Arithmetic unit and controller are collectively called central processing unit (CPU).
Memory is divided into internal memory and external memory.
CPU, memory and interfaces connecting input and output devices are collectively referred to as the host. The host of the microcomputer is integrated on the motherboard.
External memory, input devices and output devices are collectively referred to as external devices.
cpu
The central processing unit of a computer, also called CPU, is the core part of the computer. It is mainly composed of arithmetic unit and controller.
Arithmetic unit: A component that performs arithmetic and logical operations.
Controller: the command system of a computer. The controller accesses the memory through the address, takes out the instructions from the memory, and generates corresponding operation control signals to act on other components according to the analysis results of the instructions by the decoder, so that all components work in an orderly and coordinated manner under the control of the controller.
Instruction: A command that instructs a computer to perform various operations.
Instruction system: the collection of all instructions of a computer.
Execute the four basic operations of the instruction:
The CPU of microcomputer, also called microprocessor, can be updated quickly;
4004 → 8008 → 8080 → 8088 → 80286 → 80386 → 80486 → 80586 → Pentium II → Pentium III → Pentium IV → …
The performance index of CPU depends on the clock frequency (main frequency) and word length.
Main frequency refers to the clock frequency of CPU. The higher the main frequency, the faster the computer runs. The main frequency of Pentium III can reach above 866MHz, and Pentium IV can reach 2.6GHz and 2.8GHz.
Word length refers to the length of a word. The longer the word length, the wider the range of digital representation. Under the same clock frequency, the higher the operation accuracy and the faster the operation speed. The word length of microcomputer has experienced four generations of changes: 4-8-32-64.
Storage mechanism of computer
Memory is a memory component used to store all data and programs in a computer. Its basic function is to store (write) information or obtain (read) information at a specified address.
The memory in a computer can be divided into two categories: one is memory, which is called main memory for short; The other is external memory (auxiliary memory), which is called external memory or auxiliary memory for short.
The memory consists of several memory cells, each of which has an address, and the computer reads and writes the memory cells through the address.
The number of bytes contained in a memory is called storage capacity, and the units are B, KB, MB, GB, TB, etc.
1 B = 8 bits (1 byte = 8 bits)
1 KB = 1024 B
1 MB = 1024 KB
1 GB = 1024 MB
1 TB = 1024 GB
Storage mechanism of computer memory
Memory: used to store programs or data currently in use or needed at any time, including ROM and RAM. Main features: fast access, small capacity and high price.
Read only memory. Features: only read, not write; Information will not be lost after power failure. It is mainly used to store fixed basic input and output programs.
Random access memory. Features: readable and writable; But all the information was lost after the power cut.
The size of microcomputer memory capacity generally refers to the size of RAM. At present, the common memory configurations of microcomputers are 64MB, 128MB, 256MB or 5 12MB.
Storage mechanism of computer external storage
External memory: used to store programs or data that are temporarily unused or need to be saved. When the information in the external memory needs to be used, it must be transferred to RAM for execution and processing by CPU. Main features: slow access, large capacity and low price.
The external memory of microcomputer generally includes floppy disk, hard disk and CD.
Floppy disk storage (floppy disk for short): consists of floppy disk, floppy disk driver and floppy disk driver card. Microcomputer generally uses a 3.5-inch floppy disk with a capacity of 1.44MB. Note: the write protection port on the floppy disk is a device to protect the data on the floppy disk.
The information stored on floppy disks is organized and stored by tracks and sectors. Tracks are concentric circles with different perimeters, but they store the same amount of data. Each track is divided into several sectors on average, and each sector can store several bytes. The number of sectors and bytes is determined by the formatter.
Format: Divide the disk into tracks and sectors, and write the address tag of each sector. The formatted disk produces four areas: boot area, file allocation table area, file directory area and data area.
Write protection gap: controls the reading and writing operation of floppy disk.
Calculation of floppy disk capacity: number of bytes/sector× sector/track× track/surface× surface.
Hard disk storage (hard disk for short): consists of hard disk and hard disk drive. Hard disk organizes and stores information in the format of cylinder, head number and sector number. The cylinder is a concentric circular cylinder composed of a group of disks with the same tracks in the longitudinal direction, and the division of each track and sector on the cylinder is the same as that of the disks. The hard disk is enclosed in a metal body, and the position of data on the hard disk is determined by three parameters: cylinder number, head number and sector number. The hard disks commonly used in microcomputers are 10GB, 20G, 30G, 40G, 60G, 80G, 100G, 120G, etc.
CD-ROM drive: It consists of CD-ROM drive and CD-ROM drive. At present, there are mainly three types of optical discs: CD-ROM, write-once optical disc and erasable optical disk. The capacity of 5.25-inch optical drive is 650 MB ~ 1 GB.
Input device of computer
An input device is a device that inputs information (programs, data, sounds, words, graphics, images, etc.). ) enter the computer. Common input devices in microcomputers are: keyboard, mouse, graphic scanner, touch screen, bar code input device, light pen, etc. External memory is also an input device. diagrammatic presentation
keyboard
The mouse can be divided into electromechanical mouse and photoelectric mouse according to its structure.
Output device of computer
Computer output devices mainly include monitors, printers and plotters. External memory is also an output device.
There are many kinds of displays, including cathode ray tube display, liquid crystal display and plasma display, which are divided into 14 inch, 15 inch, 17 inch and 17 inch flat panels. The content on the display consists of pixels, and the sum of pixels is the resolution; Common high resolutions are: 640 * 480/1024 * 768/1280 *1024; The higher the resolution, the better the definition. The interface between the monitor and the host is a graphics card. Common graphics cards are VGA and SVGA. The number of colors supported by a color graphics card is an important indicator of the graphics card, which mainly depends on the size of the memory RAM.
For example, the resolution is 320×200, and each pixel needs to display four colors. From 22=4, it can be seen that each pixel color occupies 2 bits, and * * needs 2×320×200= 16000B of memory.
Common printers are: needle printer, laser printer and inkjet printer.
Other parts of the computer
Motherboard: Microcomputer adopts "building block" architecture. Motherboard is a printed circuit board with multiple rectangular slots. CPU, memory, graphics card, multi-function card and so on can be inserted into the motherboard. The multi-function card has a serial port (for connecting a mouse) and a parallel port (for connecting peripheral devices such as printers). In addition, the sound blaster card, video card and modem will also be plugged into the motherboard.
Interface: I/O interface circuit is an essential component for information conversion and buffering between microprocessor and external equipment.
Bus is a set of public signal lines connecting all parts of microcomputer, and it is a common channel for transmitting data and information in computer. According to different transmission information, buses are divided into address bus (AB), data bus (DB) and control bus (CB).