linux--first chapter--Introduction to Computer

Introduction to Computers

Computer: " accept the user input instruction and data, through the processing of mathematical and logical units of the central processing unit, to produce or store into useful information."

Central processing Unit, CPU,CPU is a chip with a specific function, it contains micro instruction set

The CPU can be divided into two main units, namely: arithmetic logic unit and control unit, in which the arithmetic logic unit is mainly responsible for the program operation and logic judgment, and the control unit mainly coordinates the work between the peripheral components and the units.

The data that the CPU reads is from the main memory! As for the data flowing in/out of memory is the control command issued by the CPU!

The CPU actually already contains some small instruction set, we use the software to go through the CPU internal Micro instruction set to achieve. The design of these instruction sets is mainly divided into two design concepts .

This is the two main types of CPUs that are commonly found in the world: simplified instruction set (RISC) and complex instruction set (CISC) systems

1. Simplified instruction set (reduced instruction set computer, RISC)

In this kind of CPU design, the micro instruction set is more concise, the execution time of each instruction is very short, the completion of the action is very simple, the execution efficiency of the instruction is better; but to do something complex, it is done by multiple instructions . Common RISC Micro-instruction set CPU mainly such as Sun Company's SPARC series , IBM Company's Power Architecture (including PowerPC) series, and Arm series .

On the application side, the SPARC architecture computer is commonly used in large-scale workstations in the academic field , including the main servers of the banking financial system, as well as such computer architectures, and for applications such as the PowerPC architecture, such as the play Station 3 produced by Sony. (PS3) is the cell processor using the PowerPC architecture; what about arm? You often use the brand of mobile phones, PDAs, navigation systems, network equipment (switches, routers, etc.), almost all of the CPU using ARM architecture Oh! Frankly speaking, the world's most widely used CPU is probably arm!

2. Complex instruction set (Complex instruction set computer, CISC)

Unlike RISC, CISC each small instruction in the micro-instruction set can perform some of the lower-order hardware operations, the number of instructions is many and complex, the length of each instruction is not the same. Because instruction execution is more complex, each instruction takes a long time, but each individual instruction can handle a richer amount of work. Common CISC micro-instruction set CPU mainly has AMD, Intel, via and so on x86 architecture CPU.

The x86 architecture, developed by Intel before 2003, was upgraded from 8-bit to 16, 32-bit, and later AMD modified the next generation of CPUs to 64-bit, in order to differentiate between the two, so the 64-bit PC CPU is collectively referred to as the x86_64 architecture Oh, whoa!

Example: In the latest Intel/AMD x86 architecture, check out what are the important micro-instruction sets for multimedia, virtualization, and power-saving functions? (for reference only) A: multimedia micro-instruction set: MMX, SSE, SSE2, SSE3, SSE4, AMD-3dnow! Virtualization Micro-instruction set: Intel-VT, amd-SVM power Saving: Intel- SpeedStep, amd-powernow! 32-bit compatible technology: AMD-AMD64, INTEL-EM64T

The most important peripheral equipment is the motherboard ! Because the motherboard is responsible for all the devices are connected together, so that all the equipment can be coordinated and communication. the most important component on the motherboard is the motherboard chipset ! This chipset can bring together all the devices

Classification of computers:

• Super Computer (supercomputer): Defense Military, meteorological prediction, space science and technology, used in the field of simulation more. Details can also be consulted: National high-speed network and Computing Center HTTP://WWW.NCHC.ORG.TW Introduction! For the world's fastest top 500 supercomputers, please refer to: http://www.top500.org.
• Mainframe computers (Mainframe computer): The mainframe of large enterprises, national stock exchanges and so on every day to deal with millions of of data of enterprise organizations, or large enterprises database server and so on.

• Mini computer (minicomputer): Scientific research, engineering analysis and plant process management.

• Workstations (Workstation): very common in academic research and engineering analysis.

• Micro-computer (microcomputer): can also be called personal computers, roughly can be divided into table-type, note-type and so on

3. Capacity Unit

The computer does not have power to record information, so theoretically it only knows 0 and 1. 0/1 of units we call bit,

1 Bytes = 8 bits

1 gbytes File size: 1024x1024x1024 Bytes

4. Speed Unit

The speed unit is often used in 10 , e.g. 1GHz is 1000x1000x1000 Hz

The CPU often uses MHz or a unit such as GHz, which is actually one of the seconds. In the network transmission aspect, because the network uses bit as the unit, therefore the network commonly uses the unit to be Mbps is Mbits per second, namely is how many Mbit per second. For example, we often hear the 8m/1m ADSL transmission speed, if converted into a file capacity of byte, in fact, the theoretical maximum transfer value is: 1mbyte/per second 125Kbyte upload/download capacity Oh!

Example: Suppose you bought a 500GB hard disk today, but after the format has been left only about 460GB of capacity, what is the reason? A: Because the average hard drive manufacturer uses a decimal unit, the 500GByte represents the meaning of*1000*1000*1000Byte . The capacity unit of the file is converted to binary (base 1024), so it becomes about 466GB capacity . Hard disk manufacturers are not to deceive, just because the minimum physical capacity of the hard disk is 512Bytes, the smallest component is the magnetic region (sector), usually the hard disk capacity of the calculation using "How many sector", so it will be used to deal with the decimal. The relevant hard drive information will be mentioned later in this chapter! 

linux--first chapter--Introduction to Computer