Umm why you went through the lengths you did to take snippets of my response out of context and to pick apart one of my first my posts here is beyond me. You don't think I was serious about COBAL at all do you... did you miss the stapler part? PIC chips are everywhere still... especially in the cheaper $80.00 AC units and lots of cheap companies still use OTP ROM or Eprom which still can be found in modern MCU's today, (I'm looking at examples right now). Rooftop units and quality units use better parts and have more complexity and will most certainly use a dedicated MCU, EEproms or flash, etc.. I too have experience in commercial HVAC, have run a repair shop for over 14 years, and a degree in Industrial Electronics and Robotics, so I like to think I know what I'm doing. The way you dissected and promptly decided to debunk everything I posted has made me feel quite unwelcome especially coming from an Moderator. Quote.