Historically, the electronic circuits used for communications and processing were analog. Now digital electronic circuits are widely used in communications and computers. What factors drove this revolution from analog to digital?
A few major developments that led to the digital revolution:
Shannon's publications in switching circuits and information theory is the theoretical framework of digital electronics and digital communications. In his Master's work, A symbolic analysis of relay and switching circuits (in 1936), he showed that Boolean logic could be applied to Switching circuits. In his publication in The Bell System Technical Journal in 1948, A Mathematical Theory of Communication, Shannon showed that communications can be done digitally with no loss of information subject to certain conditions which he derived and proved. Shannon also worked on Cryptography, the backbone of cybersecurity.
Complementary metal–oxide–semiconductor (CMOS) logic was developed by Chih-Tang Sah and Frank Wanlass at Fairchild Semiconductor in 1963 (Source: https://www.computerhistory.org/siliconengine/complementary-mos-circuit-configuration-is-invented/). CMOS had lower power consumption.
By the mid-1970s, digital system designers eager to create higher-performance devices were frustrated by having to use off-the-shelf large-scale-integration logic. It stymied their efforts to make chips sufficiently compact or cost-effective to turn their very large-scale visions into timely realities. In 1978, a landmark book titled Introduction to VLSI Systems changed all of that. Co-authored by Mead, the Gordon and Betty E. Moore professor of computer science and electrical engineering at the California Institute of Technology, and Conway, research fellow and manager of the VLSI system design area at the Xerox Palo Alto Research Center, the book provided the structure for a new integrated system design culture that made VLSI design both feasible and practical. Introduction to VLSI Systems resulted from work done by Mead and Conway while they were part of the Silicon Structures Project, a cooperative effort between Xerox and Caltech. Mead was known for his ideas on simplified custom-circuit design, which most semiconductor manufacturers viewed with great skepticism but were finding increasing support from computer and systems firms interested in affordable, high-performance devices tailored to their needs. Conway had established herself at IBM's research headquarters as an innovator in the design of architectures for ultrahigh-performance computers. She invented scalable VLSI design rules for silicon that triggered Mead and Conway's success in simplifying the interface between the design and fabrication of complex chips. The structured VLSI design methodology that they presented, the Mead-Conway concept, helped bring about a fundamental reassessment of how to put ICs together.
Source: In 2002 Mead and Conway were inducted in the Electronics Design Hall of Fame in recognition of their pioneering work in VLSI chip design methods. This is what the entry said about their work.
Intel introduced the first commercial microprocessor, the 4-bit Intel 4004, in 1971. This was followed by other microprocessors.
Computer-aided VLSI design, coupled with the ingenuity and creativity of modern digital designers and computer/communication system architects is the reason behind all the modern digital marvels of today.
Factors that drove the digital revolution, and continue to drive it today:
- Error-correcting capability using digital logic.
- Low cost of manufacturing digital devices.
- Digital electronics has noise immunity. See: Why is an analog circuit more susceptible to noise than a digital one?
- Ease of digital design and verification using Hardware Description and Verification Languages and High-Level Synthesis tools.
- Information compression algorithms are used on digital data to enable efficient storage and digital communication.
- Cryptographic techniques for information security are used in digital communication to provide confidentiality, integrity and authentication.
- Programmability: Digital devices such as processors and microcontrollers are programmable, which allows them to perform different functions by writing software.
The major advantage of digital is that it is generally deterministic and precise. This is not necessarily true of analog, especially in manufacturing. A digital circuit usually either works perfectly or not at all. For analog, there is a whole range of performance between pass and fail.
If you're thinking in practical real world example terms impact of digital technology on daily life I would say the rollout of digital telephony which occurred around the same time as the development of the first microprocessors in the early 70's