I usually take meticulous notes when working on things such as this. I will dig out my notes and post my findings on another forum thread, perhaps another day.This was an extraordinary bug and so I'm intrigued! How was the hardware interfaced to the processor, was it memory-mapped? What system call did the library use to write the byte(s)? What data type? If the extra byte didn't get on to the bus, where did it go? Please provide more info as this sounds like a fascinating case study.