ATR 8000

[wayne5]

I also found a D size drawing of the Xerox 820 board. Interesting, the mail out said that this board was sold to Big Board users. I don't remember them, but I'm not surprised, in that the Xerox 820 was the Big Board. The D size drawings are so fragile that I'm not sure how to deal with them. They are mostly Blue Line copies, and eventually they will fade completely out.

 

I found my WD book and I got the numbers wrong on the story about the 1771. I worked for Percom and had a lot to do with the 'Doubler' product for the TRS-80. The project existed before I came, but it was not usable. There was a software incompatibility problem. The 179? Series DD controller couldn't read/write/don't remember exactly, the 1771 single density files. They had already found an unused register in the controller memory map to use as a switch bit for single/double density. And the digital data separator was inadequate, but they didn't know about this problem until I got there.

 

My contribution to the Doubler was the idea to put a socket on the daughter board and just use the 1771 for single density. And after the data separator problem popped up, solving that problem. I have to give credit to a guy named Richard Benjamin, who spent days with me trying to solve the separator problem. One day he just quit working on it and told me I knew as much as he did about the problem and that he was sure I would crack it eventually. It could have been some money thing with Harold Mauch, the owner of Percom, I never found out. I kept banging on it until, with a little help from Harold, the problem was solved. The TRS-80 Expansion Interface had very little headroom in the power supply, and analogue data separators of the day were higher current than we thought it could handle. To make life more interesting. The data pattern for a formatted disk was E5E5, so when you formatted a disk the system would read each sector again to see if the sector was good. This pattern turned out to be inadequate for formatting DD and the disks would pass when real data was recorded, the last 5 tracks had errors. All this wasn't discovered until units had been shipped and Richard and I were on the hot seat, trying to find answers. First we found that 6DB6 was the 'worst case' and format kicked out every disk after that. The final solution was a small state machine that digitally had analogue properties using a TTL 32 byte prom with a transistor turning the gas gusseling part on just long enough to read the byte and back off so we could stay in line with the power supple problem. Harold supplied the transistor circuit.  It was a big success because a single sided single density drive from Radio Shack was $500 and this $200 card doubled your space.

 

I also worked for a company named Aerocomp, John Lanseoni. He had a Radio Shack franchise in Lizard Flats, Arizona where he bought computers, and after they were delivered from Ft Worth, had them loaded on a truck and taken back to Ft Worth to Aerocomp. He had a double density project as well. His was farther along, but the engineer on the project didn't know about the power supply problem. We came up with a 4046 PPL version that used an FET for the pump up, pump down section that took even less power than the Doubler and being analogue, was better at separating data. Aerocomp advertised that they were better, but the extra headroom didn't really matter, the Doubler was good enough.

 

I didn't intend to write War and Peace, and there is a lot left out. I'm glad that people are collecting these units. If I can help just send me a note.

wayne smith   

[wayne5]

2 minutes ago, MrFish said:

 

Thanks for the scans.

 

Just quickly, I rotated the pages, ordered the schematics, and put the BOM and schematics into separate PDF's.

 

SWP ATR8000 - Specs & Pricing.pdf 337.26 kB · 0 downloads

SWP ATR8000 - Schematics.pdf 841.43 kB · 0 downloads

SWP ATR8000 - BOM.pdf 346.52 kB · 0 downloads

 

Cool! If I find any other documentation, I will post it.

[+MrFish]

36 minutes ago, wayne5 said:

Cool! If I find any other documentation, I will post it.

Sounds great. Thanks again.

 

[_The Doctor__]

People enjoy the stories, the more information the better. Even if you remember something incorrectly after 40 years... no one could fault you, if you realize anything was miss remembered just point it out or correct it and be at ease. You are speaking to people whom many have read libraries full of white papers and System reference books, real life information no matter how dull such thoughts might be to you is very interesting to many others. It gives an idea of how things came to be for a good number of people whom weren't there in the wild west era of computer development and products.

Edited March 7, 2023 by _The Doctor__

[phaeron]

3 hours ago, wayne5 said:

I found my WD book and I got the numbers wrong on the story about the 1771. I worked for Percom and had a lot to do with the 'Doubler' product for the TRS-80. The project existed before I came, but it was not usable. There was a software incompatibility problem. The 179? Series DD controller couldn't read/write/don't remember exactly, the 1771 single density files. They had already found an unused register in the controller memory map to use as a switch bit for single/double density. And the digital data separator was inadequate, but they didn't know about this problem until I got there.

If you have stories or artifacts from Percom, we'd love to read about that too -- several of us have been piecing together the chronology of the various Percom drive revisions in various threads including this one:

 

https://forums.atariage.com/topic/320283-percom-rom/page/2/

 

[+SoulBuster]

just ran accross this article about the ATR-8000 in Analog #44

 

Interview Russel and Wayne Smith ATR-8000.pdf