table of Contents
1. Programming
What is the programming language:
Media people and computers communicate.
What is the program:
Human beings in order to achieve some purpose, using the programming language to write a series of documents.
Why Programming:
By programming in some work, let the computer replace the human to do some work.
2. Composition of the computer
2.1 CPU
Controller
Command system of the computer.
Operator
Arithmetic operation is a computer system, arithmetic and logic operations.
2.2 Memory
Main memory (RAM): hardware within a computer temporarily stores data.
Advantages (compared to the external memory): access speed.
Disadvantages (compared to external memory): small capacity, power data disappear.
External memory (hard disk): computer hardware within the permanent storage of data.
Advantage (compared to memory): capacity, it can be stored permanently.
Disadvantage (more in memory): slow access speed.
2.3 IO devices
Input Input device: computer input device information.
Common input devices are: keyboard, mouse, scanner, touch screen, U disk and so on.
Output Output Device: computer output device information.
Common output devices include: a display, a printer and a U-like.
2.4 Supplementary
2.4.1 CPU-related
- Multicore CPU: a plurality of CPU, the computer can process different tasks at the same time.
- 32-bit / 64-bit: indicates the CPU to transmit data, respectively, are transmitted according to 32/64-bit binary data,
2.4.2 mechanical hard disk works
- Robot: mechanical hard disk data read by the robot arm, the robot arm is the head end.
- Tracks: a track circle is a magnetic surface of a mechanical hard disk, for storing data track.
- Sector: The sector is generally the smallest unit of 512KB (since the disk size increasing, some manufacturers have set for each sector size is 4096 bytes). In order to reduce IO operations, also a plurality of mechanical hard disk adjacent sectors together, form a block, then the block is what we see in the Windows system C, D partition.
- Average seek time: Because the data stored on the track, so the mechanical arm needed to read the data must first find the track. Limited by the limitations of industry standards, the current robotic arm to find the track time is 5ms , the average seek time is called.
- The average delay time: after the mechanical arm seek, need to find data. Because location data is uncertain, and the current mechanical hard to find data scans the hard disk from the head to the tail. In the hard disk 7200r / min for example, if by chance the data found in the hard disk head, time is about 0ms; If the data is found in the hard disk tail time is about 8.3ms, so we use a robot as the average time 4.15ms found in the track time data, this time is referred to an average delay time.
2.4.3 Bus
All hardware connected to a computer.
2.4.4 memory-related
Memory ROM: read-only memory ROM (not write) was completed at the factory programmed, and can no longer be modified. It is generally stored BIOS (Basic input output system) program, which is generally used to start the computer, for controlling or processing the underlying device.
CMOS memory: CMOS memory of a computer built-in battery-powered drive, which is generally held to update the current time and date, that is to say, even if the computer is not charged, will continuously update time; it also can store a boot disk path .
3. Operating Systems
3.1 What is a file
The concept of a virtual operating system, used to store information.
3.2 What is the application procedure
Paper prepared by methods that can achieve some kind of file or more specific functions.
3.3 What is the operating system
Computer hardware and the operating system is located between the application software, which is a control program coordinated management of computer resources and software resources.
3.6 operating system role
Can not easily and directly interact with the computer hardware, operating system, the hardware complexity of the operation, a package into a simple interface, for people to use. People only need to interact with the operating system, the operating system performs this operation to complete all required steps and hardware interaction.
Start 3.7 operating system and applications
- Operating system startup (boot):
- 1. Power
- 2. The operating system code is read from the hard disk into memory (BIOS program)
- 3.CPU run the operating system code (CMOS memory), the operating system takes over operations after hardware to run a successful work
- 4. Power Success
- Start the application (to QQ, for example):
- Double-QQ (operation to send instructions to the CPU)
- CPU sends commands to the memory
- Send commands to the hard disk memory, read data qq
- qq data into memory
- Start qq