Computer Information Technology and Computer Culture
Information Representation in Computers
Number system and its conversion
Number system: use the principle of carry to count Numbers: different digital symbols representing the basic value in the number system Base: the number of numbers used in a number system Digital weight: the weight of the number in different positions
number conversion
• R base to decimal number conversion
• Conversion from decimal to R-ary
• Binary to octal
• Octal to binary
• Convert between binary and hexadecimal
• Note: Some decimal numbers cannot be accurately converted in binary, octal, and hexadecimal
encoding of information
unit of data in a computer
• bit
• Shorthand: b, called bit, is the smallest unit of data stored in a computer
• Byte
• Shorthand: B, 1B=8bit. Byte is the basic unit of storing information
• B<KB<MB<GB<TB
• Word (Word)
• When the computer performs data processing, the CPU accesses the data at one time through the data bus, and the processed and transmitted data is called word
• A word usually consists of one byte or several bytes, depending on the performance of the CPU (32-bit, 64-bit)
• word length
• Word length is the number of bits of binary data that a computer can process simultaneously
• Since the word length is the number of bits of binary data that a computer can process simultaneously, the word length is an important indicator of computer performance
numerical representation
• It is usually stipulated that the highest bit of a number is the sign bit, 0 means positive, 1 means negative
• Machine number: the data coded together with Unicom numerals in binary form. In order to correspond to the commonly used decimal system more quickly and intuitively in computer input and output operations, the encoding method of using four binary numbers to represent a decimal number is called For BCD code, or 8421 code
• Western character encoding
• ASCII code (American Standard Code for Information Interchange) ASCII code is a Western machine internal code (the highest bit is 0)
• Standard ASCII code
• One byte represents one character, 7 digits, and can represent up to 128 different characters
• Extended ASCII code
• One byte represents one character, 8 digits, and can represent up to 256 different characters
• Chinese character encoding
• Chinese character exchange code (the highest bit is 0) ---- national standard code
• 2 bytes (16 binary bits) represent a Chinese character my country's first Chinese character exchange code standard GB2312-80, referred to as the national standard code GBK is also a Chinese character exchange code
• Chinese character machine internal code (the highest bit is 1)—internal code
• In order to distinguish between ASCII code and Chinese characters, when expressing Chinese characters inside the computer, the highest bit of the two bytes of the exchange code (national standard code) is changed to 1, which is called the internal code
• Chinese character font code (not unique) – output code
• All the different fonts and font sizes of the graphic data needed to display Chinese characters on the screen or print them on paper constitute the Chinese character library
• Dot matrix code
• Vector code
• Chinese character input code - foreign code
• Coding rules should be easy to accept, learn, memorize and master, less repetitive codes
• According to the coding rules, Chinese character input codes can be divided into serial codes, phonetic codes, graphic codes, and phonetic-shaped codes. According to the characteristics of Chinese characters: Chinese character input codes can be divided into phonetic codes, graphic codes, and phonetic-shaped codes
• Image representation
• Image digitization
• sampling
• find pixels
• quantification
• Assign values to pixels
• coding
• The process of converting sampled and quantized data into binary code 0s and 1s
• Image parameters
• Color model
• RGB (Red Blue Green)
• Desktop
• CMYK (cyan, magenta, yellow, black
• Color printing, printing industry
• YUV (luminance, chrominance)
• Color TV signal transmission
• Image Resolution
• In the process of image digitization, image scanning is divided into mxn pixels, and the total number of pixels after sampling is called image resolution
• Number of bit planes
• Number of matrices, number of color components in the image model
• Color quality
• Also known as color depth or pixel depth, refers to the number of binary digits used to store each pixel, including 8 bits, 16 bits (64K colors), 24 bits (true color), and 32 bits
• image encoding
• Image data volume = horizontal resolution x vertical resolution x pixel depth/8 (unit, byte B)
• Classification of image coding methods
• Lossy encoding
• Lossless encoding
computer system
How computers work
instruction
• A command for a computer to perform certain operations, consisting of a string of binary codes, including an operation code and an address code
• opcode
• The opcode specifies the type of operation
• address code
• The address code specifies what address the operation object is stored in, and what address the operation result is stored in
• The set of all instructions is called the computer instruction set Different computer systems have different instruction sets
• Streamlined instruction set
• Complex instruction set
How Stored Procedures Work
• The basis for the computer to automatically complete the calculation or processing process is the working principle of "stored program"
• Basic idea
• stored procedures
• program control
• Despite the fourth generation of computers, the fundamentals of how they work have not changed
computer working process
• instruction fetch
• The controller fetches the instruction from the memory and sends it to the instruction register
• Analysis instructions
• Analyze the instruction stored in the instruction register, determine what operation to perform, and determine the address of the operand by the address code
• execute commands
• A series of control information required by the controller to complete the operation
• Instruction cycle: all three instructions are executed once, including several machine cycles Machine cycle: one of the three separate processes is a machine cycle
About Von Neumann
• Propose the principle of stored program control
• The basis of the computer's ability to automatically complete calculations or processing processes is the working principle of "stored programs"
• Two basic ideas
• stored procedures
• program control
• Divide computer hardware systems into five parts
• Input devices, output devices, calculators, controllers, memories
• Introduce binaries to computers
• Father of the modern computer
computer hardware system
input device
• Function: Convert raw data and programs that process the data into binary codes that computers can understand
• Mouse, keyboard, scanner, digitizer, pen tablet, digital video camera, strip reader, A/D converter
output device
• Function: Convert internal information such as data and calculation results processed by computers into information forms that people are accustomed to accepting
• Monitors, printers, stereos, plotters, D/A converters
• From the perspective of information input and output: disks, touch screens, tape drives, storage, and disk drives can be regarded as both input devices and output devices
calculator
• Composition: arithmetic logic operation unit (ALU) + instruction register
• Function: perform arithmetic and logical operations
controller
• Function: The controller is the control center of the entire computer system, directing all parts of the computer to coordinate their work. The controller sequentially fetches instructions from the memory, translates the instruction codes, and then sends out corresponding commands to each component
• Central processing unit (CPU) = controller + arithmetic unit
memory
• Memory
• Read Only Memory (ROM)
• Features: fixed program, not modifiable, data will not be lost when power off, small capacity
• BIOS (Basic Input Output System)
• Power-on self-test and initialization, program service handling and hardware interrupt handling
• Random access memory (RAM)
• Features: information can be read and written, information lost when power off, storage of running programs and data
• CMOS
• Store the real-time clock information of the computer system, hardware configuration information, etc., powered by the system power supply and backup battery
• cache
• Coordinate CPU and memory speed differences
• Computers process data and execute commands from memory
• External storage (external storage, secondary storage)
• Can exchange information with memory in batches
• Cannot exchange information directly with CPU
the host
• CPU
• Memory
peripherals
• input device
• output device
• external storage
computer software system
information in the computer
• Software: program + data + related documents
• Program: A sequence or collection of computer instructions designed to solve a specific problem
System software: software for managing, monitoring and maintaining computer resources, and developing application software, which resides in the layer closest to the hardware of the computer system
• operating system
• An operating system is a collection of systematic programs that control and manage computer resources
• The operating system is the most basic system software that runs directly on the bare metal
• language handler
• Source programs written in various programming languages cannot be directly executed by computers and need to be translated. These translation programs are language processing programs
• type
• Assembler
• Compiler
• Translate a source program written in a high-level language into its equivalent machine language
• interpreter
• Translating and executing the source program without generating an object program
• Execution speed: compiled language system > interpreted language system
• System support and service programs
• System diagnostic program, debugging program, troubleshooting program, editing program, anti-virus program
• Database management system
application
• Anti-virus software, communication software, etc.
programming language
• Program = algorithm + data structure
• Characteristics of the algorithm
• Finiteness
• Certainty
• Feasibility
• Entry
• output item
• type
• machine language
• The only computer can recognize do not translate, directly for computer use
• Program writing is difficult, poor intuition, and error-prone
• Due to the different command systems of different computers, it may not be able to run on another computer, and the versatility and portability are poor
• Write programs in machine language to fully utilize the features of hardware functions
• Assembly language
• Symbolic machine language, using mnemonics instead of opcodes and symbols for operand addresses
• Easier to read than machine language, but still a machine-oriented language, dependent on specific machines
• Machine language and assembly language are called low-level languages
• high-level language
• The details of the shielding machine have nothing to do with the specific computer instruction system, and the expression is close to human understanding
microcomputer system
Key performance indicators of a computer
• Main frequency: the number of pulses issued by the computer CPU per unit time
• Word length: refers to the number of bits of binary data that a computer can process simultaneously
• number of cores
• The introduction of multi-core processing technology greatly improves the multi-tasking performance of the CPU
• Memory Capacity
• Refers to the total number of bytes of information that can be stored in memory
• access cycle
• The smaller the access cycle, the faster the operation speed
• calculating speed
• Number of computer instructions executed per unit time
• MIPS
• 106 instructions per second
• BEEPS
• 109 instructions per second
Hardware equipment of common microcomputers
• Microprocessor
• Ultra-large-scale inheritance circuit chip integrating arithmetic unit, controller, and cache memory
• memory
• Internal memory
• Memory seeking in computers is generally referred to as random access memory (RAM)
• External storage
• The external memory has large capacity, high reliability and low price, and can store information permanently after power failure
• type
• optical storage
• Optical disk
• Semiconductor memory (flash memory)
• U disk
• disk
• hard disk
• The hard disk is the most important external memory on the computer
• Non-hard disk files do not enter the recycle bin
• Diskette
• Tape
• Common bus standards for computers
• The common communication backbone for the transfer of information between the various functional components of a computer
• Generally divided into data bus, address bus and control bus
• Motherboard
• The motherboard is the largest circuit board in a microcomputer system, sometimes called the motherboard or system board, and is a large printed circuit board (PCB) with various sockets
• input device
• Input/output (I/O) devices are tools for computer systems to communicate with the outside world
• Mouse and keyboard are the basic input devices
• output device
• display system
• The display system is the most basic and necessary output device for microcomputers
• He includes monitors and display adapters (also known as graphics cards)
• Performance
• display resolution
• Color quality
• refresh rate
• printer
• Dot matrix printers
• Noisy, monochrome printing, good for printing invoices
• Inkjet Printers
• laser printer
• High-speed, high-precision, low-noise non-impact printer
• Highest print quality and fastest print speed
• Expansion: bus
• Data Bus
• The data bus is bidirectional, and the specific direction of transmitting information is controlled by the CPU
• The width of the DB determines the number of bits per exchange of data between the CPU and other components of the computer
• the word length
• Address bus
• Used to transmit address information. usually one way
• If the address bus is n bits, then the nth power byte of bit 2 of the addressing space corresponds to these storage units
• Control bus
• Used to transmit control signals to coordinate the operation of various components
• Public transport trunks for information transfer from various functional components in the computer
Introduction to Computer Technology
origin
Charles Babbage first proposed the basic design idea of a general-purpose digital computer, known as the father of computers
When: 1946
The first electronic computer computer: ENIAC
Location: USA
How it works: Non-stored-program controlled computers
Using decimal calculation, no keyboard, no mouse, no memory
develop
Four Modernizations
• miniaturization
• Miniaturized volume
• Jumbo
• Faster, more powerful, and smaller
• Networking
• intelligent
two poles
• miniaturization
• Jumbo
features
Da Luo is proficient in sports
• Large storage capacity
• Have logical operation ability
• High calculation accuracy
• Strong versatility
• Fast calculation speed
• Job automation
Classification
According to processing object
• Analog computer, digital computer, hybrid computer
According to use
• special purpose computer, general purpose computer
Divide by size
• Supercomputers, Mainframes, Minicomputers, Microcomputers, Workstations
Application field
Scientific Computing (Numerical Computing)
• Mainly used in spaceflight, meteorology, earthquake, nuclear energy technology, oil exploration, password interpretation and other fields that require complex calculations
Information Management (Data Processing)
• Based on computer technology, process a large amount of data to form useful information
• Data processing in non-numeric form
• Office automation, transaction processing, information retrieval, enterprise management and knowledge systems, etc.
Process control (real-time control)
• in process
• automated industry
computer aided system
• CAD
• Computer Aided Design
• CAM
• Computer Aided Manufacturing
• CAI
• Computer Assisted Instruction
• CBE
• Computer Assisted Education
• CMI
• Computer management teaching
• CAT
• Computer Aided Testing
• PEAKS
• Computer Integrated Manufacturing System
artificial intelligence
• Robotics, speech recognition, image recognition, natural language processing, expert systems
development trend
Four Modernizations
• Megalization: Faster, more storage, more powerful
• Miniaturization: Smaller size
• Networking
• intelligent
two poles
• Jumbo
• miniaturization
Information and Information Technology
information and data
Information: information is the attribute of all substances and things
data: symbolic data to be identified
difference and connection
• Data is the specific form of information, the carrier of information, and the symbolization of information. Information is the result of data processing.
information Technology
Information technology refers to the technology of developing and utilizing information resources
In modern information processing technology, sensor technology, computer technology, communication technology, and network technology are the leading technologies, among which the computer plays a leading role. It is first of all an information processing machine.
information society
Information highway: high-speed, large-capacity, multimedia information transmission network
National Information Infrastructure: NII, proposed by the U.S. government
computer culture
In the early 1980s, computer culture was widely accepted
Cultivate people with computer information processing ability