Never worked, but fun while it lasted.

System History/Future

This machine was my brave leap into trying to rescue a computer from a hopelessly terrible condition. It originally belonged to a friend of my grandfathers. It was a fascinating machine, in that it had the most familiar though unique design. It was also a machine that I could not save. The story is below. I recieved this machine from my grandfather, after I got desperate for a new machine to play with and pestered him long enough (sorry grandpa!). He was going to give me the machine anyway, so I just, ahem, accellerated the process. Unfortunately when I recieved it, it had been in my grandfathers storage area, and exposed to many various things including moisture, dust, and spiders. After getting it home and putting it in my room, much to the dismay of my mother, the first thing I did was, against the recommendations of many wise people, plugged it in and turned it on. Of course, nothing happened. The only sign of life was the noisy hum of the half-neglected case fan on the back of the disk drive unit. Well, a running fan is a far cry from a running machine. Needless to say the situation looked bad. Here I was with two large boxes and a monitor equal in size, and the only thing that seemed to work was the fan on the back on the disk drive! Obviously the first thing I had to do was to give the computer a good cleaning. What fun! The first thing I cleaned was the disk drive unit, because it required the most work just to get it outside where I could dust it out. After removing the two 8" disks (which I'm sure were ruined by moisture) and opening the case, I stared in shock at the amount of metal inside. Needless to say these will not fit in a standard drive bay. The disk drive is rather un-interesting. It's just a larger version of the drives you use all the time. Drive motor, read/write arm, etc, except on a larger scale. After cleaning the drives and putting them back in the case, I proceeded to the CPU, which was the more interesting (and lighter) second box. This is where I found out just what this machine was. The first thing I looked for was the motherboard. After pulling the motherboard off of the back-plane I realized what I had just found, a KIM-1 computer in fairly good condition. The KIM-1's, made by Commodore and predating the Commodore 64, were essentially just a motherboard with a surface mounted hex-keypad and LED display for input/output. All you need, if you are daring enough to try operating a computer purely in hex, is a power supply for the KIM-1. But the KIM-1 was a trojan horse. That is, if you could interface it with an S-100 bus (which it was capable of doing), you could greatly expand the KIM-1's capabilities beyond that of a processor and keypad on a motherboard. That is exactly what the guy who built this computer did. After pulling the KIM-1 off of the KIM-1 bus board, I proceeded to the next card. I knew this card was the floppy controller because I had seen the chips it contained before on my TRS-80, and the disk drive interfaced directly with it (dead giveaway). Like the motherboard, it was in great condition, so all it needed was a good dusting. The RAM boards came next. I laughed when I saw them. This machine probably had at least 32k from all these expansion boards, and boards of similar size today could probably hold gigabytes of RAM on their surface-lands. Like the motherboard and FC card, these cards were in particularly good condition. Next came a particularly interesting card. The interesting thing about it was the fact that it was a wire-wrapped board. The person who built this machine built his I/O board from scratch! After pulling all the cards and cleaning them off, I proceeded to clean the KIM-1 bus board and the power supply. After that I checked all the chips on the boards to make sure they were seated right, checked the wire wrapping on the I/O board to make sure nothing was loose, and put all the boards back in. Next came the dumb-terminal (monitor). Boy was this a challenge. When I first took it apart I found a dusty mess. It came apart easy, but what wasn't easy was getting the mainboard cleaned. There was about a decade and a half of dust on it. After cleaning the mainboard I proceeded to the power supply/host interface, which was inside the base stand of the terminal. While cleaning the power supply I managed to look up just in time to see a brown recluse spider staring at me. Now, one thing about brown recluse spiders is that it's not a good idea to mess with them, they are poisonous. After battling the recluse with a flyswatter, and winning (that thing didn't know what hit it!), I put the then-clean dumb-terminal back together. The keyboard was easy and came clean in about ten minutes. After all the cleaning work, I once again hooked the machine back up, plugged it in, switched it on, and the fan on the disk drive started wirring, though quieter. After sitting for a second in amazement, trying to figure out what was going on, cycling the power several times and such, I decided that I was not ready to throw in the towel yet. From what I think I know about systems like this, is that when it starts up, unlike systems of the present, you only get a blinking cursor on the terminal. You have to manually tell the CPU, in hex/binary/etc, where the bootstrap (boot) routine is in memory. Once you feed it that you get whatever is programmed in ROM. Obviously I wasn't getting a blinking cursor on the screen, in fact the screen wasn't coming on, period. After a few minutes of sulking over this (can't just replace the terminal with a computer monitor, they're two different beasts entirely), I realized that I hadn't checked the fuse on the monitor. I unscrewed the fuse cap, took out the fuse, and sure enough, it was long-gone. Well, problem solved, maybe. After procuring the correct fuses from my uncle, and replacing the fuse in the monitor. I proceeded to turn on the machine again. This time I heard a loud SNAP! from the monitor. After powering down, I took a look at the fuse I had just replaced. Sure enough, the fuse had blown! After blowing two fuses and consulting my grandfather, I started visually inspecting the monitor, and then gave up. I had no reference for this machine. My mom finally pleaded with me to throw the machine away. So, sadly, I did. After that I found out that the man who built the computer had died a few months earlier. If only I had had the chance to talk to him, I could have figured out what the problem might have been. What sucks now is that with my present knowledge, I could have troubleshooted this machine a little more, and had a working KIM-1 computer, complete with KIM-1 bus based upgrades, and a nicotine smell, sitting in my room with a blinking cursor on the terminal, while trying to figure out what in the heck I had to type in to get the thing to boot from ROM and then tell me that the disk's were old and worn out. So here's a list of things I should have checked for, and things you should check for too if you're in the same situation that I was in. Grab a voltmeter and check the voltages. There should be something like 5 volts or 12 volts for computer based circuitry, different voltages for monitors. I should have checked the power supply feeding the S-100 bus to make sure it was getting power. (BE CAREFUL WITH HIGH VOLTAGE AREAS LIKE THOSE COMMONLY FOUND IN MONITORS) Look at ALL electrolytic capacitors (the metallic cans, usually wrapped in blue, with an ohm rating) and verify their health. A bad electrolytic capacitor may have a bowed out top, depending upon how it died. I don't really know how to accurately verify their health visually (you'll have to do some further research), but I know that this is a must because electrolytic caps don't work when they've dried out. Check all fuses. Duh! Check for bad wiring. This is especially true when dealing with a wire-wrap board, and you'll know what a wire-wrapped board is when you see it. There are more things to look for, but these are the 4 that really would have helped me out a bunch. I believe that the case may have been purhased as a kit from Commodore. If anyone has any info on this at all, please e-mail me.