Noun Explanation (2)

(1) Itanium

Pentium and Itanium are Intel, Pentium for home machines, Itanium is the next generation server CPU, the new architecture mainly supports 64-bit systems.

Pentium, core and Celeron, these three are all Intel's CPU series code. Pentium is the earlier high-end products, now the basic offline, core is Pentium after the high-end successor, Celeron is low-end products, the main focus on the low-end consumer market.

Pentium e processor, in fact, the core cache capacity is reduced by half, the frequency is correspondingly reduced some, is the cheap version of the core. And now the popular comparison of the civilian Celeron is based on Pentium E, and then cut off half of the level two cache.

1. Celeron

A cheap Cpu-celeron (in Chinese called Celeron) was introduced in April 1998. The original Celeron has 266MHz, 300MHz two versions, and all use Covington Core, 0.35 micron process manufacturing, internal integration of 19 million transistors and 32KB first-class cache, operating voltage 2.0V, FSB 66MHz. Celeron and Pentiumⅱ, removed the L2 cache on the chip, although the move greatly reduced costs, but also because there is no level two cache, the microprocessor performance is greatly compromised, its integer performance is not even as Pentium MMX, the market reaction cold.

2. Pentium

The abbreviation of microprocessor is CPU, the central processing unit, is the core of the computer, every work that the computer completes is done under its command and intervention. The model of the CPU that the computer configures actually represents the basic performance level of the computer. At present, the main market is the multi-functional Pentium-class chip.

3. Core

Intel processor name, English name is core, server version of the development code is Woodcrest, the development of the desktop version of the code is Conroe, mobile version of the development code is merom. Divided into two-core, four-core, eight-core three kinds.

4. Itanium Itanium

Itanium (Itanium) Processor: 64-bit pioneer.

The Intel Itanium 2 processor is designed for demanding enterprise and technology applications.

The specially designed Intel Xeon processor meets the requirements for scalability (scalability), availability (availability), and manageability (manageability) in the market segment of high-performance workstations. Future faster clock speeds and a larger cache configuration will provide more space for compute, graphics processing, and ultra-high I/O load.

(2) Logical drive

A volume that is created in an extended disk partition on a basic master boot record (MBR) disk.

Logical drives are similar to primary partitions, except that each disk can have a maximum of four primary partitions, and the number of logical drives created on each disk is unrestricted. A logical drive can be formatted and assigned a drive letter. Logical drives are generally referred to as several partitions of a hard disk. You must partition a new hard disk before it starts to use it. In order to make better use of hard disk space, we usually divide its overall space into a number of areas, we look at the operating system on the hard disk, such as Windows "My Computer", we see "Local Disk (C)", "Local Disk (D)", "Local Disk (E)", and so on, it seems that there are multiple hard Multiple physical drives will also behave in the form above, in fact logically they are on a piece of hard disk partitions, which we call logical drives.

(3) NTFS and FAT32       

1.ntfs:new techonlogy File System new technology filesystem.
2.fat:file Allocation Table file allocation tables its significance lies in the management of the partition of the hard disk.     

The file allocation table, the FAT (Allocation table), is used to record the table where the file is located. It is very important for the use of the hard disk, if you lose the file allocation table, then the data on the hard disk cannot be located and can not be used.

Different operating systems are used differently, and in the operating system that is commonly used on personal computers,
DOS 6.x and the following versions and Windows 3.x use FAT16;
OS/2 use HPFS;
Windows NT uses NTFS;
ms-dos7.10/8.0 (Windows 95OSR2 and Windows 98 comes with DOS) and Rom-dos 7.x also provide FAT16 and FAT32 for users to choose from.

3. Why is it called FAT32
Windows95 OSR2 and Windows 98 began to support the FAT32 file system, which was an enhancement to the early DOS FAT16 file system, known as the FAT32 file system due to the file system core-the file allocation table fat expanded from 16 bits to 32 bits.

4. Logic Disk
　Using this format when a logical disk (a partition of a hard disk) is more than 512 megabytes, it is more efficient to store data, reduce the waste of hard disk space, and generally make programs run faster, using fewer computer systems, and therefore a highly effective system for storing files using large-capacity hard drives.

　A The FAT32 file system divides the space of the logical disk into three parts, the boot area (boot area), the File Allocation table area (fat area), and the data area. The boot area and file allocation table area are also called system zones.

(b) The boot zone occupies only one sector, saving the number of bytes per sector of the logical disk, the number of sectors corresponding to each cluster, and so on important parameters and boot records. Then there are 31 reserved sectors left. The boot area of the FAT16 file system occupies only one sector, and there are no reserved sectors.

(iii) The file allocation table has a total of two identical file allocation tables, because the storage space (cluster chain) of the file and the management of the free space are implemented through fat, fat is so important, save two so that the first damage, there is a second available. File system to the data area storage space is divided and managed by cluster, the cluster is the basic unit of space allocation and recovery, that is, a file always occupies a number of clusters, the file used by the last cluster of the remaining space is no longer used, but wasted.

5. About clusters

Statistically speaking, the average file wastes 0.5 clusters of space, the larger the cluster, the more wasted space when storing files, the lower the utilization rate. Therefore, the size of the cluster determines the utilization of the data area of the disk. The FAT16 system cluster number is represented by a 16-bit binary number, from 0002H to FFEFH available cluster numbers (fff0h to FFFFH are defined to indicate bad clusters, file end clusters, etc.), allowing the data area of each logical disk to be no more than FFEDH (65518) clusters. The FAT32 system cluster number is instead represented by a 32-bit binary number, roughly from 00000002H to FFFFFEFFH available cluster numbers. The Fat table records the usage of each cluster in sequential order, and is a kind of bit graph method. (a bit diagram is a binary representation of the use of a disk block in a disc.) When the value is "0", the corresponding disk block is idle, and for "1", the representation is already assigned. Some systems use "0" as the token allocated by the disk, and "1" as the idle flag. (They are essentially the same, both with one-bit status flags idle and allocated two cases.) All disk blocks on the disks have a bits corresponding to them, so that the bits corresponding to all the blocks constitute a set, called a bit diagram. ）
The use of each cluster is filled with 32-bit binary, not assigned to the corresponding position of the cluster to write 0; the corresponding position of the broken cluster is filled with a value other than 0, if the cluster is the last cluster of the file, the value entered is FFFFFF0FH, if the cluster is not the last cluster of the file, The value that is filled in is the cluster number of the next cluster that the file occupies, so that the clusters that occupy the file are formed into a single cluster chain, saved in the Fat table. 0000000H, 00000001H two cluster number is not used, its corresponding two DWORD position (8 bytes at the beginning of the Fat table) is used to hold the disk media type number. The size of the fat table is determined by the number of clusters in the data area of the logical disk, taking the entire number of sectors.

FAT32 is an upgraded version of FAT16, which uses a 32-bit file allocation table, greatly enhancing the ability to manage the disk, breaking the FAT16 limit of 2GB per partition capacity. After using the FAT32 partition format, the user can define a large hard disk as a partition without dividing it into several partitions, which greatly facilitates the management of the hard disk. Moreover, FAT32 has one of the biggest advantages: in a partition of not more than 8GB, the FAT32 partition format of each cluster capacity is fixed to 4kb, compared with FAT16, can greatly reduce the waste of hard disk space, improve the efficiency of hard disk utilization. Although it is less secure and more stable than NTFS, it has one of the biggest advantages: compatibility is good and almost all operating systems recognize the format, including DOS6.0, Win9x, WinNT, Win2000, and WinXP.

　FAT32: With the advent of large-capacity hard disk, starting from Windows98, FAT32 began to pop. It is an enhanced version of FAT16 and can support up to 2TB. (FAT32 uses a cluster smaller than FAT16, which effectively saves hard disk space).

Disadvantages

However, fat has a serious disadvantage: when the file is deleted and the new data is written, Fat does not organize the files into full fragments and then write, the long-term use will make the file information gradually dispersed, and slow down the reading and writing speed. Hard disk defragmentation is a workaround, but it must often be collated to keep the FAT file system efficient. There is the FAT32 partition because of design flaws, can not support more than 4GB of a single file.
Disk structure

Main boot area file allocation table #1 file allocation table #2 root directory all other information ... Disk space remaining

A FAT file system consists of four different parts.

1. Reserved sectors

At the beginning of the position. The first reserved sector is the boot area (partition boot record). It includes a region called the basic input and output parameter block (including some basic file system information, especially its type and other pointers to other sectors), usually including the operating system's startup calling code. The total number of reserved sectors is recorded in one parameter in the boot sector. Important information in the boot sector can be accessed by the operating system structure called drive parameter blocks in DOS and OS/2.

2.FAT Area

It contains two file allocation tables, which are considered for system redundancy, although it is rarely used, even disk repair tools rarely use it. It is a mapping table of partition information that indicates how the cluster is stored.

3. root directory Zone

It is a table of contents that stores file and directory information in the root directory. Under FAT32 it can exist anywhere in the partition, but in earlier versions it always follows the fat zone.

4. Data region

This is the actual area of file and directory data storage, which occupies the vast majority of the partitions. By simply adding the number of file links in fat you can arbitrarily increase the file size and number of subdirectories (as long as there are empty clusters present). However, it is important to note that each cluster can only be occupied by one file, so if there is a 1KB size file in a cluster of 32KB size, then 31KB of space will be wasted.
NTFS: The Microsoft Windows NT kernel's family of operating systems supports a disk format specifically designed for managing security features such as network and disk quotas, file encryption, and so on. NTFS also stores data files in clusters, but the size of the clusters in NTFS does not depend on the size of the disk or partition. Cluster-only shrinking reduces disk space waste and reduces the likelihood of disk fragmentation. NTFS supports file encryption management, providing users with a higher level of security assurance.

NTFS can make more efficient use of disk space, Support folder compression, and better security.
If you set up a multiboot system, the system disk must be FAT32, or multiboot is not supported.

The Windows system provides the partition format conversion tool Convert.exe.Convert.exe is a DOS command line program that comes with the Windows system, which allows you to convert FAT to NTFS directly without destroying the FAT file system as a whole. It is generally formatted as convert E:/fs:ntfs. All conversions will be completed after the system restarts.
In addition, you can also use the dedicated conversion tool: Hard disk lossless partitioning tool.
　　How to protect your files and folders under the NTFS system:

　　Because NTFS file partition format has good security, if you do not want your files on your hard disk to be called or viewed by someone else, using rights-controlled encryption is a very efficient method.
The Setup method is simple: Log in as an administrator, right-click the folder you want to encrypt, select Properties, and switch to the Security tab. The "Group of user Names" entry is set to allow access to users only administrator and themselves. Remove all other users. Save settings to exit.

In addition, you can give each user a detailed set of permissions, including the ability to set read permissions, write permissions, delete permissions, etc., so that the use of more flexible. You can also set permissions, control a disk,
Or the disk partition is only for your own use, so that no one else can see anything of yours.

With the continuous increase of hard disk capacity and the continuous emergence of large files, it is particularly important for file system to support large files and manage files. NTFS has an innate advantage in this regard. The FAT32 format can
The maximum supported files are only 2GB, and NTFS breaks this limit. This allows DVD-formatted movies to be completely copied to disk without worrying about breaking the limits.
NTFS format also has the advantage of file management, it produces more fragments than the FAT32 format, can make the file in a better order on the disk, the performance of the system to maintain stability.
NTFS file access permission settings are also very powerful, can easily set different permissions for different users, the security and privacy of the file is very good protection. Encryption is a major feature of the NTFS format,
can easily and quickly protect files, and its compression function can effectively save disk space.

Advantages:
NTFS supports file encryption and separate management capabilities to provide users with a higher level of security assurances.
NTFS has better disk compression performance, which can further meet the needs of small hard disk users.
NTFS supports large hard disks up to 2TB in size, and its performance does not degrade as disk capacity increases.

The NTFS partition format is generated following the Windows NT system, which has the notable advantage of being extremely secure and stable, which is not easy to produce file fragments in use, and is good for the space utilization of the hard disk and the speed of the software.

The NTFS format has many unique advantages, but it also has a fatal disadvantage that the disk file format cannot be recognized by other operating systems other than itself.

(4) Windows NT

Windows NT, the new technology Windows operating system (Windows new technology), is the core of the operating system introduced by Microsoft Corporation in 1993. Windows NT is based on the OS/2 NT basis. OS/2 was developed jointly by Microsoft and IBM and was divided into Microsoft OS/2 NT and IBM OS/2. IBM continued to provide the market with its previous version of OS/2 as the two sides collaborated later, while Microsoft renamed OS/2 NT as Windows NT, and in November 1988 began product development for "WinNT", the first generation of Windows NT 3.1. At the beginning of the development, "WinNT" was once thought to be the original version of the OS/2 3.0.

(5) Cursor mode

"Design patterns:elements of reusable object-oriented software" (i.e., the book "Designing Mode") by Erich Gamma, Richard Helm, Ralph Johnson and J Ohn Vlissides co-authored (addison-wesley,1995). These authors are often referred to as the "foursome (Gang of four)".

Iterator (Iterator) mode, also known as cursor mode. GOF provides a way to access individual elements of a container (container) object without exposing the object's internal details. The iterator pattern is visible from the definition and is for the container. Obviously, access to the container object inevitably involves a traversal algorithm. You can plug the Traversal method into the container object in a single brain, or not provide any traversal algorithms at all, so that the person who uses the container will implement it himself. Both of these situations seem to solve the problem.

The iterator pattern adds an iterator role between the customer and the container. With the addition of the iterator role, it is possible to avoid exposing the details inside the container, and to make the design conform to the "single responsibility Principle".

The following benefits are brought to the application of the container by the generation mode:

1) supports traversing a container role in different ways. Depending on the implementation method, there will be differences in effect.

2) simplifies the interface of the container. In Java collection, however, the container provides a traversal interface for extensibility.

3) Multiple traversal can be performed on the same container object. Because the traversal state is stored in each iterator object.

Scope of application of the iterator pattern:

1) Access the contents of a container object without exposing its internal representation.

2) supports multiple traversal of the container object.

3) provides a unified interface for traversing different container structures (polymorphic iterations).

STL is standard templates Library

Noun Explanation (2)