Computer booting is a mysterious process. We just press the power button, and see the progress bar or line-by-line output on the screen until we reach the login interface. However, booting the computer is an extremely fragile process. The login interface we hoped for may not appear, but a command line or error message. Understanding the computer boot process helps us fix problems that may occur when booting.
Initial stage
When we turn on the computer's power, the computer will automatically read the programs stored in the BIOS (Basic Input/Output System) of the motherboard. This program usually knows some hardware (hard disk, network interface, keyboard, serial port, parallel port) directly connected to the motherboard. Most of the BIOS now allows you to choose one of floppy disks, CDs, or hard disks to start the computer.
In the next step, the computer will read the initial 512 bytes from the storage device you selected (for example, the 512 bytes when the CD is opened, if we boot from the CD). This 512 bytes is called the master boot record (MBR). MBR will tell the computer to load the boot loader from a certain partition of the device. Boot loader stores operating system (OS) related information, such as the name of the operating system, the location of the operating system kernel (kernel), and so on. Commonly used boot loader are GRUB and LILO.
Subsequently, the boot loader will help us load the kernel (kernel). The kernel is actually a program used to operate the computer. It is the kernel of the computer operating system. Its main task is to manage the hardware resources of the computer and act as an interface between software and hardware. Any operation on the operating system must be communicated to the hardware through the kernel. Windows and Linux each have their own kernels. The operating system in the narrow sense refers to the kernel, and the operating system in the broad sense includes the kernel and various applications on the kernel.
(Linus Torvalds is not so much the father of Linux as the father of the Linux kernel. He is still responsible for the development and maintenance of the Linux kernel. As for Ubuntu and Red Hat, they are all based on the same kernel and include different applications and The interface constitutes a more complete version of the operating system.)
In fact, we can install the boot loader in multiple partitions, each boot loader corresponds to a different operating system, and when reading the MBR, select the boot loader we want to start. This is the principle of multiple operating systems.
Summary: BIOS -> MBR -> Boot Loader -> Kernel
Kernel
If we load the Linux kernel, the Linux kernel starts to work. The kernel will first reserve the memory space needed for its own operation, and then detect the computer hardware through the driver. In this way, the operating system can know what hardware it has available. Subsequently, the kernel will start an init process. It is process No. 1 in Linux system (Linux system does not have process No. 0). At this point, the kernel has completed the work in the computer startup phase and handed over to init for management.
Summary: Kernel -> init process
init process
(According to the boot loader option, Linux can enter single user mode at this time. In this mode, the initial script has not yet started execution, we can detect and repair possible errors in the computer)
Subsequently, init will run a series of startup scripts, which are common shell scripts in Linux. These scripts perform the following functions:
Set computer name, time zone, detect file system, mount hard disk, clear temporary files, set network...
When these initial scripts, the operating system is fully prepared, but no one can log in yet. init will give a login dialog box, or a graphical login interface.
Enter the username (for example, vamei) and password, DONE!
In the subsequent process, you will operate the computer as user vamei. In addition, according to your settings when you create a user, Linux will also assign you to a certain group (group), such as the stupid group or the vamei group.
So you will be the user vamei and a member of the vamei group. (Note that the group vamei and the user vamei just have the same name, just like you can be called Dell, and you are the boss of Dell at the same time. You can also be the user vamei and a member of the stupid group at the same time)
to sum up
BIOS -> MBR -> Boot Loader -> Kernel -> init process -> login
user group.
REMOTE CONTROL SOCKET
Important Safeguards
When using any electrical appliance, in order to reduce the risk of fire, electric shock and/or injury to persons, basic safety precautions should always be follow8d. including:
• The appliance is for household and indoor use only.
• Before plugging in. check that the voitage on the rating label is the same as the mains supply.
• To protect against electric shock, do not immerse any part of the product in water or other liquid.
• This socket is intended for use by competent adults only and children should be supervised at all times.
• Do not use the socket for other than its intended use.
• This socket can be used by children aged from 8 years arxl above and persons with reduced physical, sensory or mental capabilities or lack of experience and knowledge if they have been given supervision or instruction concerning use of the appliance in a safe way and understand the hazards involved. Children shall not p<ay with the appliance Cleaning and user maintenance shall M be made by children without supervision.
• Children of less than 3 years should be kept away unless continuously supervised.
Children from 3 years and less than 8 years shall only switch on/off the appliance provided that it has been placed or installed in its intended normal operating position and they have been supervision or instruction concerning use of the appliance in a safe way and understand the hazards involved. Children aged from 3 years and less than 8 years shall not plug in. regulate and clean the appliance or perform user maintenance.
• Don't use this socket in the immediate surroundings of a bath, a shower or a swimming pool.
• In case of malfunction, do not try to repair the socket yourself, it may result in a fire hazard or electric shock
Do Not Exceed Maximum a680W
Place the LR44 batteries provided into the compartment in the back of the Remote Control, please insert as sho*/m in the back of the compartment to ensure the polarity is correct.
Programming Instructions
• Plug the Remoce Socket$($)lnto the wall socket(s) and switch on the mams supply, the red LED will flash every second.
• If the LED is not flashing press & hold the manual ON/OFF button for 5 seconds until it Hashes
•Press any ON switch on the Remote Control for approximately 2 seconds and the Remote Socket(s) learn the code. The LED will stop flashing top confirm the codehas been accepted.
• Any number of Remote Sockets can be programmed to one Remote Control ON button to create multiple switching.
• To programme o<her Remote Sockets on different Remote Control ON buttons repeat the prevous steps
• If the mains supply is turned off the Remote Sockets v/ill lose their code and it wil be necessary to re-pcogramme.
Operation:
• Plug your appliance(s) into the Remote Socket(s)
• Press the programmed ON or OFF button on the Remote Control to control the Remote Socket.
♦ The Remote Sockets can also be operated manually using its ON/OFF Button Trouble shooting
If a Remote Socket does not react to the Remote Control please check the followng:
♦ Low battery in tbo Remote Control
• Distance too large between the remote control and the recerver (ensure the range distance is no more than 20 clear Metres) and free from obstacle that may reduce the distance.
• If programming has not been successful, tum the power off and back on then follow the programming steps above.
How to decode
• Press the manual ONX)FF button for 5 seconds until the red LED flashes once per
second to confirm de-coding is successful
♦ Press the ALL OFF switch on the Remote Control for more than 3 seconds, the LED
flashes once per second to confirm (decoding successful.
Voltage: 240V-/50HZ
Max power rating: 3680W max.
Remote frequency:
Remote range:
Battery Type:
433.92MHz
230 Metres
Button Cell 2x1.5V LR44 =
Please check with your local waste management service authority regarding regulations for the safe disposal of the batteries. The batteries should never be placed G municipal waste.
Use a battery d^posal facility if available
M
For eioctncal products sold within the European Community. At the end of the electrical products useful life, it should not be disposed of wth household waste. Please recycle faaMies exist. Check with your Local Authonty or retailer for recycling advice.
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Remote Control Plug Socket,Remote Controlled Mains Outlet,Remote Control Plug Adapters,Remote Control Sockets,Remote & Smart Controlled Sockets,Electric Sockets Plus Remote Control
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