I ordered for this book because it contains information I cannot find in other Assembly language books. It deals with the Machine codes, interrupts, memory dumps, ROM BIOS routines, writing RAM resident programs etc. I was interested in these type of things because they help me know more about how to find information on a damaged drive, and in identifying malicious code on a drive. The book is very old, since it deals with 16-bit Assembly, but the information on how it relates to the hardware is very useful.