1, keyboard
Keyboard is a commonly used input device, which consists of a set of switch matrices, including numeric keys, alphabetic keys, symbol keys, function keys and control keys. Every key has a unique code in the computer. When the key is pressed, the keyboard interface sends the binary code of the key to the host and displays the key characters on the display.
When a large number of characters are input quickly, and it is too late for the host to process them, the codes of these characters are first sent to the keyboard buffer of the memory, and then taken out from the buffer for analysis and processing. The keyboard interface circuit mostly uses single chip microcomputer to control the work of the whole keyboard, such as keyboard self-inspection, keyboard scanning, key code generation and transmission, communication with the upper computer and so on.
Step 2: Rats
Mouse is a hand-held screen coordinate positioning device, and it is an input device suitable for menu operation software and graphics processing environment, especially in the popular Windows graphics operating system environment. There are two kinds of commonly used mice, one is mechanical and the other is photoelectric.
Several common input methods:
1, punch in
Punched cards are combined representation data punched at predetermined positions. The most commonly used card is 82.6 mm wide, 187.3 mm long and 1.78 mm thick. It has 80 vertical columns, and each column has 12 perforation positions. Type 1, 2 or 3 holes in a column to represent a character. Each card can record a transaction, an account or a record.
2. Perforated belt input
Punched paper tape is made of paper, plastic or metal, and some round holes are punched on the paper tape to record data. According to the width of the belt, it is divided into 8 unit belts, 7 unit belts and 5 unit belts.
The combination of holes in a row of holes in the transverse direction of the belt represents a 5-8-bit character code. The input of punched tape is offline. First, the data is recorded on the punched tape by the punch, and then the data is sent to the processing system by the punched tape reader.
3. Tape input
Magnetic tape uses the magnetization direction of the surface magnetic layer to record information. It has the advantages of high density, good economy, easy to erase and reuse, and is the most used input and output carrier in electronic data processing systems.
4. Disk input
A magnetic disk is a non-magnetic disk that records data based on a magnetic layer on its surface. It is installed on the vertical shaft, and the rotating speed is 2400 ~ 3600 rpm. Disk is one of the most important data carriers.