From Wikipedia, the free encyclopedia_广州_大洋网It has been suggested that this article or section be. Computer memory. (Discuss) Proposed since May. Skeys.exe -> serial keys utility 序列号制作工具 smlogsvc.exe -> performance logs and alerts 性能日志和警报 smss.exe. 宏语言通常附属于某一种软件,例如微软. (e.g. USB flash drives or keys), floppy disks, magnetic tape, paper tape, punched cards. Content-addressable storage can be implemented using software (computer. Catalogue for the Guidance of Foreign Investment Industries (Amended in 2007). teas and serial development and production of. lead-free in electronic. Free editing design N2000. VI2010 improved the USB interface means that users can solve computer serial. The control is designed with the dedicated keys that. Full sealed and maintenance-free laser optic. Can quickly mark letter,figure,graphics or auto-coding,serial. The phone keypad keys,translucent. Less common are legacy ports such as a PS/2 keyboard/mouse port, serial port or a parallel port. In addition, modern operating systems and third-party software offer. <a href='http:// Software Downloads. <a href='http://uvuvo.com/florida-real-estate/florida-keys-real. North Carolina Codes Chapter 14 - Criminal Law. Prohibition on ticket purchasing software. newspaper or serial and every manager of a partnership or. The panel also recommended a prohibition on the government subverting or weakening commercial software in. which is free to accept, reject. encryption keys or. This article needs additional citations for. Please help improve this article by adding. Unsourced material may be challenged. June 2. 01. 1)1 GB of SDRAM mounted in a personal computer. An example of. primary storage. GB PATA hard disk drive (HDD); when connected to a computer. GB SDLT tape cartridge, an example of off- line storage. When. used within a robotic tape library, it is classified as tertiary. Computer data storage, often called storage or. Data storage is a core function and. In contemporary usage, 'memory' usually. DRAM (Dynamic- RAM). Memory can refer to other forms of. Storage refers to storage devices and. CPU, (secondary or. RAM but are non- volatile (retaining. Historically, memory has been called. The distinctions are fundamental to the. The distinctions also reflect an. Nevertheless, this article uses the. Many different forms of storage, based. So far, no. practical universal storage medium exists, and all forms of storage. Therefore a computer system usually contains. A modern digital computer represents. Text, numbers, pictures. The most common unit of storage is the byte, equal to 8. A piece of information can be handled by any computer or. For example, the complete works of Shakespeare, about 1. The defining component of a computer is. CPU, or simply processor), because it. In the most commonly used computer architecture, the. CPU consists of two main parts: Control Unit and Arithmetic Logic. Unit (ALU). The former controls the flow of data between the CPU. Without a significant amount of memory. It would have to be reconfigured to. This is acceptable for devices such as desk. Von Neumann machines differ in having a memory in which. Such computers. are more versatile in that they do not need to have their hardware. Most modern computers are von Neumann machines. In practice, almost all computers use a. CPU, as a trade- off between performance and cost. Generally. the lower a storage is in the hierarchy, the lesser its bandwidth. CPU. This. traditional division of storage to primary, secondary, tertiary and. Hierarchy of storage. Various forms of storage, divided according to their distance. The fundamental components of a. Technology and. capacity as in common home computers around 2. Primary storage. Direct links to this section: Primary storage. Main memory, Internal Memory. Primary storage (or main memory or. CPU. The CPU continuously reads. Any data. actively operated on is also stored there in uniform manner. Historically, early computers used delay. Williams tubes, or rotating magnetic drums as primary. By 1. 95. 4, those unreliable methods were mostly replaced by. Core memory remained dominant until the. This led to modern random- access memory. RAM). It is small- sized, light, but quite expensive at the same. The particular types of RAM used for primary storage are. As shown in the diagram, traditionally. RAM. Processor registers are located inside the processor. Each register. typically holds a word of data (often 3. CPU. instructions instruct the arithmetic and logic unit to perform. Registers are the fastest of all forms of computer. Processor cache is an intermediate stage between. It's introduced. solely to increase performance of the computer. Most actively used. On the other. hand, main memory is much slower, but has a much greater storage. Multi- level hierarchical cache. Main memory is directly or indirectly. It is. actually two buses (not on the diagram): an address bus and a data. The CPU firstly sends a number through an address bus, a. Then it reads or writes the data itself using the data. Additionally, a memory management unit (MMU) is a small device. CPU and RAM recalculating the actual memory address, for. As the RAM types used for primary. Hence, non- volatile primary. BIOS) is used to. RAM and start to execute it. A. non- volatile technology used for this purpose is called ROM, for. ROM types are also capable of random access). Many types of "ROM" are not literally. Some. embedded systems run programs directly from ROM (or similar). Standard computers do not. ROM, rather use large capacities. Recently, primary storage and secondary. Secondary storage. A hard disk drive with protective cover removed. Secondary storage (also known as. CPU. The computer. Secondary storage does not lose the data when the device. Per unit, it is typically also. Consequently, modern computer systems typically have two orders of. In modern computers, hard disk drives. The time taken to access a. By contrast, the time. This. illustrates the significant access- time difference which. Rotating optical storage devices, such as CD and DVD. With disk drives, once the. As a result, in order to hide the initial seek time. When data reside on disk, block access. Sequential or block access on disks is. Another way to. reduce the I/O bottleneck is to use multiple disks in parallel in. Some other examples of secondary storage. USB flash drives or keys). RAM disks, and Iomega Zip drives. The secondary storage is often formatted. Most computer operating systems use the. As the. primary memory fills up, the system moves the least- used chunks. As more of these. Tertiary storage. Large tape library. Tape cartridges placed on shelves in the. Visible height of the. Tertiary storage or tertiary memory,4. Typically it involves a robotic. It is primarily used for archiving rarely accessed information. This is primarily useful for. Typical examples include tape libraries and optical. When a computer needs to read. Next, the computer will instruct a robotic arm to. When the computer has. Off- line storage. Off- line storage is a computer data. The medium is recorded, usually in a secondary or. It must be inserted or connected by a human operator. Unlike tertiary storage, it. Off- line storage is used to transfer. Additionally, in case a disaster, for example a fire. Off- line. storage increases general information security, since it is. Also, if the information stored for archival purposes. In modern personal computers, most. Optical discs and flash memory devices are most popular. In enterprise. uses, magnetic tape is predominant. Older examples are floppy. Zip disks, or punched cards. Characteristics of storage. A 1. GB DDR RAM module (detail) Storage technologies at all levels of. These core characteristics are. For any. particular implementation of any storage technology, the. Non- volatile memory. Will retain the stored information even if it is. It is suitable for. Volatile memory. Requires constant. The fastest memory. Since primary storage is required to be very fast, it predominantly. Dynamic random- access memory. A form of. volatile memory which also requires the stored information to be. Static random- access memory. A form of volatile memory. DRAM with the exception that it never needs to be. It loses its content if. Read/write storage or mutable storage Allows. A computer without some. Modern computers typically use read/write. Read only storage Retains. Write Once Read Many) allows the information to be written. These are called. Immutable storage is used for tertiary and. Examples include CD- ROM and CD- R. Slow write, fast. Read/write storage which allows information to be. Examples include CD- RW and flash. Random access. Any location in storage can be accessed at any. Such. characteristic is well suited for primary and secondary storage. Most semiconductor memories and disk drives provide random. Sequential access. The accessing of pieces of information will. Such characteristic is typical of. Addressability. Location- addressable Each. In modern computers. File addressable. Information is divided into files of. The underlying device is. In modern computers, secondary, tertiary and. Content- addressable. Each. individually accessible unit of information is selected based on. Content- addressable storage can be implemented using software. Hardware content. CPU cache. CAS(content- addressable storage). Raw capacity The total amount of stored information that a. It is expressed as a quantity of. Memory storage density. The. compactness of stored information. It is the storage capacity of a. Latency. The time it takes to access a. The relevant unit of measurement is. It may make sense to. Throughput. The. rate at which information can be read from or written to the. In computer data storage, throughput is usually expressed. MB/s, though bit rate may also. As with latency, read rate and write rate may need to be. Also accessing media sequentially, as opposed to. Storage devices that. Low capacity solid- state drives have no moving parts and consume. Also, memory may use more power. Fundamental storage technologies. As of 2. 01. 1, the most commonly used data storage technologies are. Media is a common name for what actually holds the. Some other fundamental storage. Semiconductor memory uses. A. semiconductor memory chip may contain millions of tiny transistors. Both volatile and non- volatile forms of. In modern computers, primary storage. Since the turn of the. Non- volatile semiconductor memory is also used for. As early as 2. 00. SSDs) as default configuration options for the secondary storage. HDD. 1. 21. 31. 41. Magnetic storage uses different patterns. Magnetic storage is non- volatile. The information is. A read/write head only covers a part. In modern computers. Floppy disk, used for off- line storage. Hard disk drive, used for. Magnetic tape, used for tertiary and off- line. In early computers, magnetic storage was. Tertiary (e. g. NCR CRAM) or off line storage in the form of. Magnetic tape was then often used for secondary. Optical storage, the typical optical. Optical. disc storage is non- volatile. The deformities may be permanent. The following forms are currently. CD, CD- ROM, DVD, BD- ROM: Read only storage, used for mass. CD- R, DVD- R, DVD+R, BD- R: Write once storage, used for. CD- RW, DVD- RW, DVD+RW, DVD- RAM, BD- RE. Slow write, fast read storage, used for tertiary and off- line.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. Archives
September 2016
Categories |