Don Tarbell's computer

Hi Sam and all, At 11:34 AM 9/9/98 -0700, you wrote: I called Don about 18 months ago asking if he could give me some information on his earlier homebrew computers. I know he started in the mid 1960's with a RTL (resistor transistor logic) system. He didn't know where to locate any at that time. I also said I'd be interested in other earlier computer literature. I knew a little about his cassette interface from BYTE ads. He and his wife Brenda took my mumber. Well this week she called, She had taken care of most things and was moving this Sat. She had a small box of literature that I could pick up if I wanted it. I said Sure! The box has several of the Micro 8 newsletters, some IMSAI stuff, some 1977 Bytes, source code listings for Processor Tech Basic-5 and Software package No. 1, +... I was happy to have found it. Her last trash pickup would have been the next day. Why I'm writing is thrown out at the street was his (their) last homebrew computer, "PUTER". Brenda said I was welcome to it. She had spent many hours soldering the boards, they had dropped all work on it when the Altair came out. I would like to get it to do at least something. The problem which makes it (maybe too) difficult is that ALL documentation is lost. Many wires are broken. I have 3 units: 1. the rack "mainframe" which include 16 address lights, 8 data switches, 4 "file address" switches + about 10 others. The main power supply is 5V, 15 Amp. The backplane has space for 16 cards. There are 8. 2. A spare? cardcage with 7 misc I/O cards? The edge connectors are wired partially, but it looks like a card storage unit. 3. A "GA" logo core memory card, 15 x17 inches (38x43cm). Not sure if it was connected. Brenda said Don collected all types of computer surplus for his projects. I left behind a hard disk unit in a rack in very poor condition. The single platter had been exposed for over 10 years... Most of the cards are Douglas Electronics 11DE5. (They are in San Leandro in N. Ca. and still sell these. You can see their line at www.douglas.com. they also sell DEC, S-100 and other form cards at attractive prices, in my opinion, if anyone needs them.) The cards 11DE5 hold up to 36 16 pin dips. They are soldered together with vari-colored telephone wire. (AWG 24, about 0.5mm). Am example of what I have is a serial card (from the DB-25S) which contains 20 IC's. 3-7401 2-7402 2-7404 1-7421 1-7427 1-7430 1-7442 2-7474 2-7496 5 bit shift reg. 1-74163 1-74180 parity gen. 2-9602 (T. and R clocks) 1-8273 10 bit shift register. This was in the "spare" cardcage. Have not traced this board circuit or any other yet! May start with a simple one with only 8 IC's. Have not recognized any computer function yet, such as a ALU, address latch, etc. Should I start by finding the data and address busses on the backplanes? Or does this sound like an impossibly long task??? Brenda said this system was used to start development on a cassette system before S-100 came along. It is really amazing that he interfaced a hard disk to it and wrote an operating system for it. She said one output devicer was an X-Y recorder. If anyone has any of the Amateur Computer Society issues that have any descriptions, I would be very interested. -Dave