What is the function of the computer host?

What are the basic components of a computer host? What are the functions of various components?

Monitor, motherboard, memory, hard disk, CPU, graphics card, CD-ROM drive, floppy drive, chassis power supply, keyboard and mouse.

More specifically:

1 hardware system:

The hardware system of a computer consists of an input device, a host and an output device. External information is input to the host through the input device, analyzed, processed and processed by the host, and then output through the output device.

# 1 input/output devices:

Computers can only recognize binary digital electrical signals, while people are used to receiving graphics and audio-visual signals. Input and output devices play the role of signal conversion and transmission.

We often use keyboard to input text, microphone to input sound, digital camera, scanner and camera to input images.

Common output devices are monitors, printers and speakers.

# 1 motherboard:

Also known as motherboard, it is a rectangular circuit board installed in the mainframe case, on which the main circuit system of the computer is installed. The type and grade of the motherboard determines the type and grade of the whole microcomputer system, and the performance of the motherboard affects the performance of the whole microcomputer system.

The motherboard is equipped with a control chipset, BIOS chips and various input and output interfaces, keyboard and panel control switch interfaces, indicator light connectors, expansion slots and DC power connectors.

CPU and memory stick are inserted into the corresponding slots (seats) of the motherboard, and hardware such as drivers and power supplies are connected to the motherboard.

The interface expansion slot on the motherboard is used to insert various interface cards, which expands the functions of the computer. Common interface cards include video cards and sound cards.

# 1 CPU:

CPU (Central Processing Unit) is the core of computer, and the ability and speed of computer processing data mainly depends on CPU.

Usually, the capacity and speed of CPU are evaluated by bit length and main frequency. For example, the Pⅱ300 CPU can process binary data with a bit length of 32 bits, and the main frequency is 300MHz.

# 1 system bus:

The system bus is the information path connecting the expansion slot.

ISA and PCI bus are commonly used system buses in PC at present, and there are corresponding ISA and PCI slots on the motherboard.

# 1 input/output interface:

I/O interface, referred to as I/O interface, is the interface connecting the motherboard and input/output devices. The serial port, parallel port, keyboard interface, PS/2 interface and USB interface on the back of the host, and the hard disk and floppy drive interface inside the host are all input and output interfaces.

# 1 serial communication interface (RS-232-c):

The abbreviation of serial port is the standard interface for transmitting information between computers and other devices. At present, computers have at least two serial ports, COM 1 and COM2.

# 1 parallel communication interface:

Short for parallel port, it is the standard interface for computer to transmit information with other devices. The interface simultaneously transmits 8-bit data in parallel. The data transmission speed of parallel port is faster than that of serial port, but the transmission distance is shorter.

The parallel port uses a 25-hole D connector, which is usually used to connect printers.

# 1 EIDE interface:

Also known as the extended IDE interface, it is an interface for connecting EIDE devices on the motherboard. Common EIDE devices are hard disk and optical drive. At present, the newer interface standards are Ultra DMA/33 and Ultra DMA/66.

# 1 AGP:

That is, "accelerated graphics port" is a graphics card interface standard proposed by Intel in July 1996, which connects AGP graphics cards through AGP slots on the motherboard. The transmission speed of PCI bus can only reach 132MB/s, while the transmission speed of AGP port can reach 528MB/s, which is four times of the former.

AGP technology greatly improves the performance of graphic display (especially 3D graphics), which makes PC take a big step forward in graphic processing technology.

# 1 optical disk drive:

A device that reads optical disc information. It is an indispensable hardware configuration for multimedia computers.

CD has large storage capacity, low price and long storage time, and is suitable for storing a large amount of data, such as audio, images, animations, video information, movies and other multimedia information.

There are three kinds of optical disk drives, CD-R, CD-R and MO. CD-R is a read-only optical disk drive. Cd-r can only be written once and cannot be rewritten later; MO is a writable and readable optical disk drive.

# 1 internal memory:

Memory for short, a semiconductor chip used to store information to be processed and common information. Small capacity, but fast access.

Memory includes RAM, ROM and cache.

# 1 memory:

RAM (Random Access Memory) is the main memory of a computer, and people are used to calling it memory. The biggest feature of RAM is that data will be lost when it is turned off or powered off.

The larger the memory of a computer, the more information it can process at the same time.

We use refresh time to evaluate the performance of RAM, and the unit is ns. The shorter the refresh time, the faster the access speed.

The RAM commonly used in 586 computer includes EDO RAM and SDRAM, and the memory chip is installed on a finger-wide strip circuit board, which is called memory stick. The memory module is installed in the memory module slot on the motherboard.

There are 30 lines, 72 lines and 168 lines according to the connection mode between the memory module and the motherboard.

At present, SDRAM memory chips with 168 lines, 10ns refresh time and 32M (or 64M) capacity are generally installed.

# 1 cache:

Cache is a small and high-speed memory located between CPU and main memory.

Because the speed of CPU is much higher than that of main memory, it takes some time for CPU to access data directly from memory. A part of data just used or recycled by CPU is stored in the cache, which can be directly called from the cache when the CPU is used again, thus reducing the waiting time of CPU and improving the efficiency of the system.

Caching is divided into first-level cache (L 1 cache) and second-level cache (l 2 cache). L 1 cache is integrated in the CPU, and L2 cache is generally welded on the motherboard. Ordinary motherboards are soldered with 256KB or 5 12KB L2 cache.

# 1 ROM:

ROM (Read Only Memory) is a semiconductor chip that stores computer instructions and data, but data can only be read from it, not written. ROM data will not be lost after shutdown or power failure.

Manufacturers store some important information and programs in ROM that users are not allowed to change, such as BIOS programs stored in ROM of motherboard and graphics card.

# 1 BIOS:

BIOS is a program, that is, the basic input and output system of microcomputer. The main function of BIOS program is to manage the hardware of computer.

The BIOS program is the first program when the computer is started. After booting, the BIOS program first detects the hardware, initializes the system, then starts the driver, reads the boot record of the operating system, hands over the system control to the disk boot record, and the boot record completes the system startup. When the computer is running, BIOS also cooperates with the operating system and software to operate the hardware.

The BIOS program is stored in the ROM BIOS chip on the motherboard. At present, most 586 motherboards use Flash ROM to store BIOS programs, and running programs can update programs (data) in Flash ROM.

# 1 CMOS:

CMOS is a read-write RAM chip on the motherboard, which is used to store the hardware configuration information of the current system and some parameters set by users. CMOS RAM is powered by the battery on the motherboard, so even if the system is powered off, the information will not be lost. To set and update various parameters in CMOS, you need to run a special setup program. At startup, you can set CMOS by entering the BIOS setup program through a specific key (usually Del key). CMOS settings are also called BIOS settings.

# 1 graphics card:

Also known as the display adapter card, it is an interface card that connects the host and the display. Its function is to convert the output information of the host computer into text, graphics, colors and other information, and transmit it to the display for display.

The graphics card is inserted into the expansion slots of ISA, PCI and AGP of the motherboard, and the ISA graphics card has been basically eliminated.

# 1 sound card:

An interface card for processing sound in a multimedia computer.

A sound card can convert the sounds and music from microphones, tape recorders, CD players and other devices into digital signals, which are handed over to a computer for processing and saved in the form of files. It can also restore digital signals to real sound output. The interface on the back of the sound card extends from the back of the chassis, and there are interfaces for connecting microphones, speakers, joysticks and MIDI devices.

# 1 video capture card:

Interface cards used to capture dynamic or static video images input from TV antennas, video recorders and DVD players are important tools for multimedia production. Advanced video capture card can also capture images while compressing MPEG to make VCD.

# 1 Interrupt:

Interrupt is the process of computer dealing with special problems. When a special situation (or "event") occurs in the process of computer executing a program, the whole process of temporarily suspending the current program, switching to the program executing the event, and returning to the breakpoint of the original program to continue execution after processing is called interruption.

# 1 IRQ:

In other words, an "interrupt request" is a signal sent by other devices requesting a computer response. The computer will decide when to respond according to the level and priority of IRQ. In principle, each device has its own unique interrupt request channel, that is, IRQ value (also called IRQ number). If two hardware devices use the same interrupt channel, an IRQ conflict will definitely occur.

# 1 DMA:

That is, "direct memory access" is a data transfer operation in the computer. The whole data transmission operation process is carried out under the control of "DMA controller" without CPU. During data transmission, CPU only does a little processing at the beginning and end of data transmission. DMA technology greatly improves the efficiency of computer system.

DMA transmission is carried out through DMA channel. For example, floppy drives and sound cards occupy DMA channels to transfer data. Two devices cannot transmit data on the same DMA channel at the same time, otherwise DMA conflicts will occur.

# 1 Main frequency and external frequency:

The main frequency refers to the working clock frequency of the CPU core. External frequency refers to the working clock frequency at which CPU exchanges data and instructions with the outside (motherboard chipset).

The system clock is the "external frequency" of the CPU, and the clock signal obtained by multiplying the system clock by a specified ratio is the core working clock (main frequency) of the CPU. For example, if a computer uses Pentium 233 CPU, the external frequency of this computer is 66MHz, and its main frequency is (66×3.5)=233MHz.

System clock (external frequency) is the basic clock of computer system, and all clocks with different frequencies in each subsystem of computer are related to system clock. For example, in the current 100 MHz external frequency system, the system memory works at 100 MHz (or 66MHz), L2 cache works at 100 MHz, PCI works at 33MHz, and AGP works at 66MHz. It can be seen that all the above frequencies are directly proportional to the external frequency.

Increasing the system clock (external frequency) can improve the performance of the whole computer, but increasing the external frequency will inevitably change the clock frequency of other subsystems and affect the actual operation of each subsystem, which should be paid full attention to when the CPU runs beyond the external frequency.

# 1 DVD:

The digital versatile disk. A DVD drive refers to a device that reads DVD discs. The capacity of DVD is 4.7GB, which is 7 times that of CD-ROM. It can store 133 minutes of movies, including seven dolby digital orbits. DVD discs can be divided into: DVD-ROM, DVD-R (write once), DVD-RAM (write many times) and DVD-RW (read and rewrite).

At present, most DVD optical drives use EIDE interface, which can be connected to IDE 1 or IDE2 port like optical drives.