For years, I'd been trying to find someone who actually knows how the coding works, has compiler info, etc. to write and modify the E series code, but no one here still alive seems to have any real info on it. I have accumulated dozens of P1 chips with code, and really can't make heads or tails out of it. The PROM code is compiled and applicable to the microprocessor, so having a cal-doc would be the holy grail to these. But back in the 80s, all that stuff was closely guarded and kept locked away for fear of retaliation from the gaming commission, I think.
Still waiting for someone on this forum to interject....