Book contents
- Frontmatter
- Contents
- Preface
- Acknowledgments
- Part I Introduction
- 1 The digital abstraction
- 2 The practice of digital system design
- Part II Combinational logic
- Part III Arithmetic circuits
- Part IV Synchronous sequential logic
- Part V Practical design
- Part VI System design
- Part VII Asynchronous logic
- Part VIII Appendix: VHDL coding style and syntax guide
- References
- Index of VHDL design entities
- Subject index
1 - The digital abstraction
from Part I - Introduction
Published online by Cambridge University Press: 01 February 2019
Book contents
- Frontmatter
- Contents
- Preface
- Acknowledgments
- Part I Introduction
- 1 The digital abstraction
- 2 The practice of digital system design
- Part II Combinational logic
- Part III Arithmetic circuits
- Part IV Synchronous sequential logic
- Part V Practical design
- Part VI System design
- Part VII Asynchronous logic
- Part VIII Appendix: VHDL coding style and syntax guide
- References
- Index of VHDL design entities
- Subject index
Summary
Digital systems are pervasive in modern society. Some uses of digital technology are obvious – such as a personal computer or a network switch. However, there are also many other applications of digital technology. When you speak on the phone, in almost all cases your voice is being digitized and transmitted via digital communications equipment. When you listen to an audio file, the music, recorded in digital form, is processed by digital logic to correct errors and improve the audio quality. When you watch TV, the image is transmitted in a digital format and processed by digital electronics. If you have a DVR (digital video recorder) you are recording video in digital form. DVDs are compressed digital video recordings. When you play a DVD or stream a movie, you are digitally decompressing and processing the video. Most communication radios, such as cell phones and wireless networks, use digital signal processing to implement their modems. The list goes on.
Most modern electronics uses analog circuitry only at the edge – to interface to a physical sensor or actuator. As quickly as possible, signals from a sensor (e.g., a microphone) are converted into digital form. All real processing, storage, and transmission of information is done digitally. The signals are converted back to analog form only at the output – to drive an actuator (e.g., a speaker) or control other analog systems.
Not so long ago, the world was not as digital. In the 1960s digital logic was found only in expensive computer systems and a few other niche applications. All TVs, radios, music recordings, and telephones were analog.
The shift to digital was enabled by the scaling of integrated circuits. As integrated circuits became more complex, more sophisticated signal processing became possible. Complex techniques such as modulation, error correction, and compression were not feasible in analog technology. Only digital logic, with its ability to perform computations without accumulating noise and its ability to represent signals with arbitrary precision, could implement these signal processing algorithms.
In this book we will look at how the digital systems that form such a large part of our lives function and how they are designed.
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- Digital Design Using VHDLA Systems Approach, pp. 3 - 21Publisher: Cambridge University PressPrint publication year: 2015
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