Introduction to Computer Systems Mind Map download link

I. Introduction to computer system

1. Computer hardware and software concepts

Computer system:

Hardware: The physical entity of a computer, such as a mainframe or peripherals. Software: consists of information (programs) with various special functions.

Software:

System software: Used to manage the entire computer system. (language processing program, operating system, service program, database management system, network software). Application software: various programs programmed according to task requirements.

2. The hierarchy of computer systems

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3. Computer architecture and computer composition

Computer architecture: The conceptual structure and functional properties of computer systems as seen by programmers. For example: there is no multiplication instruction. Computer composition: The properties that are embodied by the computer architecture. For example: how to implement multiplication instruction.

Second, the basic composition of the computer

1. Characteristics of von Neumann’s computer

1. The computer consists of arithmetic unit, memory, controller, input device and output device. 2. Instructions and data are stored in memory on an equal footing and can be accessed by address. 3. Instructions and data are expressed in binary numbers. 4. The instruction consists of an opcode and an address code. The opcode is used to indicate the nature of the operation, and the address code is used to indicate the location of the operand in the memory. 5. Instructions are stored in sequence in the storage. Usually, instructions are executed sequentially, and under certain conditions, the order of execution can be changed according to the results of the operation or according to the set conditions. 6. The machine takes the calculator as the center, and the data transmission between the input and output equipment and the memory is completed by the calculator.

Arithmetic unit:Arithmetic operation, logical operation;Storage:Store data and programs;Controller:Command the execution of the program, the order in which statements are executed;Input device:Converting information into a form that machines can recognize;Output device:Translate the results into familiar forms;

2. Computer hardware block diagram

2.1 Memory-centered computer hardware block diagram

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2.2 Modern computer hardware block diagram

The main memory can exchange information directly with the CPU; Auxiliary storage is also called auxiliary storage, also known as external storage; ALU: arithmetic logic unit, which performs arithmetic logic operations; CU: control unit used to interpret instructions in memory and to issue various operational commands to execute them;

3. How the computer works

3.1 Preparation before boarding the computer

(1) establish the mathematical model (2) determine the calculation method (3) work out the solution program

Instruction = opcode + address code

Example:

3.2 Computer problem-solving process

Basic composition of memory:

A Byte is defined as an 8-bit binary; MAR: Memory address register, reflecting the number of storage units; MDR: Memory data register, reflecting the storage word length; If MAR=4 bits, MDR=8 bits, then the number of memory cells is 2^4=16, memory word length is 8;

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Basic composition of arithmetic unit:

The arithmetic unit consists of at least 3 registers (ACC-accumulator, MQ- multiplicator, X- operand register) and an arithmetic logic unit (ALU);

Basic composition and operation process of arithmetic unit:

The basic composition of the controller:

The controller consists of program counter (PC), instruction register (IR) and control unit (CU).

  1. PC is used to store the address of the current instruction to be executed. There is a direct path between it and MAR of main memory, which can automatically add one to form the address of the next instruction.
  2. IR is used to store the current command, IR content to save MDR. Analysis instruction: OP(IR)– >CU.
  3. CU is used to analyze the operations that need to be completed by the current instruction and issues various sequences of microoperation commands that are used to control all controlled objects.

The process by which a host completes an instruction:

Main technical indicators of computer hardware

1. Machine word length

Machine word length refers to the number of bits of data that the CPU can process at a time, usually related to the number of register bits in the CPU. The longer the word length, the greater the range of representation and the higher the accuracy of the number. The machine’s word length also affects the speed of the machine. If the CPU word length is short, and to calculate more data, then need to go through two or more operations to complete, so is bound to affect the speed of the machine.

2. Computing speed

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3. Storage capacity

Storage capacity refers to the total number of bits of binary code. Storage capacity should include: main storage capacity and auxiliary storage capacity. MARThe number of bits reflects the number of storage units,MDRThe number of digits reflects the stored word length. Such as: MAR is 16 bits, and according to 2^16^ =65 536, there are 65 536 storage units in this storage body (64 K storage words, 1 K=1 024=2^10^). MDR is 32 bits, indicating that the storage capacity is 2^16^x32=2^21 =2 M bits (1 M=2^20^).

In modern computers, capacity is often described in terms of bytes. Since a byte is defined as an 8-bit binary code, the number of bytes reflects the capacity of main memory. For example, the above storage capacity of 2 M bits can also be expressed as 2^18^ bytes, denoted as 2^18^B or 256 KB(B is used to represent a byte).

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After class exercises:

What are computer systems, computer hardware and computer software? Computer system: a complex of computer hardware systems and software systems. Computer hardware: Electronic circuits and physical devices in a computer. Computer software: programs and related information required for the operation of a computer.

= =2. How to understand the hierarchy of computers?Computer hardware, system software and application software constitute three hierarchies of computer system. (1) The hardware system is the innermost layer, which is the foundation and core of the entire computer system. (2) The system software provides a basic operation interface for users besides the hardware. (3) The application software is in the outermost layer, providing users with the application system interface to solve specific problems. The layers outside the hardware system are commonly referred to as virtual machines. Each level is closely related to each other, the upper level is the extension of the lower level, the lower level is the foundation of the upper level, the division of each level is not absolute.

==3. How to understand computer composition and computer architecture? Computer architecture refers to the attributes of a computer system that are visible to programmers, such as the instruction system, data types, addressing technology composition, and I/O mechanism. Computer composition refers to how to realize the properties embodied in computer architecture, including hardware details that are transparent to programmers, such as the structure and function of various functional components that make up a computer system, and the method of interconnecting them.

==4. Explain the following concepts: == Host: Is the main part of computer hardware, composed of CPU and main memory MM.

CPU: The central processing unit (CPU), which is the core component of computer hardware and consists of an arithmetic unit and a controller.

1. The memory in a computer that holds running programs and data and is the primary working memory of the computer and can be accessed at random; It consists of a storage body, a variety of logic components and control circuits.

Storage unit: a unit of storage that can hold a machine word and has a specific storage address.

Memory element: A physical element that stores a bit of binary information. It is the smallest unit of storage in memory, also known as a memory element or memory element, and cannot be accessed individually.

Storage word: The logical unit of binary code stored in a storage unit.

Storage word length: The total number of bits of binary code stored in a storage unit.

Storage capacity: The total amount of binary code that can be stored in memory; (The main and auxiliary storage capacities are usually described separately.)

Machine word length: The number of bits of binary data that the CPU can process at one time, usually related to the number of register bits in the CPU.

Instruction word length: The total number of bits of binary code in machine instructions.

5. Explain the Chinese meanings of the following abbreviations: ==

CPU: The Central Processing Unit is the core component of computer hardware. It mainly consists of arithmetic Unit and controller.

PC: Program Counter, Program Counter, its function is to store the address of the current instruction to be executed, and can automatically count to form the next instruction address.

IR: Instruction Register, its function is to store the Instruction currently being executed.

CU: Control Unit, the core component of a controller, is used to generate sequence of microoperation commands.

ALU: Arithmetic Logic Unit, as the core component of an Arithmetic Unit, is used to perform Arithmetic and logical operations.

ACC: Accumulator, is a register in an arithmetic unit that can store both the operand before and the result of operation.

Multiplier: Multiplier-Quotient Register MQ: Multiplier-Quotient Register MQ: Multiplier-Quotient Register MQ: Multiplier-Quotient Register MQ: Multiplier-Quotient Register

X: This letter does not have an abbreviated meaning. It can be used as the name of any part. Here it represents the operand register, one of the operating registers in an arithmetic unit, where operands are stored.

MAR: Memory Address Register, used in main Memory to store the Address of the storage unit to be accessed.

MDR: Memory Data Register, used in main Memory to store Data read from or written to a storage location.

I/O: Input/Output equipment. It is used for converting and transmitting information inside and outside a computer.

MIPS: Million Instruction Per Second MIPS: Million Instruction Per Second

Instructions and data are stored in memory. How does a computer distinguish between them? = =

  1. Instructions and data are distinguished by different time periods, that is, instructions are taken out in the stage of taking instructions (or referring to microprograms), and data is taken out in the stage of executing instructions (or corresponding microprograms).

  2. According to address sources, the address of the storage unit provided by the PC is retrieved by the instruction, and the address of the storage unit provided by the instruction is retrieved by the operand.

From this article summed up “computer composition principle (2nd edition) Tang Shuofei” the first chapter of knowledge points. The pictures in this article are from “PPT of Liu Hongwei’s course of Harbin Institute of Technology”. Students who need Liu Hongwei’s PPT can pay attention to itCode farmers cloud libraryPublic reply “computer composition principle handout (Liu Hongwei)” can download the file.