Shulou(Shulou.com)06/02 Report--

Because the operating system is related to hardware to a considerable extent, it is difficult for bloggers to learn about the operating system if they do not understand the introduction to computers. Bloggers only spend a month learning and writing blogs. Some of the things I hope to sum up will be of some help to some friends who don't know much about computer principles. Refer to the book "Bird's linux Private Cuisine".

1. Computer development

1.1 、

In fact, the computer is: accept the user's instructions to the data, transport and process the data and logic units of the central processing unit, and finally produce effective information. So the original computer design was like this.

People input the information into the computer through the input device, and the computer processes the information through the central processing unit, and then tells you the results through the output device.

The world's first generation of computer "ENIAC" was born in 1946 at the University of Pennsylvania in the United States. At that time, the computer design was so poor that there were no convenient tools such as a mouse (Dr. Doug Engelbart) and a keyboard. At that time, the computer was still a big guy, covering an area of 170 square meters, as high as two stories. It can perform 5000 operations per second. People can only input information to the computer by flipping countless switches on the huge panel of the computer, and after the computer processes these information, the output equipment is also quite crude, that is, countless signal lights on the computer panel. So the computer at that time couldn't handle all kinds of information like it is now, and it could only do digital operations.

1.2 、

As the amount of data increases. People found that the original computer was already very difficult to calculate a large amount of data. So the original computer model is improved and an internal memory is added next to the CPU.

The computer flow changes to put the data of the input unit into memory, the cpu reads the data from memory, and the data processed by cpu must be written back to memory before the data is transferred from memory to the output unit. The comparison of the two models is equivalent to a math problem assigned by the teacher. In the past, you could only do it in your head, but now it provides you with a draft paper.

1.3 、

With the development of the times, people feel the backwardness of input and output equipment, so there is a paper tape machine. The paper tape machine works like this: each line of the tape is marked with 26 letters, 10 numbers and some arithmetic symbols. if there is a hole in the letter An of this line, it means that the letter An is to be typed here. Similarly, the next line may be the letter H, and the next line may be the number 1.

Such a long paper tape can replace a lot of information, people put this paper tape into the paper tape machine, and the paper tape machine has to translate the information on the paper tape to the computer, because the computer can not understand the paper tape.

Although it is still troublesome, this progress has indeed promoted the development of computers to a great extent.

While inventing paper tape, people have also improved the output system, replacing countless signal lights on the computer panel with printers. The function of the printer is just the opposite of the paper tape machine, which is responsible for translating the information output from the computer into a language that can be understood and printing it on paper. In this way, people can easily see the output information, and they no longer have to look at hundreds of signal lights.

1.4 、

However, people are not satisfied, they continue to improve the input and output systems. As a result, keyboards, mice and monitors appeared. As more and more data are entered. If there is a power outage, the initial data input will be wasted, so people add external memory to the original model. In this way, the power outage will not lose data.

This time the model goes like this.

2. Introduction to computer

From the above text, you may already have a model understanding of the computer. Let's take a look at the introduction to modern computers.

2.1 computer hardware

Simple add, subtract, multiply and divide calculators, mobile phones, GPS,ATM, desktop computers, notebooks, netbooks are all computers.

The computer consists of five units. It includes five parts: input unit, output unit, CPU internal control unit (coordinating the work of each component and each unit), algorithm logic unit and memory.

Motherboard (the most important interface device)

The motherboard is an important project that links various components, so that all devices can coordinate and communicate. The most important thing on the motherboard is the motherboard chipset, so communicating the chip design of each component on the motherboard will affect the performance. The early chips are divided into North Bridge and South Bridge to control the communication of various components.

North Bridge:

Responsible for linking faster CPU, main memory and display adapter interface and other components. Nanqiao: responsible for connecting slower device interfaces, including hard disk, USB. Network card, etc., but because the most important thing of Beiqiao is the bridge between CPU and main memory, most of the current mainstream architecture combines the Northbridge memory controller into CPU encapsulation, so that CPU will not consume more bandwidth when reading the actions of main memory. So the motherboard generally can not see the North Bridge, other CPU slots, memory slots we will not elaborate.

South Bridge:

Responsible for connecting busy peripheral interfaces, such as hard disk, USB, network card, etc.

The brass heat sink on the north bridge and the south bridge. And connected several circular ducts, just to dissipate heat (this is nonsense, )

So almost all chipsets are planned with reference to CPU, so buy CPU, motherboard, memory-related interface devices to reference data at the same time.

Some chips emphasize full function, so even graphics cards, sound effects, and networks are integrated. However, the performance of integrated chips is relatively weak. (video card, stand-alone video card)

Icano address and IRQ interrupt communication

The motherboard is responsible for the communication of computer components. However, there are many components, such as Ihammer O devices and different storage devices. In order to know how to communicate with each other, motherboard chips need an Imax O address and an IRQ. Therefore, it is not possible for two devices to use the same IZP O address. And IRQ interrupt. I am O can be thought of as a device door number.

IRQ is the special path for each house number to connect to CPU. The device can inform CPU of the operation of the device by interrupting the channel of the IRQ.

.

CMOS and BIOS

CMOS records the important parameters of the motherboard, such as system time, CPU voltage and frequency, and the IRQ of each device. BIOS loads the parameters of CMOS on boot and tries to call the boot program of the storage device. Further into the operating system. BIOS can modify the data of CMOS. We will also introduce CMOS and BIOS in the following memory.

When there is a built-in sound chip on the motherboard, there will be sound output and input into these circular jacks. PJ-45, when there is a built-in network chip, there will be this kind of connector similar to the phone interface. When the blogger used to repair the computer, he found that there were eight wires in it, and each wire had to be arranged in a certain order in order to be successful, and the size of the interface was different, but the order of the lines was the same.

CPU

CPU contains some small instruction sets, and the software we use has to go through the microinstruction set inside CPU. These instruction sets are divided into two types: reduced instruction set and complex instruction set. These are also the two main types of CPU.

Reduced instruction set (RISC)

The microinstruction of this kind of CPU is simplified, each instruction execution time is short, the operation is simple, the execution performance is good, and the complex things are accomplished by multiple instructions. SPARC's CPU is used for large workstations in the academic field, such as the main server of the banking and financial system. PowerPC's CPU, such as sony's Play Station3 (ps3), is the cell processor of powerPC architecture.

Complex instruction set (CISC)

Each small instruction in its microinstruction set can perform some lower-level hardware operations, and there are many and complex instructions, and the length of instructions is different, and the execution of instructions is more complex, so each instruction takes a long time. The CPU of the common CISC microinstruction set mainly has AMD,Inter,VIA and other x86 architecture CPU, while the most widely used processor in the world is Amou ARM, which is used in various brands of mobile phones, PDA, navigation systems, switches, routers and so on.

Because the x86 architecture CPU developed by AMD,Inter,VIA is widely used in personal computers, it is also called x86 architecture computer. (the earliest Inter developed the CPU code name 8086, and later developed 80286, 80386, etc.) so this kind of CPU is called x86 architecture. Before 2003, the x86 architecture CPU developed by Inter was upgraded from 8-bit to 16432-bit, and later AMD modified the architecture to 64-bit.

In addition to the overall architecture (the second layer cache, the number of instructions that can be executed per time, etc.), the CPU of different X86 architectures is mainly different in the microinstruction set. It is clear that the new architecture microinstruction set is advanced. It can accelerate the operation of multimedia programs, enhance the performance of virtualization, strengthen the energy effect, and reduce power consumption.

64-bit CPU can read and write so much data to 64bits at a time. , 1btye equals 8bitjiao 20m is 20Mbit/ seconds, different feed positions have different conversions, and 1k equals 1024kb 1024MB in binary 1k equals 1024kb 1024MB. Under the decimal system, 1k equals 1000b. File capacity is commonly used in binary, while the speed unit is in decimal.

When we bought a flash drive, 16g, but only 14g after formatting, is it unscrupulous? No! Because the factory capacity is a decimal algorithm, and the operating system commonly used binary algorithm. The minimum physical unit of a hard disk is 512bytes, and the smallest constituent unit is sectoe. Calculate how many sector are used through the capacity of the hard disk.

At present, the mainstream CPU is more than dual-core architecture, single core is only one computing unit multi-core is a CPU package embedded with more than two computing units, different CPU has different corners, so the matching motherboard chipset is also different, so mainframe upgrade can not only consider CPU, but also consider the CPU model supported on your motherboard.

The working frequency of CPU external frequency and internal frequency

Frequency is the number of jobs that can be done by CPUM per second. The speed unit of CPU is MHz or GHz (one second of HZ).

1GHZ means that you can work to the ninth power of 1 to 10 in one second. A small number of instructions can be run for each job.

CPU is the speed at which data is transmitted by CPU and external components. Multiplier is a multiple used inside CPU to speed up work, and the multiplication of the two is the frequency of CPU. (CPU requires powerful computing power in order to be consistent with the speed of external components, so an acceleration function is added in CPU, which is external speed and multiplier.)

Memory

All the data used by CPU comes from memory, whether it is software program or data, it must be read into memory CPU before it can be used. If the memory capacity is small, it will cause some large capacity data to not be fully loaded. At this time, the data that is not being used in memory must be released first, so that the memory capacity is larger than that data. That data can be loaded, usually the larger the memory runs faster, this is because the system does not often release some of the data inside the memory, for the server, memory capacity is sometimes more important than cp speed.

Dual channel design

Of course, the larger the data width of memory, the better. But the traditional width is usually 64 bits, in order to increase the width, the chip assembler merges the two pieces of memory together, so that it can reach 128 bits. This is the concept of dual-channel design. To enable the double pass function, you must install two (or 4) pieces of memory, and the best model is the same. Because the dual channel is enabled, the data is written and read synchronously, so that the overall bandwidth can be improved. So the capacity should be the same, and the model had better be the same.

Frequency of memory and cpu

In theory, the external frequency of cpu and memory should be the same. However, with the improvement of technology, the frequency of the two will not be the same, but the same is the best.

DRAM and SRAM

The data of CPU is provided in memory, and the data in memory is sent to CPU through the north bridge. If the commonly used data is put inside the CPU, then the data reading of the CPU does not need to go through the North Bridge. For a significant improvement in performance, this is the second layer caching concept. The second layer cache is integrated into the CPU, so the memory of L2 cache must be the same as the CPU frequency, which cannot be achieved with DRAM. At this point, you need static random access memory (SPAM) help. SRAM has a large number of crystals when it is designed. The price is high. It is not easy to make large capacity. But several times are fast, so it's a good way to integrate into CPU as a cache to speed up data access.

Read-only memory (ROM)

The frequency of CPU and memory is adjustable. If there is a built-in network card or graphics card on the motherboard, whether the function is enabled or not is recorded on a CMOS chip on the motherboard. The chip needs additional power to perform the recording function, which is why there is a battery on the motherboard.

Boot is to enter the BIOS (basic input output syatem) is a set of programs, this program is written to the motherboard memory chip, this chip can also record data when there is no power on. That's ROM. ROM is non-volatile memory. It's important for PC BIOS. Because it is the first Mini Program that the system will read when booting up. Many firmware also use ROM for software writing. Firmware, like software, is a program executed by a computer. It is important to get inside the firmware. Such as BIOS is a firmware, it controls the boot of the hardware parameters. So a lot of hardware has ROM on it to write firmware.

Computing is developing too fast. Therefore, the BIOS program code should also be modified appropriately. So there is an update for BIOS on the official website of the motherboard, but the original ROM used by BIOS cannot be modified. So it is impossible to modify the program code of BIOS at all. For this reason, BIOS is usually written to flash memory or EEPROM.

Video card

The memory capacity of the graphics card will affect your screen resolution and color depth. Saving memory is also important for some 3D animation computing power. Early 3D computing is for CPU, but CPU is not designed for 3D animation, and usually CPU is very busy green, so later video card vendors directly embed a 3D acceleration chip on the graphics card, which is the origin of the name CPU.

The graphics card also communicates with CPU memory through the Beiqiao chip. For graphics and images, the graphics card is also a component that needs to run at high speed, so the faster the data transmission, the better, so the specification is directed to AGP from the early PCI, and recently AGP has been replaced by the PCL-Express specification. PCLe is handled using a similar pipeline overview, where each pipeline can have the bandwidth performance of 250MB/s. The larger the pipeline (up to x32), the higher the total bandwidth. At present, most graphics cards use the x16 PCle specification, which can reach the bandwidth of 4GB/s, which is faster than AGP. The new PCle2.0 rule can double the performance of each pipeline.

Hard drives and storage devices

Storage devices on computer systems include hard disk, floppy disk, MO,CD,DVD, tape drive, U disk, etc., as well as local area network storage devices (SAN,NAS) for large machines

The hard disk consists of a disk, a robotic arm, a magnetic head and a main motor. The data is written on the disk with magnetic material, and the reading and writing is done through the reading head on the mechanical arm. In fact, the spindle motor makes the disk rotate. The robotic arm can then be extended to allow the reading head to read and write on the disk. In addition, due to the limited capacity of a single disk, there are more than two disks inside the hard disk.

There are many pie charts drawn by concentric circles on the disk, and the smallest storage unit of the disk radially divided by the center of the disk is the sector we mentioned above, and the sector forms a circle to become a track. If you are on multiple hard drives, the same track on all disks can form a cylinder, which is also the smallest unit in which we split the hard disk.

When calculating the amount of hard disk storage, the simple formula is the number of header x the number of cylinders each header is responsible for x the number of sectors contained in each cylinder x the capacity of sectors, unit conversion header X cylinder/header Xsecter/cylinderX512bytes/secter, of course, hard disk manufacturers also use the decimal algorithm.

Because of the transmission speed, the hard disk and host system mainly have IDE and SATA and SCSL transmission interface rules.

The IDE interface slot uses a wide array of cables, each of which can be connected with two IDE devices, in order to determine the master and slave architecture of the two devices. Therefore, the disk driver needs to adjust the jump pin to be the master and the slave, and the maximum transmission speed of this interface is Ultra 133specification. 133MB per second.

The SATA interface is much smaller than the IDE interface. Each SATA cable can only connect to one SATA device. SATA interface in addition to high speed, because of its fine wiring, so it is conducive to heat dissipation and installation, SATA-1 speed is 150MB per second SATA SATA-1 2 is 300MB per second, so the mainstream personal computer hard disk has been replaced by SATA. SATA is connected with one hard drive by one cable, so there is no need to adjust the jump pin. However, the number of SATA slots on a motherboard is not fixed, and each slot is numbered, so you need to pay attention when connecting the SATA hard drive to the motherboard.

SCSL interface

This kind of interface is common with the hard disk transfer interface above the level of workstation (described in the following computer classification). The hard disk of this interface contains a processor on the controller, which not only runs fast, but also does not consume CPU resources. this interface is not common on personal computers.

Buffer storage

There is a buffer memory on the hard disk, which can mainly buffer the data commonly used in the hard disk to speed up the reading performance of the system, usually the larger the buffer memory, the better. Because the speed of the buffer memory is much faster than the data is found from the hard disk.

Rotational speed

Because the hard disk is mainly accessed by rotating the disk surface of the spindle motor, the speed of rotation will affect the performance. The mainstream desktop computer hard disk is 7200 revolutions per second, notebooks are 5400 revolutions, some manufacturers will launch 10000 revolutions, there are high-performance data access requirements can be considered.

Operation instructions

The contact between the mechanical arm and head in the hard disk and the disk is very small space, if there is jitter or dirt between the disk and the hard disk, it will cause data damage, or the whole hard disk will be damaged. So to avoid moving the host, you can't just pull the plug and turn it off. Because the robotic arm has to return to its original position.

PCL adapter card

PCL slots are functional cards that provide users with additional needs. Such as network card, sound card special function card, because of the development of PCL-Express specification, many manufacturers forget to develop hardware with PCLe interface, but a lot of hardware still uses PCL interface, such as network card in supermarket. At present, the common network card in personal computer is Ethernet specification.

2.2 classified use of computers

1, supercomputer

2, mainframe computer

3, Mini computer

4, workstation

5. Microcomputer (personal computer)

At present, the speed of personal computers is very fast, even faster than computers such as workstations.

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