I just finished reading “Revolution in the Valley – The Insanely Great Story of How The Mac Was Made” by Andy Hertzfeld. I thought I knew many of the stories about the mac’s development, but there are so many more in this book. I never knew how much of the original OS was written in assembly language, I guess I always had assumed it was written in C or Pascal. 128k of memory is so incredibly small, even in those days.