"The World Is Digital" (1/4)

After a week of reading the first part of the book-the hardware, this book is really vivid compared to those computer professional books (rectification C programming), the author is good at taking his own example, the language is humorous. Read this book a lot of harvest, took me into the computer door, the following is the key excerpt.

First, what is in the computer

1, a computer has the following structure: a processor (CPU), some main memory (memory), some large-capacity memory (disk) and a variety of other components, through a set of cables called the bus to connect all these, the transmission of information between the parts.

2, Intel duo Core 2.1GHz means: This CPU is manufactured by Intel, an integrated circuit chip has two CPUs, "nuclear" is the meaning of the processor. The speed of the CPU is largely measured by the number of operations performed per second, the number of instructions, or the number of actions that are smaller. "2.1GHz" means that the CPU beats 2.1 billion times per second.

3, the main memory, that is, random access memory (RAM, that is, memory), which holds the processor and other parts of the computer is actively using information.

Not only does the memory store the data that the CPU is processing, it also saves the instructions that the CPU needs to perform to handle the data.

Memory is referred to as "random access" because the CPU can quickly access information from anywhere in the same speed. Speed is unaffected by any sequential access to different locations.

4, solid-state disk (SSD), using flash memory instead of rotating mechanical parts. The information in the flash memory is stored as an electric charge in the circuit, and the charge on each circuit element is not required to be power-up to maintain its state and is non-volatile.

Second, bit, byte and information representation

1. The computer is a digital processor that stores and processes discrete information rather than analog information.

The computer uses BITS to represent information, and the larger information is represented by a bit group.

2. Simulation refers to the smooth change with other factors, that is, the change process is not interrupted. The digital system deals with discrete values: the possible values are limited.

Compared with analog system, digital system has two advantages: first, digital data can be stored, transmitted and processed in many ways, and second, it is easier to expand.

third, in-depth understanding CPU

1, the CPU is the brain of the computer, it can make a decision, and also according to the data he processed to decide what to do next, so it can run the entire system on its own.

2, the typical CPU has dozens of to hundreds of different instructions; instructions and data typically occupy multiple memory locations, typically 2 to 8 bytes. A real processor has multiple accumulators, usually 16 or 32, so you can save multiple intermediate results, all of which are extremely fast memory.

3, in the CPU, the cache is a small but fast memory, used to store the most recently used information to avoid access to ram.

4, the typical CPU has two to three caches, the capacity is increased sequentially, but the speed is reduced, generally referred to as a first-level cache, two-level cache, three-level cache.

5, the idea of caching everywhere, multiple accumulators in the CPU is essentially a cache, RAM can also be used as a disk cache, and RAM and disk can be used as a cache of network data.

Although learning computer, but not much knowledge of the computer, by reading this book on the hardware part of the introduction of the computer configuration has a more profound understanding, at least when the computer to see the parameters of the computer to know what he said. Compared to non-professional books, professional books to my harvest or more, I hope in the future I can become a computer experts ...

"The World Is Digital" (1/4)