Computer architecture is the conceptual design and fundamental operational structure of a computer system. It is a blueprint and functional description of requirements (especially speeds and interconnections) and design implementations for the various parts of a computer — focusing largely on the way by which the central processing unit (CPU) performs internally and accesses addresses in memory.

List of eBooks:
Computer Organization and Architecture by William Stalling 6th Edition

Computer Organization and Design by David A Patterson and John L Hennessy

Computer Architecture - A Quantitative Approach 3rd edition

Digital Design and Computer Architecture