1980s computer controls Grand Rapids Public School heat and AC
I remember a conversation I had with a friend's father, an HVAC engineer. He brought home a control board one-time, showed me the sensor inputs and control outputs. I don't remember how many there were, but let's say a dozen of each.He described how a sensor in would connect to this spot and feed the system temperatures from a sensor in some remote part of the building. The control output would then go to the appropriate HVAC system and turn on/off A/C, heat or whatever to get the temperature to what it needed to be at.The system would spider out around the building with these sensors and regulate the building's temperature.At the heart of the board (which looked like a PC motherboard) was the CPU, a z80, already hilariously ancient when he showed this to me. So I asked him "why not use a more modern CPU?"He responded, "why? This z80 can control an office building's entire HVAC system, and poll each sensor 200 times a second, how many times per second do you need? Temperature in a zone doesn't change that fast."It was my introduction to the concept of "Lateral Thinking with Withered Technology" https://en.wikipedia.org/wiki/Gunpei_Yokoi#Lateral_Thinking_...