Reply to post: Not only computer gear

Reliable system was so reliable, no one noticed its licence had expired... until it was too late

Voyna i Mor Silver badge

Not only computer gear

People did strange things in the early 1980s. This was a machine control system based around a TMS9900. No source code of course. The "woodpecker" function had failed. This is a function in which a drill is progressively inserted deeper and deeper withdrawing each time so it gets swarf cleared and lubricated. Yes there are the expected jokes about it.

I used to be able to write TMS9900 assembler in my head so took a dump of the eprom and had a look. No sign of a cycle with varied timing.

To cut a long story short, the designers of the thing obviously hadn't understood the use of interrupts and the timers and had built an analogue circuit using a unijunction transistor, which had failed. It was more or less unobtainable but the circuit was easily redesigned using a PUT.

At the same company, three years in a row the MRP supplier failed to deliver a new licence till two days after the old one expired, despite having been paid, and then were shocked when we migrated to a more modern system run by people who could get their act together. They were mainly shocked because we were able to extract their database instead of paying them £1500 a day to do it.

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