Computer Organization and functions
- Structure and functions of a computer
the computer is a high-speed calculation is for a computer. By a computer, may be implemented calculation, computer storage and other functions, also called computer (Computer) by a computer, may be implemented computing, storage and other functions.
Composition computer:
(1) hardware portions. The Von Neumann computer architecture proposed, a computer is divided into five parts: a controller, the arithmetic unit, memory, input devices, output devices:
(2) software components: assembly language, system software and application software, only software and hardware complement each other, it is a standard computer components
function (3) the various components:
hardware components:
arithmetic: arithmetic calculations also known as logical unit (ALU, arithmetic logic unit), responsible for the completion of the computer arithmetic and logical operations.
: controller CU (controller unit), the operator often collectively referred to as a central processing unit, i.e. the CPU, the core of the central computer, is responsible for overall coordination of the five members of the command, to ensure that computer to perform the specified requirements work.
Memory: a memory to store the main function of programs and various data, and high speed, automatically complete a program or data access while the computer.
Input device: an input device for the computer program and various raw data is called an input device.
Output Device: device is called an output device from the computer output of various types of data.
Software components:
assembly language (assembly language): a low-level language for cpu. It uses the mnemonic instead of binary language, easy to read and operate humanity.
System software (system software): or control hardware used to run developed computer software such as operating systems, compilers, database, etc. - Kernel function and the role of
the core of most operating systems, the memory management of the operating system, files, peripherals, and system resources components. System kernel is usually running processes, and to provide inter-process communication. Process management, memory management, network stack, file systems, drivers, security features. - By Series listed common Linux distributions and describe connections and differences between different releases of
ubuntu:
mainly for individual users
Benefits: Fixed release cycle and support period, novice-friendly, non-rich documents.
Disadvantages: Debian and has some compatibility issues; frequent updates may be the loss of some of the major users, Unity user interface has been criticized as more suitable for mobile devices.
Centos:
mainly used for enterprise-class server operating system
advantages: very stable and reliable; free to download and use
Cons: lack of the latest Linux technology; sometimes the project failed to fulfill its timely provision of security updates and new stable version.
openSUSE:
Pros: Comprehensive and intuitive configuration tool; a large library packages, excellent web site infrastructure and printed documentation
Cons: Microsoft's patent agreement seemed to Microsoft's intellectual property claims to Linux legalized; its resource heavy graphics and desktop settings tools are sometimes seen as "bloated and slow. -
Common open source license (GPL, LGPL, BSD, Apache, etc.) as well as open source protocol differences:
(1) can be freely copied:
you can copy the software to your computer, your customer's computer, or any place. Copies without any restrictions.
(2) can be freely distributed:
available for download on your website, copy the U disk to give as gifts, or print out the source code to throw out the window (environmental reasons, please do not do it)
(3) can be used to profit:
you can when the software in the distribution charge, but you must provide the GNU GPL license agreement for the software to your customers before charges, to let them know that they can get the free software, and the reasons for your charges from other channels.
(4) can be freely modified:
If you want to add or remove a function, no problem, if you want to use part of the code in other projects, no problem, the only requirement is that the use of this code must also project use the GPL. -
Linux description of philosophy, and according to their own understanding of its explanatory description:
(1) All documents are:
almost all the resources all abstract as a file, including hardware devices, and even communications interfaces such as:
physical terminal: / dev / console,
virtual terminal: / dev / tty # (# 1 to 6 ),
a serial terminal: / dev / ttyS #, pseudo-terminal:
/ dev / PTS / #,
all the resource files into the abstract, not only to facilitate the understanding and help manage
(2) from a number of procedures of the single function; a program do one thing and do a good job, a combination of a small program to complete complex tasks
(3) try to avoid user interaction with the target: easy to programmatically automate tasks
(4) to save the configuration information using a text file - Description linux directory structure and directory structure naming convention:
linux operating system in the main directory and directory contents by file system hierarchy standard (Filesystem Hierarchy Standard, FHS) definition.
/: Original starting point;
/ bin: basic commands available to all users of the program file;
/ sbin: system management utility for use;
/ the Boot: each static file boot loader must be used: kernel, initramfs (initrd), grub and the like;
/ dev: a storage device special file or files;
devices have two types: character devices (linear device), a block device (random equipment);
/ etc: the system's profile, only static;
/ Home: normal centralized location of the home directory; for each ordinary general user's home directory and subdirectory of the default user name the same name under this directory, / home / uSERNAME;
/ root: administrator's home directory; optional;
/ lib: system or application startup (/ bin, / sbin, etc.) on the root file system provides shared libraries, as well as the kernel kernel modules
libc.so. : a C dynamic link library;
LD : run-time linker / loader;
modules: directory for storing kernel modules;
/ the lib64: 64-bit system-specific storage path 64 shared library;
/ Media: portable device mount point, cdrom, floppy, etc.;
/ mnt: other temporary mount point of the file system;
/ opt: the installation position of the additional application program; optional path;
/ SRV: The current data service provided by the host;
/ tmp: provide for programs that will produce a temporary file in the directory for storing temporary files; for the user to perform a write operation; special privileges;
/ usr: usr Hierarchy, globally shared, read-only data path;
bin, sbin
lib, lib64
the include: C header files;
report this content share: storage location and command manual pages and other documentation that comes with the unique architecture of the file
local: another level directory;
X11R6: X-Window program installation position of
src: program source file storage location
/ usr / local: local hierarchy, allows system administrators to install local applications; also commonly used to install third-party programs;
/ var: / var Hierarchy, data storage directory changes often occur;
/ proc: memory-based virtual file system for storing the kernel and process information about it; they are mostly kernel parameters,
/ SYS: sysfs virtual file system provides a way to access the kernel data proc more than ideal; their main role is to manage to provide a unified model of the Linux device interface;
file name using the rule:
strictly case sensitive characters: file1, file1, fILE1
head It is the file, in the same path, two files with the same name can not;
supports any character other than /;
no longer than 255 characters;