Microcomputer architecture and programming Book

I read this book probably shortly after it came out. At the time, I was writing a simulation in Pascal and needed to optimize some sections in assembly language. I ended up reading this book cover to cover and using lessons from it in many programming tasks. I found it fascinating and helpful. Not exactly a cookbook, but more a way to think about programming.

I don't program in assembly anymore, but I have fond memories of reading this book.