Always on. Always connected. Computers nowadays are everywhere. They are changing our way of life.
Today we can access our bank account on our phone but do you know how risky it is to do your personal banking in a coffee shop or at an airport? An increasing number of devices — not only mobile phones but also cars, security cameras, home appliances are connected to the Internet. Therefore, we cannot ignore the dangers of the world’s ever growing reliance on computer networks: online privacy, loss of control over personal data and the omnipresent threat of cybercrime and cyber terrorism.
“Understanding the Digital World” takes us inside this new world. This book is not meant for engineers, physicists or mathematicians, it is addressed to the general public. It tackles questions we all ask ourselves but never had the answers. Who knows whether iPhones and Android phones are totally different or similar? And are we sure our emails are really safe?
Brian Kernighan has a friendly approach and the knack to express himself in an extraordinarily clear fashion. This book familiarizes us with the basic ideas of digital systems, which will not change “so if you understand those, you’ll understand tomorrow’s systems too, and you’ll be in a better position to deal with the challenges and the opportunities that they present” wrote Kernighan.
Today’s computers are very similar to those made in the 1950s in the sense that “how it does what it does” is still the same. What has changed is the way a computer is built and how fast it runs. Personal computers are now much smaller, cheaper, faster and more reliable. Is there a difference between a Mac and a PC? PCs are cheaper than Macs but according to Kernighan, people choose Macs because they equate them with reliability, quality, aesthetics, and an excellent customer service for which consumers are willing to pay more.
The same issue concerns mobile phones. IPhones are more expensive than Android phones but does that make them better? Some customers prefer the iPhone because it is functional and aesthetic. The truth is that the hardware responsible for the computing in an iPhone and in an Android is very similar. In fact the functional properties of today’s digital computers and our phones are the same, “they all can compute exactly the same things,” wrote Kernighan.
Every computer, whatever the brand, consists of a processor (the CPU), some primary memory (RAM), some secondary storage (a disk) and other components connected by wires known as a bus.
The CPU is the brain. It does arithmetic operations, moves data around, and controls the operation of other components. The primary memory or random access memory (RAM) stores not only the data that the CPU is working on but also the instructions that tell the CPU what to do with the data. If you want your computer to run faster, the best thing you can do is buy extra RAM.
One can say that a computer is a general-purpose machine. It takes its instructions from memory but one can modify the computation it performs by introducing different instructions in the memory.
One fundamental notion is related to how computers represent information, or in other words, how computers are digital processors. First, it is necessary to know the difference between analog and digital. An analog watch has an hour hand, a minute hand and a second hand whereas a digital watch and a mobile phone show time with digits. An analog thermometer comes with a column of red liquid, which reacts to small changes of temperature whereas a digital thermometer flashes a number. It shows 37 for all temperatures between 36.5 and 37.5.
Although we are in a world, which is analog, the modern technology we use is digital. Instead of storing words, pictures and sounds in the form of plastic films or magnetic tapes, we first convert the information into numbers (digits) and display or store the numbers instead.
“Digital data is easy for computers to work with. It can be stored, transported and processed in many ways. Digital information can be compressed by squeezing out redundant or unimportant information. It can be encrypted for security and privacy…it can be shipped anywhere via the Internet…” wrote Kernighan. This cannot be achieved with analog information but on the other hand, analog systems, like clay tablets, papyrus, paper and photographic films, have withstood the test of time. The future will tell whether digital systems will last.
In a digital camera, the lens projects the image onto a rectangular surface covered with tiny light-sensitive detectors that are placed behind red, green and blue filters. Each detector stores an amount of electric charge proportional to the amount of light received. These charges are converted into numeric values. Therefore a digital image shows a pattern of numbers that represent the different intensities of light.
Mobile phones have completely revolutionized our way of life. This wireless communication technology barely known in the 1980s is now used by more than half of the world’s population. Smartphones are now used for Internet access so we can send mails, browse, shop and do some social networking. Smartphones are now replacing watches, cameras and they provide games, music and films.
Digital technology has provided numerous benefits but it has had a negative impact on our personal privacy and security “and this is getting worse” believes Kernighan. The Internet has had a significant impact on our security because our lives have become an easy prey for electronic intruders. The truth is that practically everything you do with a computer, a phone or a credit card generates data about you that is systematically collected, analyzed, saved forever and often sold to organizations that you have never heard of.
We should think seriously when we go online. Before sending a mail or posting or tweeting, pause a moment and ask whether you would be comfortable if your words or pictures appeared on the front page of the New York Times or as the lead story on a TV news program. Your mail, texts and tweets are likely to be stored forever and could potentially reappear in some embarrassing context years later.
Cryptography, the art of “secret writing,” is our best defense to preserve personal information. Incidentally, Apple encrypts all the contents of iPhones running iOS 9, using a key provided by the user. In 2016, the FBI attempted to force Apple to break the encryption on an iPhone that had been used by the terrorists who killed 14 people in San Bernardino, California, before being killed. The FBI requested access to the content of one of the phones. Apple claimed that if it created a special mechanism to access the information it would set a precedent that would seriously weaken all phone security.
“My personal position is that strong encryption is one of the few defenses that ordinary people have against government over-reaching and criminal invasion, and we must not give it up,” writes Kernighan.
The author shares his enthusiasm for an amazing technology. One can only be excited by the huge promise of the Internet and technology to deliver better education, health care, transport and commercial opportunities. Technological change is an ongoing process.
“It’s going to be fun to see how things evolve over the next few years. I hope that this book will help you anticipate, cope with, and positively influence some of the inevitable changes,” concludes Kernighan. In a very near future, we can expect to see sophisticated devices becoming incorporated into our bodies. Bionics is no longer science fiction! We could one day all have chips in our brains.
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