I was asked by Ciba Geigy to redesign a piece of pharmaceutical equipment used for growing and purifying antibiotics. Their problem was that everything was lost if there was a power cut. It was basically a sequence controller that ran a complex glass helical assembly. There was a double helix, one spiral running from left to right and the other right to left. It was about 2 metres long by 35 cm diameter. In operation each section was partially filled with culture. Firstly the control shock the culture a bit each way to mix the contents. Then it was left to stand for a while for the contents to separate . It then turned slowly in one direction and part of the culture at the top was able to run through connecting tubes to the other helix, collecting the required part. The operation then repeated itself again. This went on for many hours. The original control system was very basic and crude with no memory of what had happened so far and very little time adjustments. My system was based on TTL control with all operations adjustable and a sequence controller that remembered how far it had got if there was a power cut. It worked superbly for many years. I used to pop in now and again to check all was well.