"Brother Bird's Linux private cuisine-Basic Study (third edition)" (a)

Before the book over, but for a long time not to forget the same =, so decided to take it back again, by the way to share and record. The book is divided into five parts, 26 chapters, about 780 pages, more content, may be updated longer.

The first part Linux rules and installation

Chapter NO. 0 Introduction to Computer science

1. Computer: A good tool to assist the human brain

This section is the popularization of computer knowledge, or a brief summary.

First of all, the computer hardware of the five major units . The input unit, Output Unit, control unit (coordinate the work between each component and each unit), Arithmetic logic unit (responsible for program operation and logic judgment), and memory, respectively.

Then we talk about the type of CPU .

1) compact instruction set (reduced institution set Computing,risc), mainly with the company's SPARC series, IBM's Power Architecture series and arm series.

2) Complex instruction set (Complex institution set Computing,cisc), mainly with AMD, Intel, via and other x86 architecture of the CPU, their main difference is the micro-instruction set is different. Because the first Intel developed a CPU codenamed 8086, the PC is often referred to as the x86 architecture computer. The 64-bit PC CPU is also collectively referred to as the x86 64 architecture.

Next talk about the interface device . The most important interface device is the motherboard, and the most important component on the motherboard is the motherboard chipset. In addition, there are storage devices, display devices, network equipment and so on.

There are also operational processes .

The computer classification is also discussed. It is divided into supercomputers, mainframe computers, mini-machines, workstations and microcomputers.

Finally, we discuss the computing units (size, speed, etc.) commonly used in computers. 0/1 of the units are called Bit,1byte=8bit, and then k,m,g,t,p respectively. The file size is used in binary mode, and the speed unit is used in decimal. The GPU's operating speed is often used in MHz or ghz,hz, which is actually one of the seconds. The unit used in the network is Mbit/s. The average hard drive manufacturer uses a decimal unit.

2. PC Architecture and Interface devices

What the general consumer often says about computers is x86 's personal computer architecture. Two major x86 developers are the Intel and Amd,intel architecture chipsets are usually divided into two bridges to control the communication of each component: the North Bridge is responsible for connecting the CPU, memory and graphics components, and the South Bridge is responsible for connecting the slower peripheral interfaces. The AMD architecture differs from Intel in that memory is directly communicating with the CPU without passing through the North Bridge. The following is an example of the Intel chipset architecture and gigabyte motherboard.

       first spoke CPU . The so-called multicore CPU is the embedding of more than two compute cores in a single CPU package. Most different CPU models have different foot positions and can be paired with different motherboard chipsets. Frequency is the number of times the CPU can work per second, but the frequency can only be used to compare the speed of the same CPU at this time. FSB is the speed at which the CPU and external components transmit/operate, and the multiplier is a multiple of the CPU used to speed up the performance, and multiplying is the frequency of the CPU. The so-called overclocking refers to the CPU multiplier or FSB through the motherboard's setting function to change to a higher frequency of a way, usually overclocking is FSB. The bus of the North Bridge is called the system bus, and the bus of the South Bridge is called the input/output (I/O) bus. The frequency supported by the North Bridge is called the front-end bus speed (FSB), and the number of bits per transmission is called the bus width. The bus bandwidth is the "FSBX bus width", which is the maximum amount of data that can be transmitted per second. The common bus width is 32/64 bits. The amount of data that the CPU can process each time is called the size of the word group, and the CPU is designed with 32-bit and 64-bit, which is the 32-bit computer and 64-bit computer. 32-bit CPUs can only support up to 4G of memory. Note that the size of the word group and the bus width can be different.

And then talked about the memory . The main component of the memory of a personal computer is dynamic random access memory (Memory,dram), which can only be recorded and used when power is turned on, and the data disappears after power loss, and becomes volatile memory. DRAM can also be divided into SDRAM and DDR SDRAM two, most of which use DDR now because of its better transmission frequency. For a two-channel design, the two memory is remitted together, but two of the same memory must be inserted in the same color slot. The second-tier cache (L2 cache) is integrated into the CPU and must be at the same speed as the CPU frequency, using static random access memory (SRAM). The BIOS is written to die on the motherboard of a memory chip (ROM) program, can no longer power when the data can also be recorded, is the system when the first to read a small program. In addition, the firmware uses ROM to write software. The current BIOS is usually written in Flash or EEPROM.

Next talk about the video card . Also known as VGA, because each image displays a color that consumes memory, so there will be a memory capacity on the video card that will affect the screen resolution and color depth. The GPU is a 3D accelerated chip embedded in the graphics card. The specifications of the graphics card are led by early PCI to AGP, and then to Pci-express.

There are also hard drives and storage devices . Hard drives are made up of many platters, robotic arms, heads and spindle motors. The minimum storage unit of a disk is a sector, in the physical group composition surface, each sector size is fixed to 512bytes, the sector consists of a circle called the track, a track on a multi-drive can be composed of a cylinder, cylinder is generally divided into the smallest unit of disk. The storage capacity of the hard disk is calculated as the number of read heads x the number of cylinders per read Head x the number of sectors per cylinder X sector size, or headxcylinderxsectorx512bytes. The transmission interface of the disk is divided into: IDE interface, each line can connect two IDE devices, need to adjust the slip pin called master or Slave;sata interface, much smaller than the IDE interface, each SATA cable can only connect to a SATA device, the line is small to facilitate cooling and installation, The main use of this; SCSI interface, mainly used for workstations above the level of hard disk.

The PCI adapter card is also discussed. It is mainly used for the placement of functional cards with additional needs.

There are also motherboards . North Bridge is mainly responsible for the connection of CPU/RAM/VGA, and the Nan Qiao is responsible for the PCI interface and slower I/O devices. Integrated chip performance is usually weaker than independence, but at a low price. Each device has a unique I/O address, and each device can tell the CPU what the device is doing through an IRQ interrupt channel to facilitate the CPU's task allocation. The interrupt sharing technique is to turn off some unused peripheral interfaces to empty some of the IRQ to the really needed interface. CMOS is mainly used to record important parameters on the motherboard, it needs to spend electricity, the BIOS program can modify the data in the CMOS. The main board behind the connection interface devices are: PS/2 interface, USB interface, sound input, output and microphone, RJ-45 interface.

Again talking about the power supply . Energy conversion rate refers to the output power and input power ratio, the main board and the power supply interface is mainly 20pin and 24pin two kinds of specifications.

Finally, I talked about the choice of enough information . The speed of the computer is related to the slowest device in the overall system. System instability is common: system overclocking, power instability, memory load, system overheating and so on.

3. How data is represented

First, we talk about the digital system .

Then we talk about the text Coding System . The Common English encoding table is the ASCII system, each symbol will occupy 1B record. Chinese commonly used is big5 (simplified is gb2312), each Chinese character will occupy 2 B. The international development of the Unicode encoding system, also known as UTF8 or unified code.

4. Software program operation

First, we talk about the machine program and the compiler program .

Then talk about the operating system . The main operating system kernel is to manage the hardware and provide related capabilities, so the kernel program placed in the memory of the block is protected, and after the boot has been resident memory. The operating system's kernel was written directly to the hardware specifications, so the same operating system program could not run under a different hardware architecture. The operating system also provides an entire set of development interfaces, the system call layer. At least the kernel functions are: System call interface, program management, memory management, file system management, device driver. Note that drivers are provided by the vendor and are not related to the operating system developer, they just provide the development interface.

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"Brother Bird's Linux private cuisine-Basic Study (third edition)" (a)