Quantum Computing and Other Future Directions in Computer Architectures

This chapter anticipates the road ahead for computer architecture design. We will review the significant technological advances and ongoing trends that have led to the current state of computer architectures. We will then extrapolate current trends and identify some directions that computing system designs are likely to take in the future. We will also examine some potentially disruptive technologies that may substantially alter the evolution of future computer architectures.

This chapter provides some suggested approaches for the professional development of a computer architect. By following these recommendations, you should be able to maintain a skill set that remains relevant and tolerant of future advances, whatever they turn out to be.

After completing this chapter, you will understand the historical evolution of computer architecture that led to its current state and will be familiar with ongoing...

Technical requirements

The files for this chapter, including answers to the exercises, are available at https://github.com/PacktPublishing/Modern-Computer-Architecture-and-Organization-Second-Edition.

The ongoing evolution of computer architectures

Chapter 1, Introducing Computer Architecture, presented a brief history of automated computing devices from the mechanical design of Babbage’s Analytical Engine to the advent of the x86 architecture that continues to serve as the basis for most modern personal computers. This progress relied on several groundbreaking technological achievements, most notably the invention of the transistor and the development of integrated circuit manufacturing processes.

Through the decades since the introduction of the Intel 4004 in 1971, processors have grown dramatically in terms of the sheer number of transistors and other circuit components integrated on a single-circuit die. In concert with the growth in the number of circuit elements per chip, the clock speed of modern devices has increased by several orders of magnitude.

The increase in processor capability and instruction execution speed has unleashed the growth of software development...

Extrapolating from current trends

The capabilities of current-generation processor technology are beginning to push against some significant physical limits that we can expect to constrain the rate of performance growth going forward. These limits certainly will not lead to an abrupt end of improvements in circuit density and clock speed; rather, capability improvements for future processor generations may take place in directions that differ from traditional semiconductor capability growth patterns. To look more closely at future processor performance growth expectations, we begin by returning to Moore’s law and examining its applicability to the future of semiconductor technology.

Moore’s law revisited

The revised version of Moore’s law, published by Gordon Moore in 1975, predicted the number of integrated circuit components per device would double roughly every two years. This law has demonstrated remarkable predictive accuracy for several decades,...

Potentially disruptive technologies

So far, this chapter has focused on trends currently in progress and the potential effects of their extension into the future. As with the introduction of the transistor, we saw that it is always possible that some new technology will appear that creates a drastic break from past experience and leads the future of computing technology in a new direction.

In this section, we attempt to identify some potential sources of such technological advances in the coming years.

Quantum physics

Charles Babbage’s Analytical Engine tried to take the capabilities of purely mechanical computing devices to an extreme that had not been achieved previously. His attempt, while ambitious, was ultimately unsuccessful. The development of practical automated computing devices had to wait until the introduction of vacuum tube technology provided a suitable basis for the implementation of complex digital logic.

Later, the invention of the transistor...

Building a future-tolerant skill set

Given the technological transitions that kicked off the era of transistor-based digital computing, and the possibility of similar future events, it is important for professionals in the field of computer architecture to keep up with ongoing advances and to develop some intuition regarding the likely directions the technology will take in the future. This section provides some recommended practices for keeping up with the state of the art in computing technology.

Continuous learning

Computer architecture professionals must embrace the idea that technology continues to evolve rapidly, and they must devote substantial ongoing effort to monitoring advances and factoring new developments into their day-to-day work and career-planning decisions.

The prudent professional relies on a wide variety of information sources to track technological developments and assess their impact on career goals. Some sources of information, such as traditional...

Summary

Let’s briefly review the topics we’ve discussed and learned about in the chapters of this book:

• In Chapter 1, Introducing Computer Architecture, we began with the earliest design of an automated computing machine, Babbage’s Analytical Engine, and traced the course of digital computer history from the earliest vacuum tube-based computers to the first generations of processors. We also learned about the architecture of an early, but still prevalent, microprocessor: the 6502.
• In Chapter 2, Digital Logic, we learned the basics of transistor technology, digital logic, registers, and sequential logic. We also discussed the use of hardware description languages in the development of complex digital devices.
• Chapter 3, Processor Elements, covered the fundamental components of processors, including the control unit, the ALU, and the register set. The chapter introduced concepts related to the processor instruction set, including details on...

Exercises

1. Install the Qiskit quantum processor software development framework by following the instructions at https://qiskit.org/documentation/getting_started.html. The instructions suggest the installation of the Anaconda (https://www.anaconda.com/) data science and machine learning toolset. After installing Anaconda, create a Conda virtual environment named qisketenv to contain your work on quantum code and install Qisket in this environment with the command pip install qiskit. Make sure that you install the optional visualization dependencies with the pip install qiskit-terra[visualization] command.
2. Create a free IBM Quantum account at https://quantum-computing.ibm.com/. Locate your IBM Quantum Services API token at https://quantum-computing.ibm.com/account and install it into your local environment using the instructions at https://qiskit.org/documentation/stable/0.24/install.html.
3. Work through the example quantum program at https://qiskit.org/documentation...