1. The concept of stored programs (features of von Neumann computers)
(1) Computer (referring to hardware) should be composed of five basic components: arithmetic unit, memory, controller, input device and output device;
(2) Binary representation is used inside the computer to represent instructions and data;
(3) The preferred program and original The data is stored in the memory in advance, and then the computer is started to work. This is the basic meaning of the stored program;
2. Computer hardware composition
Host: Central Processing Unit (CPU) + main memory;
CPU = arithmetic unit + controller;
the main components of the computer
1.
Input device The task of the input device is to send the programs and original data compiled by people to the computer, and convert them into information that can be recognized and accepted inside the computer.
2.
Output device The task of the output device is to send the computer's processing results to the computer in the form of numbers, characters (Chinese characters), graphics, images, and sounds.
3. Memory
Memory is a component used to store programs and data.
4. The arithmetic unit The
arithmetic unit is a component that processes and calculates information.
5. Controller
The command center of the computer, according to people's pre-determined operating steps, controls the various parts of the computer to work in an orderly and automatic manner.
3. Bus structure
The bus is a group of public information transmission lines that can serve multiple components. It can send and receive information from each component in a time-sharing manner. (The simplest bus structure is a single bus structure);
Address Bus : consists of multiple signal lines in a single direction, used for the CPU to transmit address information to the main memory and peripherals;
Data Bus : It is composed of multiple signal lines in both directions. The CPU can read in data from the main memory or peripherals along these lines, and can also send data to the main memory or peripherals along these lines;
Control Bus : It transmits control Information, including control commands sent by the CPU and feedback signals returned by the main memory (or peripherals) to the CPU;
4. Multi-level structure of computer system
A modern computer system is a complex composed of hardware and software, which can be regarded as a multi-level structure divided by function;
level 0: hard-wired logic level
is the core of the computer, composed of logic circuits such as gates and flip-flops
. Level: Microprogram
level. The machine language at this level is the microinstruction set. Microprograms written with microinstructions are generally executed directly by the hardware.
Level 2: The traditional machine
level. The machine language at this level is the instruction set of the machine. Programs written by instructions can be interpreted by microprograms.
Level 3: Operating system machine level.
From the perspective of the basic functions of the operating system, on the one hand, it has to directly manage the software and hardware resources of traditional machines, on the other hand, it is traditional machine’s Extension
Level 4: Assembly language machine level
This level of machine language is assembly language, and the program that completes assembly language translation is called assembly language
Level 5: High-level language machine level
This level of machine language is a variety of high-level languages, usually Compile the program to complete the high-level language translation work
Level 6: Application language machine level
This level is specially designed to make the computer meet a certain purpose, so this level of language is a variety of problem-oriented application languages
5. The main technical indicators of the computer
1. Machine word length
The machine word length refers to the basic unit of the number involved in the operation, which is determined by the number of bits of the adder and the register.
2. Data path width
The data path width refers to the number of bits of information that the data bus can transmit in parallel at one time.
3. Main memory capacity
Main memory capacity refers to the total amount of information that can be stored in the main memory.
4. Computing speed
The calculation speed is related to many factors such as the main frequency of the machine, what kind of operation is performed, and the speed of the main memory itself.
(1) Throughput and corresponding time
Throughput refers to the number of requests processed by the system in a unit time;
response time includes the sum of CPU time and waiting time.
(2) Main frequency and CPU clock cycle
The main frequency of the CPU is also called the clock frequency, which represents the oscillation speed of the digital pulse signal in the CUP.
The reciprocal of the main frequency is the clock cycle of the CPU, which is the smallest time element in the CPU;
(3) CPI and IPC
CPI (Cycles per Instruction) refers to the number of clock cycles used for the execution of each instruction;
IPC (Instryction per Cycles) refers to The number of instructions executed per clock cycle;
IPC=1/CPI;
(4) CPU execution time
(5) MIPS and MFLOPS
MIPS (Million Instruction per Second) indicates how many millions of instructions are executed per second
MFLOPS (Million Floating-point Operations per Second) indicates how many millions of floating-point operations are performed per second.
MFLOPS is suitable for measuring the performance of a vector machine