, OR, and NOT functions basic to all digital logic. A battery provided power, and light bulbs were the output device (and told the operator when to rotate the switch disks. As you say, this simple device gave me the "Aha!" moments to understand how digital logic and computers work. Mar 17 2005 The Mark-8 was my first microcomputer system. It was a horrible design, and I just could NOT get it to work! I finally gave up when the RCA rep loaned me a Microtutor. Then the PopTronics Elf article came out, and I was hooked! I sold the Mark-8 to some other unsuspecting soul, and never looked back. :-) ... It is hard for people today to appreciate just how hugely complicated these early systems [like the Mark-8] were. There was no sense of finesse -- everything was brute force. Compared to this, the 1802 and the Elf were absolutely unbelievably simple. It was as if someone opened the hood of their car, and instead of the normal engine with its thousands of intricate expensive parts, there was nothing but a squirrel running on a wheel. And yet it worked! In this modern age, when everyone assumes that solutions *have* to be complicated, it's great to have counterexamples to show that ingenuity and intelligence can provide a better answer. Sept 26 2005 My [first] Elf used 4.5" x 6.5" perfboard with 22-pin double-sided edge connectors. This is a standard size that Radio Shack carries even today. RCA used that same connector on all their 1802 systems. Their schematics are all published, so if you use their bus pinouts you can use any of their "Microboards". My first CPU board had just the 1802 and its clock and reset circuit. Very empty board; just a few chips. My memory board had two bytewise memory chips, and a few decoder chips. Also very simple and empty. My front panel board had all the switches and LEDs you see on an Elf. It was fairly full because all those switches and LEDs take a lot of room, plus the were half a dozen chips to drive them. My I/O board had a current-loop "bit banger" serial interface for an old Baudot mechanical teletype. That was my keyboard and line printer. This board also had a audio cassette interface. This board was also mostly empty. As I learned, I built better boards for each of these. I could add the new boards and test them one at a time. It worked out very well, and let me develop the first TMSI BASYS board, which was the more usual "single board computer". Sep 14, 2004 7:32 am Subject: Re: [cosmacelf] 1802 robots (was Re: 1802 Logo) [In the 1970's], there were a lot of 1802-based robots because it was the only CPU you could get that was suitable to run off batteries. A friend of mine, Jeff Duntemann, built one he named "Cosmo". He wrote it all up in a great self-published booklet he called "Captain Cosmo's Whizbang." I still have a copy, and it's on my list of things to get on the web. Anyway, Cosmo's brain was an RCA VIP. The video output drove a little TV set to produce Cosmo's face. It had a huge grin, googly eyes that rolled around, could stick out its tongue, laugh, scowl, etc. at you. Very inventive! A little 12v wheelchair battery provided power. Two windshield wiper motors, side-by-side with a wheel on each, and a chair castor provided basic motivation. Jeff built a robot arm that worked pretty well, until Cosmo broke it showing off crushing beer cans. Cosmo was actually remote-controlled by Jeff via a walkie-talkie. But lots of fun at parties :-) He inspired me to build my own robot. I put a BASYS board in a 3"x5"x7" minibox. 4 nicad D-cells inside for power. Two stepper motors were mounted in the center of each side, with a wheel on each. The robot balanced on these two wheels, since all the weight was below the axles. There was also a front and rear "toe" switch, that were normally held depressed by the table but would open if the front or rear went over the edge. There was also a fixed pair of "fingers", also with microswitches that closed if the fingers bumped something. The bump switches tied to the 1802 EF1-3 lines, and there was a loudspeaker tied to Q. Finally, it had an RS-232 port using EF4 and Q for communications. I named it ITSABOX (It's a box turtle robot, get it? :-) as it was inspired by the Logo turtle robots. Itsabox was programmed in 8TH, which was my variant of the FORTH language. It had all the basic primitives to move forward, back, turn left and right, play music, and sense the bump switches. TMSI had a booth at the West Coast Computer Faire in 1982. So, I wrote a quickie program that told Itsabox to march forward and sing a little song until it found an obstacle or the edge of the table. If an obstacle, it said "ooops!" and turned. If it found the edge of the table, it said "oh-oh", backed up, then turned. It then continued on its merry way. As it turned out, our booth was right across from Heathkit's. And, this was the place that they introduced their "Hero" robot. It was big, complex, and impressive! But, they quickly discovered it was also deaf, dumb, blind, and stupid. After smashing itself into walls, bonking people in the head, and driving off the table a couple times in the first hour, it was destroyed and spent the rest of the show as a stationary exhibit. Meanwhile, Itsabox kept marching back and forth across our table, singing its silly song, never once marching off the table or pushing anyone's drink onto the floor. We were *flooded* with requests to purchase it, but we had to say, "No, it's just a one-off prototype; it shows what you can do with our 1802 board." 20/20 hindsight is wonderful. If only we'd known that people wanted robots, we'd have made them. Alas... Mar 3, 2006 My VIP [became] the brains of a robot I built long ago. I'd be hard pressed to find a modern replacement that was as easy to program, as low in power, and as simple to interface to motors and sensors. I have 1802's in a couple other gadgets I built; an az-el antenna rotator for ham radio, and an EPROM programmer. But these don't get used much any more. Mostly, I like to tinker. I can throw together an 1802 system from raw chips in a couple evenings, with no help from a PC as a 'crutch'. That's impossible with anything modern.