Book Image

Modern Computer Architecture and Organization – Second Edition - Second Edition

By : Jim Ledin
Book Image

Modern Computer Architecture and Organization – Second Edition - Second Edition

By: Jim Ledin

Overview of this book

Are you a software developer, systems designer, or computer architecture student looking for a methodical introduction to digital device architectures, but are overwhelmed by the complexity of modern systems? This step-by-step guide will teach you how modern computer systems work with the help of practical examples and exercises. You’ll gain insights into the internal behavior of processors down to the circuit level and will understand how the hardware executes code developed in high-level languages. This book will teach you the fundamentals of computer systems including transistors, logic gates, sequential logic, and instruction pipelines. You will learn details of modern processor architectures and instruction sets including x86, x64, ARM, and RISC-V. You will see how to implement a RISC-V processor in a low-cost FPGA board and write a quantum computing program and run it on an actual quantum computer. This edition has been updated to cover the architecture and design principles underlying the important domains of cybersecurity, blockchain and bitcoin mining, and self-driving vehicles. By the end of this book, you will have a thorough understanding of modern processors and computer architecture and the future directions these technologies are likely to take.
Table of Contents (21 chapters)
18
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19
Index

Latches

Combinational logic does not directly permit the storage of data as is needed for digital functions such as processor registers. Logic gates can be used to create data storage elements by using feedback from a gate output to the input of a gate preceding that point in the signal chain.

A latch is a single-bit memory device constructed from logic gates. Figure 2.10 shows a simple type of latch called the Set-Reset, or SR, latch. The feature that provides memory in this circuit is the feedback from the output of the AND gate to the input of the OR gate:

Figure 2.10: SR latch circuit

Figure 2.10: SR latch circuit

Based on the inputs S and R, the circuit can either set the output Q to high, reset Q to low, or cause the output Q to be held at its last value. In the hold state, both S and R are low, and the state of the output Q is retained. Pulsing S high (going from low to high then back to low) causes the output Q to go high and remain at that level. Pulsing R high causes Q to go low and...