Thanks for another interesting reverse-engineering case.
This made me remember the first project where I have worked after graduating. It was in a metalworking plant, at a huge rolling mill for aluminum sheet.
The controller for that system could be implemented today in a small micro-controller unit or in an FPGA, but in that old installation the controller occupied 3 cabinets. Two cabinets contained an analog computer made with operational amplifiers, which controlled the speed and torque of all the very large DC motors used in the rolling mills.
The third cabinet contained a one-bit programmable logic controller (PLC), which was very similar to Motorola 14500B.
It was even older, so it was made with TTL gates. However, in the next generation of that PLC, the large PCB with many TTL integrated circuits that implemented it was replaced by a simpler board with 14500B and other CMOS ICs.
So I had to write a program for that 14500B-like programmable logic controller. It read data from a large number of sensors and then switched on or off almost a hundred of hydraulic valves that caused the movements of various things and also the electrical power supplies for various devices, e.g. pumps or fans.
Writing programs for it was far less convenient than it would be to do the same thing today with an ARM MCU, but nonetheless it did the required job without problems.
This made me remember the first project where I have worked after graduating. It was in a metalworking plant, at a huge rolling mill for aluminum sheet.
The controller for that system could be implemented today in a small micro-controller unit or in an FPGA, but in that old installation the controller occupied 3 cabinets. Two cabinets contained an analog computer made with operational amplifiers, which controlled the speed and torque of all the very large DC motors used in the rolling mills.
The third cabinet contained a one-bit programmable logic controller (PLC), which was very similar to Motorola 14500B.
It was even older, so it was made with TTL gates. However, in the next generation of that PLC, the large PCB with many TTL integrated circuits that implemented it was replaced by a simpler board with 14500B and other CMOS ICs.
So I had to write a program for that 14500B-like programmable logic controller. It read data from a large number of sensors and then switched on or off almost a hundred of hydraulic valves that caused the movements of various things and also the electrical power supplies for various devices, e.g. pumps or fans.
Writing programs for it was far less convenient than it would be to do the same thing today with an ARM MCU, but nonetheless it did the required job without problems.