Modern Computer Architecture and Organization

Learn x86, ARM, and RISC-V architectures and the design of smartphones, PCs, and cloud servers

Jim Ledin

• Publisher: Packt Publishing
• Year: 2020
• ISBN:
  9781838987107
• Topic: Computer Science
• Subtopic: Hardware
• Index: Computer Science

A no-nonsense, practical guide to current and future processor and computer architectures, enabling you to design computer systems and develop better software applications across a variety of domains

Key Features

• Understand digital circuitry with the help of transistors, logic gates, and sequential logic
• Examine the architecture and instruction sets of x86, x64, ARM, and RISC-V processors
• Explore the architecture of modern devices such as the iPhone X and high-performance gaming PCs

Book Description

Are you a software developer, systems designer, or computer architecture student looking for a methodical introduction to digital device architectures but overwhelmed by their complexity? This book will help you to learn how modern computer systems work, from the lowest level of transistor switching to the macro view of collaborating multiprocessor servers. You'll gain unique insights into the internal behavior of processors that execute the code developed in high-level languages and enable you to design more efficient and scalable software systems.The book will teach you the fundamentals of computer systems including transistors, logic gates, sequential logic, and instruction operations. 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 how to write a quantum computing program and run it on an actual quantum computer. By the end of this book, you will have a thorough understanding of modern processor and computer architectures and the future directions these architectures are likely to take.

What you will learn

• Get to grips with transistor technology and digital circuit principles
• Discover the functional elements of computer processors
• Understand pipelining and superscalar execution
• Work with floating-point data formats
• Understand the purpose and operation of the supervisor mode
• Implement a complete RISC-V processor in a low-cost FPGA
• Explore the techniques used in virtual machine implementation
• Write a quantum computing program and run it on a quantum computer

Who this book is for

This book is for software developers, computer engineering students, system designers, reverse engineers, and anyone looking to understand the architecture and design principles underlying modern computer systems from tiny embedded devices to warehouse-size cloud server farms. A general understanding of computer processors is helpful but not required.

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Section 1: Fundamentals of Computer Architecture

In this section, we will begin at the transistor level and work our way up to the computer system level. You will develop an understanding of the key components of modern computer architectures.

This section comprises the following chapters:

• Chapter 1, Introducing Computer Architecture
• Chapter 2, Digital Logic
• Chapter 3, Processor Elements
• Chapter 4, Computer System Components
• Chapter 5, Hardware–Software Interface
• Chapter 6, Specialized Computing Domains

Chapter 1: Introducing Computer Architecture

The architecture of automated computing devices has evolved from mechanical systems constructed nearly two centuries ago to the broad array of modern electronic computing technologies we use directly and indirectly every day. Along the way, there have been stretches of incremental technological improvement interspersed with disruptive advances that have drastically altered the trajectory of the industry. These trends can be expected to continue into the future.

In past decades, the 1980s, for example, students and technical professionals eager to learn about computing devices had a limited range of subject matter available for this purpose. If they had a computer of their own, it might have been an IBM PC or an Apple II. If they worked for an organization with a computing facility, they might have used an IBM mainframe or a Digital Equipment Corporation VAX minicomputer. These examples, and a limited number of similar systems, encompassed most people's exposure to computer systems of the time.

Today, numerous specialized computing architectures exist to address widely varying user needs. We carry miniature computers in our pockets and purses that can place phone calls, record video, and function as full participants on the Internet. Personal computers remain popular in a format outwardly similar to the PCs of past decades. Today's PCs, however, are orders of magnitude more capable than the first generations of PCs in terms of computing power, memory size, disk space, graphics performance, and communication capability.

Companies offering web services to hundreds of millions of users construct vast warehouses filled with thousands of closely coordinated computer systems capable of responding to a constant stream of requests with extraordinary speed and precision. Machine learning systems are trained through the analysis of enormous quantities of data to perform complex activities, such as driving automobiles.

This chapter begins by presenting a few key historical computing devices and the leaps in technology associated with them. This chapter will examine modern-day trends related to technological advances and introduce the basic concepts of computer architecture, including a close look at the 6502 microprocessor. These topics will be covered:

• The evolution of automated computing devices
• Moore's law
• Computer architecture

The evolution of automated computing devices

This section reviews some classic machines from the history of automated computing devices and focuses on the major advances each embodied. Babbage's Analytical Engine is included here because of the many leaps of genius contained in its design. The other systems are discussed because they embodied significant technological advances and performed substantial real-world work over their lifetimes.

Charles Babbage's Analytical Engine

Although a working model of the Analytical Engine was never constructed, the detailed notes Charles Babbage developed from 1834 until his death in 1871 described a computing architecture that appeared to be both workable and complete. The Analytical Engine was intended to serve as a general-purpose programmable computing device. The design was entirely mechanical and was to be constructed largely of brass. It was designed to be driven by a shaft powered by a steam engine.

Borrowing from the punched cards of the Jacquard loom, the rotating studded barrels used in music boxes, and the technology of his earlier Difference Engine (also never completed in his lifetime, and more of a specialized calculating device than a computer), the Analytical Engine design was, otherwise, Babbage's original creation.

Unlike most modern computers, the Analytical Engine represented numbers in signed decimal form. The decision to use base-10 numbers rather than the base-2 logic of most modern computers was the result of a fundamental difference between mechanical technology and digital electronics. It is straightforward to construct mechanical wheels with ten positions, so Babbage chose the human-compatible base-10 format because it was not significantly more technically challenging than using some other number base. Simple digital circuits, on the other hand, are not capable of maintaining ten different states with the ease of a mechanical wheel.

All numbers in the Analytical Engine consisted of 40 decimal digits. The large number of digits was likely selected to reduce problems with numerical overflow. The Analytical Engine did not support floating-point mathematics.

Each number was stored on a vertical axis containing 40 wheels, with each wheel capable of resting in ten positions corresponding to the digits 0-9. A 41st number wheel contained the sign: any even number on this wheel represented a positive sign and any odd number represented a negative sign. The Analytical Engine axis was somewhat analogous to the register used in modern processors except the readout of an axis was destructive. If it was necessary to retain an axis's value after it had been read, another axis had to store a copy of the value. Numbers were transferred from one axis to another, or used in computations, by engaging a gear with each digit wheel and rotating the wheel to read out the numerical value. The axes serving as system memory were referred to collectively as the store.

The addition of two numbers used a process somewhat similar to the method of addition taught to schoolchildren. Assume a number stored on one axis, let's call it the addend, was to be added to a number on another axis, let's call it the accumulator. The machine would connect each addend digit wheel to the corresponding accumulator digit wheel through a train of gears. It would then simultaneously rotate each addend digit downward to zero while driving the accumulator digit an equivalent rotation in the increasing direction. If an accumulator digit wrapped around from nine to zero, the next most significant accumulator digit would increment by one. This carry operation would propagate across as many digits as needed (think of adding 1 to 999,999). By the end of the process, the addend axis would hold the value zero and the accumulator axis would hold the sum of the two numbers. The propagation of carries from one digit to the next was the most mechanically complex part of the addition process.

Operations in the Analytical Engine were sequenced by music box-like rotating barrels in a construct called the mill, which is analogous to the processing component of a modern CPU. Each Analytical Engine instruction was encoded in a vertical row of locations on the barrel where the presence or absence of a stud at a particular location either engaged a section of the Engine's machinery or left the state of that section unchanged. Based on Babbage's hypothesized execution speed, the addition of two 40-digit numbers, including the propagation of carries, would take about three seconds.

Babbage conceived several important concepts for the Engine that remain relevant today. His design supported a degree of parallel processing that accelerated the computation of series of values for output as numerical tables. Mathematical operations such as addition supported a form of pipelining, in which sequential operations on different data values overlapped in time.

Babbage was well aware of the complexities associated with mechanical devices such as friction, gear backlash, and wear over time. To prevent errors caused by these effects, the Engine incorporated mechanisms called lockings that were applied during data transfers across axes. The lockings forced the number wheels into valid positions and prevented accumulated errors from allowing a wheel to drift to an incorrect value. The use of lockings is analogous to the amplification of potentially weak input signals to produce stronger outputs by the digital logic gates in modern processors.

The Analytical Engine was programmed using punched cards and supported branching operations and nested loops. The most complex program for the Analytical Engine was developed by Ada Lovelace to compute the Bernoulli numbers.

Babbage constructed a trial model of a portion of the Analytical Engine mill, which is currently on display at the Science Museum in London.

ENIAC

ENIAC, the Electronic Numerical Integrator and Computer, was completed in 1945 and was the first programmable general-purpose electronic computer. The system consumed...