[Java Basics] Computer basics

Computer = hardware + software 1. Hardware

1. Computer Core: CPU. CPU is the core of computer operation and control, it is used to receive computer instruction and run computation program.
2. Data is loaded into memory from the hard disk, and the CPU reads the data from memory. Memory Access data is fast, but after a power outage or exiting the program, the associated data in memory is lost.
3. Hard drive (mechanical + solid state): data can be stored permanently.

2. Software

Software is a collection of computer data and instructions organized in a specific order.

Software = instruction + data + documentation (software manuals)

1. System software (XP, Win7, Linux, Unix)
2. Application software (QQ, Fei Qiu, Lingbo)

3. Common ODS Commands

• Drive letter: Enter the specified drive letter. (d:\--into D-disk, CD for the same disk different folder conversion)
• dir : Lists the files and folders in the current directory
• MD: Creating a Directory
• Rd : Delete directory Note: Rd cannot delete non-empty folders, and can only be used to delete folders.
• CD directory path: Enter the specified directory. (CD D:\software, enter D from D:\ into D:\software Disk)
• CD.. : Back to the top level directory
• CD \ : Go back to the root directory
• echo "Hello java" >a.txt writing text to the specified file
• type a.txt display file Contents command
• del : Delete file Note: You cannot delete a folder, only files can be deleted.
• exit: Exit DOS command line
• CLS : Notifies the computer to empty the current command
• *: is a wildcard character.
• tab Command completion.
• The arrow keys are up and down to retrieve the last command you wrote.

[Java Basics] Computer basics