• The composition of a computera complete set of computer systems are divided into: hardware, operating system, software. hardware system: Arithmetic, controller and memory, input device, output device. 1. Arithmetic: Responsible for arithmetic and logic operations, together with the controller to form the CPU. 2. Controller: Send and receive Instructions3. Memory: Store program code and data4. Input devices: such as keyboard and mouse5. Output device: For example, Monitor. software system: A program developed for the completion of a particular work, divided into system software and applications. system software: Operating system, control and coordination of computer and external devices, supporting the development and operation of application software systems. application software: such as QQ and so on. Two • The role of programming languages, as well as the relationship to the operating system and hardware:we use programming languages to develop specific applications to accomplish a particular goal, and this application is run on the operating system we use, by invoking the appropriate interface of the operating system to complete the data interaction with the underlying specific hardware. three · Cpu-> Memory-DiskCPU: The arithmetic and controller are called CPU (central processing Unit), its function is mainly to explain the computer instruction and processing computer software data. Memory: The program runs in memory, and the memory temporarily stores the CPU's operational data and the data exchanged with external memory such as the hard disk, and loses power. Disk: External data memory, which stores large amounts of data, is non-volatile. Four · CPU and registerCPU and register: Register is a part of the CPU, is used for high-speed limited storage of data, a class of parts, can be used to hold instructions, data and addresses, access speed than access to memory much faster, the CPU by providing instruction set to complete the register and memory data interaction. The program Status Word register is a very important part of the register, and its contents contain various control bits, both system calls and IO operations are related to it. It is possible to switch modes (user state and kernel state) through it. Five • Kernel state and user stateKernel State: Privileged mode, the CPU can access all the memory data, including peripheral devices, the CPU can also be a program switch. User state: Non-privileged mode, the code executed receives hardware restrictions, does not allow access to peripherals, and is deprived of the ability to occupy the CPU. Our software is running in the user state, but sometimes there is the need to operate the hardware, so you have to switch to the kernel state, due to the protection of the instructions in the kernel state, can only jump to the location to load instructions, called System call, the system call, Resets the CPU to the user state and returns the execution result. This writing is good, recommended http://www.cnblogs.com/zemliu/p/3695503.html. Six • Memory seriesL1 Cache: integrated in the CPU, for the CPU in processing data in the process of the temporary preservation of data. The more information the cache stores, the fewer data exchanges between the CPU and memory, and the higher the CPU execution efficiency. But because of the integration with the CPU, the capacity cannot be too large. L2 Cache: The temporary memory between CPU and memory, which can be understood as a buffer of primary cache, is used to store the data that the CPU needs to use but cannot be stored in and in memory, and the capacity is smaller than the memory, but the exchange speed is fast. how the Cache works: When the CPU is going to read a data, it is first looked up from the cache, read and sent to the CPU if it is found, and if it is not found, it is read from memory and sent to the CPU at a relatively slow speed, and the data block where the data residesin the cache, you can make the whole chunk of data read later from the cache, do not have to call memory, it is such a reading mechanism to make the CPU read cache hit rate is very high (most CPUs up to about 90%), that is, the next time the CPU to read 90% of the data in the cache, Only about 10% need to be read from memory. This greatly saves the CPU time to read the memory directly, and also allows the CPU to read the data basically without waiting. In general, the CPU reads the data in the order that it caches the memory first. (Baidu Encyclopedia)Memory Ram (Random Access memory): power-down, lost storage unit, the main storage system. e2prom: Electrically erasable rom, non-volatile storage unit. Flash (Flash): Storage data does not lose power loss, and access is very fast, small capacity, is a digital camera film, MP3 storage disk, but also for solid-state drives. CMOS and Biso batteries: the computer field refers to the storage of basic computer startup information (such as date, startup settings, etc.) of the chip, used to save the BIOS hardware configuration and user settings for certain parameters, by a button battery drive power supply, ensure that the data is not lost, because the program consumes little, so it can run for a long time. Seven · disk structure and virtual memory disk structure: Magnetic coiled around a central spindle rotation, the disk has a track, the track is a circle of concentric circles, by the robotic arm with the head for data reading. Average seek time: the average time that the head moves to the track where the data resides when the computer issues an address command. Average delay time: Because the data is stored in different sectors, the head to the corresponding track, but also to wait for the head to move to the sector where the data, this period is the average delay time. Virtual Memory: The large number of programs is larger than the size of the computer memory, and the computer can execute such a program is due to the use of virtual memory mechanism, by putting a program that does not need to be executed on the disk area, and this area becomes so-called virtual memory, in Linux is swap, Resolve insufficient memory capacity. MMU Management Unit: Memory management unit for managing virtual memory,responsible for quickly mapping memory addresses. Context switch: Fast switching between programs, together with the MMU, significantly improves the performance of computer system operation and processing. Eight • Tape data reads and writes much lower than hard drives, but at the same price, it has more storage capacity and is easy to transfer, often used as a data backup in large databases. Nine · Controller and device driver controller: The controller is responsible for controlling the relative equipment, the purpose is to shield the operating system from the specific underlying hardware directly complex and specific control device driver:device drivers are between operating systems and IO devicesof Adhesives. The driver is responsible for transferring the request of the operating system into a specificcommands that the controller can understand. 10 • Bus with North Bridge and South Bridge bus:bus is an internal structure, it is CPU, memory, IO devicea public channel that transmits information,each part is connected by bus,Bei QiaoNorth Bridge Chip is the motherboard on the latest chip from the CPU, which is mainly considering the bridge between the chip and the most close communication between the processor, is the PCI bridges, connect high-speed signal. South Bridge : Far from the CPU socket, the number of connected IO bus, responsible for some peripheral interface control, ISA Bridge, connect low-speed signal. 11 · BIOS and operating system start-up processBIOS (Basic Input Output System): A set of program small operating systems that are cured to a ROM chip on the motherboard of a computer, the main function is to provide the most direct hardware settings and control for the computer. Operating system startup process: Power on, run the BIOS, System self-test, read the CMOS parameters, start the corresponding device-read sector content, read-in bootloader boot loader module, start the operating system, check the driver for each device 12 · Application initiation Process Application initiation process: The operating system monitors the input device (mouse or keyboard) operation request, if the corresponding operation, find the need to execute the file on the hard disk location, the need to execute the program loaded into memory, the application began to execute.
The path to Python-Computer fundamentals
