Brother Bird's Linux private vegetable notes (one)

Computer overview

1. The computer receives the user input instruction data, after the CPU data and the logical unit computation processing, produces or stores the useful information--->i/o device +cpu+ processing information = computer.

2. Computer Five main unit: I/O Unit internal unit of the CPU inner control cell CPU internal arithmetic logic unit

3.CPU contains instruction set->risc, simplified instruction set, instruction execution time short performance good->arm series and so on.

->cisc, complex instruction set, command Processing task content Rich->x86 series and so on.

4. The motherboard connects all the devices together, the important component is the chipset->intel Series CPU Board chipset-and two bridge control components of the communication----North bridges are responsible for connecting the faster CPU, memory and graphics components. The –> South Bridge is responsible for connecting peripherals with slower speeds.

5.AMD series CPUs integrate memory control components into the CPU in order to accelerate CPU-to-memory communication. This is different from Intel.

6. Motherboard Components CPU Memory disk device (IDE/SATA) bus chipset Graphics Interface (pci-express) adapter card

7.cpu FSB refers to the CPU and external components for data transmission or operation of the speed, octave is the CPU used to speed up the performance of a multiple, the two are multiplied by the CPU frequency

8.cpu overclocking refers to the CPU FSB or octave through the motherboard's setting function change to a higher frequency, the multiplier is set up at the factory, so it is usually changed the CPU FSB.

9. North Bridge's bus is called the system bus, is the main channel of memory transmission so fast. The South Bridge bus is an I/O bus for contacting peripherals.

10. North Bridge supported frequency we call the front-end bus speed (FSB), the number of bits per transmission is the bus width, the maximum amount of data can be transmitted per second->fsb* bus width.

11.cpu The amount of data that can be processed each time is called the size of the word group, and the 32/64-bit setting of the computer comes from the CPU-resolved word group size.

The primary component of 12.pc memory is dynamic random access memory, which loses data->sdram synchronous dynamic random access memory->ddr SDRAM (double data rate)

The 13.SRAM static random ACCDSS memory can be integrated within the CPU as a cache (L2 cache).

14.BIOS (Basic Input output system) is a set of startup read programs written in the motherboard ROM, now with the development of the computer, the BIOS needs to be updated so now the BIOS is written in flash memory or EEPROM.

15. Each component parameter on the motherboard is written in a CMOS chip and the data is read and updated through the BIOS.

16. Graphics Card (VGA graphics array), North Bridge Connection, with the upgrade of the component, the bandwidth of the data transmission is larger the current specification is pci-express.

17. Hard disk is composed of many platters, mechanical arm, head, spindle motor, data written on the magnetic disk, read and write through the mechanical arm of the head (head) to complete, the spindle motor to rotate the disc, the mechanical arm stretching the head on the disk surface for reading and writing operations.

18. There are a plurality of concentric circles on the surface of the drawing, and from the center of the radial way to split the smallest storage unit is the sector, each sector size is 512bytes, the sector consists of a circle is a track, multi-disc, all the tracks on the disc can form a cylinder surface, A cylinder is the smallest unit of a split disk. head*cylinder*sector*512bytes

19. The transmission interface (IDE SATA SCSI) IDE interface of the hard disk and the host can be connected to two IDE devices, You need to adjust the skip pin settings master-slave disk. SATA interface Fast and easy to install heat dissipation device, SCSI interface hard disk on the control of a processor is fast and does not consume CPU resources.

20. The chipset on the motherboard is responsible for the communication of all devices in the computer, the CPU identifies the device through an I/O address, and each device informs the CPU of the status of the device's work through the IRQ interrupt channel for the CPU to allocate tasks.

21.CMOS records a variety of important parameters on the motherboard, such as system time,cpu frequency and voltage, the I/O address of various devices and IRQ interrupt, etc., record these need electricity so the motherboard has battery. The BIOS is a program that writes to a flash-alive EEPROM, loads the CMOS parameters during power-on execution, attempts to invoke the boot program in the storage device, and further enters the operating system.

22. The operating system is the management and control of computer system hardware and software resources, the effective use of computer software and hardware resources to provide users with a powerful, stable working environment, so as to play an interface between the computer and the user a set of programs.

23.os provides a program interface and user interface, the program interface is the programmer through the system call Operation kernel control hardware operation, written application is the operating system provides the development interface, all can only run on the operating system. The user interface is used by the user to interact with the computer, through the GUI and CLI, Where CLI is a command-line interface, the shell command interpreter needs to be configured, and the shell is an application that runs on the OS

Rules and installation of Linux

The 1.linux OS is a multi-user multitasking operating system and is a UNIX-like operating system. Linux has a kernel version and a release version.

2.linux before the History of Unix, Bell Labs Mulitics system->ken Thompson's UNICs (assembler)->ritchie writes out the Unix kernel (C language).->bill Joy writes out the UNIX branch bsd--is only suitable for its own computer hardware, and no other schema can run (such as no longer running on x86)->minix System x86 architecture Unix-like system->torvalds write out the Linux kernel.

The 3.POSIX (Portable Operating system Interface) Portable operating system interface is used to standardize the interface between the kernel and the application.

4.GNU with Gpl,gnu project and the PSF Free Software Foundation, GPL general Public License. Linux is the GNU project so Open source, and the current Redhat and other companies selling Linux distributions are not systems but selling services.

5. In order to standardize the distribution of Linux distributions, there are FHS and LSB specifications, so the major Linux distributions differ only by developer's development of management tools and custom software.

6.linux under all documents, access to the device is also stored in the form of files, the purpose of a single small program, composed of small programs to complete complex tasks, configuration files saved as txt text.

7. Hardware file name in Linux, IDE hard disk/dev/hd[a-d], SATA or SCSI HDD/dev/sd[a-p]. The first sector of the disk holds two important information, the primary boot partition Mbr[master boot record],446bytes , the partition table records the hard disk partition status is 64bytes. The system opens the opportunity to read loading the MBR, the partition table is only 64bytes, so it can only accommodate 4 partitions, called primary partitions or extended partitions. The purpose of an expanded partition is to use additional sectors to record partition information, and partitions under the extended partition are called logical partitions. An extended partition can have .

8.MBR Install the boot loader where boot loader is installed, boot loader is the software that reads the kernel files to execute. Features that provide a selection menu to load the kernel file to transfer to other loader.

9. The boot process, the BIOS reads the parameters on the CMOS, reads the boot loader loaded in the MBR and enters the operating system. The bootloader can be installed in the MBR and boot sectors.

10. Each partition has its own boot sector, the bootable kernel file is placed on each partition, loader can only recognize the kernel files of its own partition and other loader.loader may give management to another management program.

11.window and Linux disk partitions. Under Windows we can divide disks by disk characters. Assume that only C can be used as a drive letter under Windows. How do we divide the area?

We can build a folder in the C drive and then load the other partitions into this folder, and when we visit the folder we built in C, we actually access the partition.

Linux is only/can be a drive letter, and other partitions are mounted under/under this condition under Windows. This is where we open Linux. The file system sees no partitions and sees only a variety of folders.

12.VM installation centos5.5 with TXT installation GUI installation, first installation recommended full installation, Partition division,/boot,/, home, swap. With graphical interface installation, SELinux is set to mandatory, disable firewall.

13. Forget the root password, restart the system when the system is loaded press any key to enter the editable interface, select the kernel press the E key to enter the editing state, after adding a single after pressing the B key, into one-user mode, using the passwd command to change the root password can be.

14. Execute commands in command-line mode. command [options] ... arguements. Simple commands date cal BC.

15. Important Hotkey Ctrl+c,ctrl+d,tab.ctrl+c is used to stop execution of the command. Ctrl+d represents the end of the keyboard input, it can also replace the input of exit, Tab for command completion or file name completion.

16.linux several handy shortcut keys CTRL + A CTRL+E jumps from the cursor position to the beginning or end. Ctrl+u ctrl+k

From the cursor position, delete to the beginning and end. ESC. Quickly reference the last parameter used.

The man page view, enter the man pages using the Space key paging, press the Q key to leave, support keyword search,/key.

18. Proper shutdown and restart command, root user performs shutdown halt reboot Poweroff reuse shutdown shutdown–r now shutdown–h now stop service restart shutdown, reboot–f Poweroff- F Restart shutdown now

19. Switch execution level INIT/ETC/INIT.D OR/ETC/RC.D/INIT.D where Init is divided into 7 levels, init 0 shutdown init 6 restart init 3 CLI mode init 5 GUI mode runlevel view execution level

Brother Bird's Linux private vegetable notes (one)