The Book of the World is digital

Chapter One what's in the computer
PC, many years have passed, the basic structure has not changed.
Logical constructs: CPU, main memory (RAM), Large capacity memory (disk) and other various parts (mouse, keyboard, monitor CD, printer) are connected by bus.
Von Neumann's paper is now worth reading, and this architecture is called the von Neumann architecture.

CPU: Intel duo Core 2.1GHz, two cores two cpu,hz number of times per second can be calculated

RAM: Random access (the CPU can quickly access information from anywhere in the same speed) memory is volatile.

Moore's Law: Gordon Moore, Intel co-founder and long-term CEO, "filling in more parts in integrated circuits": with the development of technology, the number of devices (mainly transistors) that can be manufactured inside an integrated circuit of a given size doubles roughly every year. It was later amended to 2 years, others considered 18 months.

At some stage, Moore's law will fail. Several times before some people have concluded that Moore's law limit has arrived, but later found a way to break the limit. Now it's time again: some circuits contain very few electrons, so small structures are hard to control.

Second Zambit, bytes and information representation

Mode conversion: Analog signals are converted into digital signals. Sounds, images, character ASCII, and Unicode

"There are only 10 kinds of people in the world who understand the binary and do not understand the binary. ”

Chapter III in-depth understanding of CPU
Use a toy computer to explain how the CPU works.

The RAM is slower than the CPU operation. The most recently used instructions and data are stored between the CPU and ram through a small amount of high-speed memory, which is called caching. There are other ways to make the processor run faster, such as pipelining (which allows the CPU to alternately get and execute instructions) and the other is to run multiple CPUs concurrently. Comparing CPU speed does not make much sense, one processor is faster than the other, and does not have to be too serious, specific problems specific analysis.

Typical CPUs typically have two to three caches, which increase in size and decrease in speed. First-level cache, level two cache, and level three cache.
The idea of caching almost everywhere, open Word close, then open, open speed will improve, or even Google search a keyword, a search again, the speed will improve.

All computers are equivalent: Universal Turing machine.

Turing Test: A computer and a person, through the keyboard and the display rain another questioner to communicate. By answering, the questioner determines which is the person and which is the computer.

Abbreviation captcha=completely Automated public Turing test to tell Computers and humans apart in order to differentiate between computer and human's fully automated common Turing test. can be interpreted as a verification code.

Still, there are so many things that we don't know how to use bits, not to mention how to use a computer. For example, the most important things in daily life: art, creativity, truth, Beauty, love, honor, and value.

Fourth Chapter algorithm

Algorithm: A series of steps that ensure that a particular calculation process is performed correctly.
Linear algorithm: The time spent is proportional to the amount of data processed

Binary search: Want to find the designated person in the phone book, the middle of the first to find, every time to half, similar to look up the dictionary. It is also used in the knockout stages of the tournament, half of each round.

Sort by: Quick sort, Tonihol, first on all groupings to sort, piecemeal one way.

Difficulty rain complexity: As the amount of data increases, the workload increases. For fast ordering, it is n Logn, which is less than the linear n difference but acceptable, followed by n^2, followed by exponential growth.

Since the world is digital, that person should also be part of the world, and when a person's many things are quantified, then privacy becomes a very deadly thing. We live in this digital age, with the convenience of being at the same time taking on the risk of privacy, or by giving up some of our privacy data for convenience, such as the map app, where there will be more and more privacy debates, perhaps more ethical.

The Book of the World is digital