digital equipment corporation · maynard, massachusetts

John Beattie Seat Foam System Changes

About a year after I started in Quality Assurance (about four years after doing the foam seat system), I was invited to a meeting with Production Engineering to discuss making some changes in the foam seat computer control system. Customers were specifying more complex seat designs and more variation in foam density. The Production Engineer wanted to get 10 foam head positions (as opposed to the 5 we had in the system) and to get variable control of freon levels in the foam, making it softer or firmer. They had gotten quotes on the proposed changes and had chosen a vendor to do the modifications. It was going to cost $90,000 and take FOUR months to complete. They asked me what I thought.

I wasn't familiar with the vendor, but from their quotation it looked like they had a lot of experience working with PDP-8 computers, including design and installation of computer control for a new sports scoreboard at Pittsburgh's Three Rivers Stadium. The same person who wrote the stadium software was going to do the foam seat software work. I told them the vendor sounded competent, but I was concerned about the quoted use of digital to analog converters, and I felt the cost was too high.

Production Engineering dismissed my concerns and went ahead with the project. At the project kickoff meeting I was asked to go over the foam seat software with their engineer. I got the program paper tapes, flow diagrams, memory/disk charts, and commented assembly language listings for the system to give them and go over with them. At the meeting I gave an overview of the system to their software engineer. I told her that the system was pretty complex and I would be happy to work with her as needed to understand how it worked. She informed me, in no uncertain terms, that she was an experienced software engineer, having completed the stadium scoreboard program at Three Rivers and she would need no consulting help from me! (Thank-you very much!)

That was fine with me, I had my own job to do anyway. Time went by and I heard nothing about the system changes. Finally after about SIX months I heard that she was ready to test her software. Production was running full steam 7 days a week at the time but they agreed to give her a couple Sundays to try her software. It didn't work at all! She said she needed more production trial time and she didn't want to work on weekends! Production said they could only let her try her software on 3rd shift Sundays (11 Saturday night to 7 Sunday). She refused, so there was a stalemate.

Then her company quit work without completing the job, but still wanted to be paid the full $90K! They presented some paper tapes of her program and a stack of software printouts about four feet high to document her work. The Production Engineer asked me to look at her work. She had no flowcharts and almost no comments in her assembly language listings to show how it was supposed to work. I couldn't make heads or tails of it. But the vendor threatened to sue for payment and upper management caved and paid them!!!

The poor Production Engineer was stuck! He still needed the system modifications before the new model year. He asked me if there was anything I could do to help. I told him that with a couple days overtime work, I could look at the system and possibly make a proposal. I was given a Saturday and Sunday overtime and I put together a proposal that would take me 10 weeks working Saturdays and Sundays to complete. I would not use the digital to analog converters, but would provide 10 computer-selectable freon levels to replace two in the current system. Each individual level could be set by potentiometers on the control panel.

The Production Engineer didn't have much choice but to accept my proposal and try to get it approved by management. At that time paid salary employee overtime was hard to get and management wouldn't approve the work. I was surprised when my boss asked me if I couldn't do the changes in conjunction with my regular job and NO paid overtime. Now I knew I had everyone over the barrel, so I told him absolutely not, my job was requiring a lot of work on the quality/reliability system for the new products and doing the PDP-8 software required a whole different mental state than my regular work.

Well, they finally approved the overtime. I went to work on the system on weekends. Even after five years the PDP-8 assembly language programming came back to me quickly and I used the backup computer system in the plant to enter and assemble the software. The Production Engineer took care of removing the digital to analog converters and making the needed addition of 5 positions and 8 freon levels in the control panels.

My 10th weekend was reserved for testing and debugging the system. By this time production schedules had dropped a bit, and time was critical for getting the new system in operation so I was given daytime Saturday and Sunday with the Production Engineer, electrician, and a few production operators on hand for the trials. We loaded the software and after about a day and a half debugging, it worked nicely (there were still some small issues I worked out with the Production Engineer over the next few weeks). The Production Engineer was relieved and we were able to make the complex pads with the density variations the customer specified, right on the line with the other seat pads.

I received no recognition for this project (really didn't want any). It was fun, the Production Engineer really appreciated it, and I made maybe $10K in overtime pay. Counting the control panel changes the whole project cost a total of maybe $16K, certainly less than $20K. Not only that, the changes provided high quality production of the new seat designs, so it kinda fit my job after all! The changes also made the computer control system flexible enough to make all the seat designs through 1985 when the lines were shut down to make way for airbag production.

But, of course, an outside supplier surely could do this work better than we could! LOL!!

First part of story

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Feel free to contact me, David Gesswein djg@pdp8online.com with any questions, comments on the web site, or if you have related equipment, documentation, software etc. you are willing to part with.  I am interested in anything PDP-8 related, computers, peripherals used with them, DEC or third party, or documentation. 

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