Brother Bird's Linux private Cuisine 0th Chapter

The CPU reads data from main memory and controls and calculates it through a micro-instruction set. The data in the main memory is transmitted from the input unit, and the data processed by the CPU must be written back to the main memory first, and the final data is transferred from the main memory to the output unit.
Memory, also known as main storage, is the CPU can directly address the memory space, made of semiconductor devices. Memory is characterized by a fast access speed. Memory is the main part of the computer, and it is relative to the external memory.
There are many kinds of memory, according to its use can be divided into main memory and auxiliary memory, hard disk and CD-ROM, USB stick belongs to auxiliary memory.
The type of CPU is differentiated by instruction set
Instruction set is mainly divided into thin instruction set RISC and complex instruction set CISC
The streamlined instruction set is fast and performs complex functions with a simple instruction combination. The main implementation of this type of instruction set is the ARM architecture on the mobile phone, such as Sun Company's SPARC series, IBM's Power Architecture (including PowerPC) series
The number of complex instruction set directives is numerous and complex, and the length of each instruction is not the same. Because instruction execution is more complex, each instruction takes a long time, but each individual instruction can handle a richer amount of work. Common CISC Micro-instruction set CPU mainly has AMD, Intel, VIA and so on x86 architecture CPU
The CPU's instruction cycle often uses units such as MHz or GHz, which is actually one of the seconds. In the network transmission aspect, because the network uses the bit unit, therefore the network commonly uses the unit to be Mbps is Mbits per second, namely is each second how many Mbit
About Motherboard: Motherboard mainly includes CPU north-South bridge chip (bus chipset) main memory disk adapter interface
North and South Bridge chip components are connected through the northern bridges and the Nan Qiao, and then connected to the CPU to deal with the chip is the main board on the motherboard from the CPU closest chip, this is mainly considering the bridge between the chip and the processor communication is the most close, in order to improve the communication performance and shorten the transmission distance. The South Bridge chip is responsible for communication between I/O buses, such as PCI bus, USB, LAN, ATA
Now the motherboard chipset in the number of North bridge chips far more than the South Bridge chip. It's like a group of people working on a continuous operation, if there are individuals in this group who are particularly fast or slow, they will cause a lot of things to be done in front or behind. That is to say, this group of people better be able to be consistent and better speed! Therefore, the speed of the CPU and the external components should be consistent in theory should be good.
Octave overclocking with FSB the so-called FSB refers to the speed at which the CPU and the external components transmit data, and the multiplier is a multiple of the CPU used to speed up the work efficiency, which is multiplied by the CPU's frequency speed. The frequency is 3.0GHz, and FSB is 333MHz, so the octave is 9 times times! (3.0g=333mx9, where 1g=1000m) like the above 3.0GHz CPU if you want to overclock, you can adjust his FSB 333MHz to 400MHz, but so that the entire motherboard of the operating frequency of each component will be increased to 1.333 times times (4/3).

32-bit and 64-bit
The front-end bus represents the transmission speed of the CPU and North Bridge chip.
As for the FSB and the front-end bus, the bridge supports the frequency we call the front-end bus speed (FRONTSIDEBUS,FSB), and the number of bits per transmission is the bus width. The so-called bus bandwidth is: "FSBX bus width"/8 is the maximum amount of data that can be transmitted per second. The current common bus width is 32/64 bits (bits).
On the computer motherboard, CPU-based, memory and a variety of peripheral devices supplemented by a number of devices to work together. The communication between these devices, the exchange of data, must be correct, the minutes are not bad. Therefore, they must have a fixed clock to do the time correction, coordination or reference. This clock is generated by the clock generator on the motherboard, which is called the FSB.
Before the two are the same frequency, with the QDR, super-line after the difference between the front-end bus is the CPU and North Bridge data exchange speed, FSB mainly with memory, PCI and other data exchange speed.
Local bus

After entering the PC, the graphical user interface (GUI) represented by Windows requires high-speed graphics and I/O processing capabilities. This not only requires the graphics adapter card to improve its performance, but also the speed of the bus challenges. In fact, the speed of the peripheral has been greatly improved, such as the data transmission between the hard disk and the controller has reached more than 10mb/s, graphics controller and display data transmission rate also reached 69mb/s. It is generally assumed that the I/O bus should be at multiple times the speed of the peripheral. Therefore, the original Isa, EISA has been far from adapting to the requirements, and become the main bottleneck of the whole system.

Local bus is a major development of PC architecture. It breaks the bottleneck of data I/O and makes the function of the high-performance CPU fully realized. Structurally, the so-called local bus is the one-level bus or management layer that is added between the ISA bus and the CPU bus. This allows some high-speed peripherals, cards, hard disk controllers, and so on from the ISA bus to be directly attached to the CPU bus via the local bus, so that it matches the high-speed CPU bus.

With PCI bus, the data width is upgraded to 64-bit, the bus frequency is 33.3MHZ, the data transmission rate (bandwidth) can reach 266mb/s. So the use of PCI bus greatly solves the data I/O bottleneck, so that the computer better performance.
The system bus is also called the internal bus or board-level bus. Because the bus is used to connect the various functional components of a microcomputer to form a complete microcomputer system, so called the system bus. The system bus is the most important bus in the microcomputer system, and what people usually refer to as the microcomputer bus is the system bus, such as PC Bus, at bus (ISA bus), PCI bus, etc.
Similar to the bus width, the amount of data that the CPU can handle each time is called the word Group size (wordsize) Maybe your bus width is 64 bits, but the CPU is 32 bit smaller than the bus width because the CPU can parse the amount of data each time, so the amount of data transmitted by the main memory is limited.
The primary memory of a PC's main memory is the dynamic random access memory, which is the random access memory, DRAM, which can be recorded and used only when powered on, and the data disappears after the power outage. So we also call this RAM a volatile memory. Usually the larger the memory represents the faster the system, which is because the system does not often
Frees some internal memory data. To the server, the capacity of the main memory is sometimes more important than the speed of the CPU!
Theoretically, the FSB of the CPU and the main memory should be the same. However, because of technical improvements, the frequency of both
Will not be the same, but the FSB should be consistent better.
In addition to the main memory, in fact, there is a lot of memory in the entire personal computer Oh! The most we know is that
Second-level cache within the CPU. We now know that the CPU data is provided by the main memory, but the main memory data is
Sent to the CPU via the North Bridge. If some very common programs or data can be placed inside the CPU, then the CPU data read
No need to go through the North Bridge! For the performance of the can not be greatly improved? This is the design concept for the second-level cache.
Because the second-tier cache is integrated into the CPU, the L2 memory must be at the same speed as the CPU frequency. Use
DRAM is not able to achieve this frequency speed, at this time need to static random access memory (static
SRAM) to help.
Read-only memory (ROM)
The components on the motherboard are very numerous, and the parameters of each component are also adjustable. For example, the frequency of CPU and memory can be
If there is a built-in network card or a display adapter on the motherboard, the function is to start the
is recorded on a chip called CMOS on top of the motherboard
The BIOS (Basic Input Output System) is a set of programs that are written to die on top of the motherboard
In a memory chip, this memory chip can also record the data when there is no power, that is, read only memory (read only)
Memory, ROM). ROM is a non-volatile memory. In addition, the BIOS is very important to the PC because
For he is the system in the boot when the first will go to read a small program Oh!
Is that the speed of computer development is too fast, so the BIOS program code may also need to be modified in moderation, so you will be in a lot of main
Board official website to find the BIOS update Ah! However, the BIOS originally used a ROM that cannot be rewritten, so it cannot be fixed at all
BIOS Program Code! For this reason, the current BIOS is usually written like Flash (Flash) or EEPROM
The display adapter, also known as the VGA (Video graphics Array), plays a critical role in the display of graphic images. So so
The display of the graphic image is focused on resolution and color depth, because each image displays a color that consumes memory and therefore displays
The adapter will have a memory capacity, the memory capacity of this display adapter will affect the end of your screen resolution and color depth
, Oh!
The display adapter is mainly through the North Bridge chip and CPU, main memory and other communication.
Assuming your desktop uses 1024x768 resolution and use full color (3bytes per pixel), would you
How much memory does the display adapter need at least to use such a color?
For:
Because there will be 786,432 pixels in the 1024x768 resolution, each pixel takes up 3bytes, so there is a total
More than 2.25MBytes! However, if you consider the screen update rate (the number of screens per second), the display adapter's
The larger the memory, the better!
The actual data are written on disk disks with magnetic material, and read-write is mainly through the reading Head (head) on the mechanical arm to achieve
Yes. In practice, the spindle motor rotates the disk disc, and then the mechanical arm stretches to allow the read head to read and write on the disk drive.
When calculating the storage capacity of the entire hard disk, a simple formula is: "Number of headers * Number of magnetic poles per header *
Number of sectors per magnetic column * Sector capacity ", unit converted to" header * Cylinder/header *
Secter/cylinder * 512bytes/secter ", the simple wording is as follows: Head x cylinder x Sector x Bytes.
However, it is important to note that the average hard disk manufacturer shows the capacity of the hard disk, mostly in decimal numbers, so the market for 500GB
Hard disk, theoretically only about 460GBytes of capacity Oh!
The interface of the hard disk and the host has the IDE interface SATA Interface SCSI interface
Buffer memory
The hard disk contains a buffer memory, which can be used to quickly pick up the data in the hard drive to speed up the system
Read performance. Usually the larger the buffer memory, the better, because the buffer memory speed than the data from the hard disk to be found
It's going to be a lot quicker! At present, the mainstream products can reach about 16MB of memory size OH.
We talked a little bit about the PCI interface in the previous display of the adapter, and there are actually quite a few components that are transmitted using the PCI interface,
such as network cards, sound cards, special function cards, and so on.
The motherboard is responsible for communication between the various computer components, but there are too many computer components, output/input/different storage devices, etc.
And so on, motherboard chipset How to know how to be responsible for communication? This time you need to use the so-called I/O address and IRQ!
The I/O address is a bit like the house number of each device, and each device has his own address, which in general cannot be used by two devices
The same I/O address, or the system will not know how to operate the two devices. In addition to the I/O address, there is an IRQ
Break (Interrupt) this boom.
If the I/O address wants to be the house number of each device, then the IRQ can be thought of as the individual numbers connected to the message Center (CPU)
Special path! Each device can inform the CPU of the operation of the device through an IRQ interrupt channel to facilitate the CPU to work
Tasks to match
The operating system (Operating system, OS) is actually a set of programs that focus on managing all of the computer's activities to
And all the hardware in the drive system we just talked about the computer without software is just a heap of scrap, then the function of the operating system is to let
The CPU can start judging the logic and arithmetic values, allowing the main memory to start loading/reading data and program code, allowing the hard disk to start being accessed, allowing the network card to start transmitting data, allowing all the perimeter to start running, and so on. In summary, all of the hardware's actions must be
To get through this operating system.
The above function is the core of the operating system (Kernel).
Systems calls (System call)
Since my hardware is managed by the core, then if I want to develop the software, it will naturally have to refer to the core of the relevant work
Yes! Well! This is not from the original reference hardware function into a reference core function, or very troublesome Ah! There is no simpler side
The Law!
To solve this problem, the operating system usually provides an entire set of development interfaces for engineers to develop software! As long as the engineer follows the
Development interface It's easy to develop software! For example, we learn the C programming language as long as the C program language function can be referenced,
There is no need to consider other core related functions, because the core system calling interface will actively translate the syntax of C programming language into
The core can understand the task function, the core will be able to smoothly run the program!
Since the core is mainly in charge of the whole computer system related resources allocation and management, then we know that the whole computer system is the most important
is the CPU and the main memory, so the core must have at least these features:
X system call Interface (interface)
Just talked about, this is to facilitate the program developers can easily through the communication with the core, the hardware resources further benefit
It is necessary to have this simple interface to facilitate program developers.
X program Management (Process Control)
Have you ever heard of the so-called "multitasking environment"? A computer may have a lot of work at the same time running to the CPU waiting for operations
Management, the core of this time must be able to control the work, so that the CPU resources for effective allocation of the line! In addition, a good
The CPU scheduling mechanism (which is the order in which the CPU works first) will effectively speed up the overall system performance.
X memory Management (management)
Control the memory management of the whole system, this memory control is very important, because all the program code and data of the system must be
To be stored in memory first. Typically, the core provides the functionality of virtual memory that can provide memory replacement when memory is low
(Swap) function.
x File System Management (Filesystem management)
File system management, such as data input and output (I/O) and so on work! There are different file formats for support and so on,
If your core does not recognize a file system, then you will not be able to use the file format files! For example, Windows
98 do not know the NTFS file format of the hard disk;
X-Device driver (device drivers)
As mentioned above, the hardware management is one of the core work, of course, the device driver is the core needs
Do the thing! Fortunately, there are now so-called "loadable modules" function, you can edit the driver into a module, you do not need to
To re-compile the core!
Operating system and drivers
Frankly speaking, the driver can be said to be a very important part of the operating system! However, the hardware continues to progress! Package
Including motherboards, display adapters, hard drives, and more. The newer hardware that is later introduced, such as the display adapter, our operating system when
But I don't know you! How does the operating system drive this new display adapter? To overcome this problem, the operating system usually
For a development interface to the hardware developers, so that they can design according to this interface can drive their hardware "drivers", such as
This will allow the user to drive the display adapter on their operating system as long as the driver is installed. Drivers are provided by the vendor, regardless of the operating system developer.

Brother Bird's Linux private Cuisine 0th Chapter