1. What is the programming language?
Language is the medium of communication of things A and B of things. Chinese, English and Japanese language is the medium of communication between people. The programming language is the medium of communication between man and computer.
2. What is programming?
As English as a sentence composed of words and grammar. The syntax and programming is to write a bunch of characters to work in the computer file, the result is a pile of documents, which is the program.
3. Why programming?
The purpose computer as their slaves, slavery is a computer programming, computer help to make their own work, to replace manpower, save yourself time and effort
Five computers were part 4. What is the role?
The computer has a composition of five controllers, arithmetic unit, memory, input devices and output devices
Controller: the equivalent of the operation of the brain that controls the body's organs
Operator: arithmetic and logic operations implemented
Memory: a computer storage system, the equivalent of human memory organization. There main memory and external memory points.
| RAM | External memory | |
|---|---|---|
| Shortcoming | It is smaller than the external memory and because the memory capacity for storing data based on the dot, the power data immediately disappear | Slower than the memory access speed |
| advantage | Faster than the external memory access speed | Than the memory capacity can be stored permanently |
input device
Computer input information (programs, data, voice, text, graphics, images, etc.) equipment.
Common input devices are: keyboard, mouse, graphics scanners, touch screens, bar code input, a light pen and so on. External memory (U disk, etc.) is also an input device
Output Device
Computer output device information.
Common output devices include: monitor, printer and plotter. The memory is also an external output device.
Note: Since the external memory that is an input device, is also an output device, and therefore is also called external memory IO device, where I is the Input (Input); O as the Output (output).
The mechanical hard drive works?
Mechanical hard drive consists of a mechanical arm, track and sector composition of
the contents of references to nickchen teacher blog
- 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.
Average delay time: 7200/60 = 120 (r / s)
1/120 = 0.0083 (s / r) = 8.3 (ms / r)
8.3 / 2 = 4.15 (ms / r)
Average delay time: 7200/60 = 120 (r / s)
1/120 = 0.0083 (s / r) = 8.3 (ms / r)
8.3 / 2 = 4.15 (ms / r)
It can be derived from the above description:
Find data = average seek time + average delay time data to find a time = average seek time + average delay time
6. qq start
- Double-click the Windows desktop QQ icon (shortcut qq.exe corresponding path)
- Double-click the icon that is sent to the operating system instructions that tell the hard disk address corresponding operating system software QQ, and let the operating system starts this path
- Operating system receives an instruction to send instructions to the memory control CPU
- After accepting an instruction memory to send instructions to the hard disk, the hard disk memory to the software code read QQ, QQ start