Secondary storage (or external memory) differs from primary storage, CPU is not directly accessible. Generally, your computer channel input / output access to secondary storage and transfers desired data using primary storage in the intermediate sector uses. Secondary storage data is not lost when the device off, or is unstable. Per unit, usually on an order of magnitude cheaper than primary storage. Consequently, modern computer systems typically an order of magnitude more secondary storage than primary storage and data is now kept there.
In modern computers, hard drive, as common as secondary storage is used. Information stored on the hard drive requires using byte-given common as some ms time, or thousandths of a second is. In contrast, the time for information stored in random access memory using a given byte is needed each other, or is measured in millionths of nanoseconds. It is very important to use solid state memory, magnetic storage rotating equipment differences: hard drive, one million different examples of times slower than memory. CD and DVD optical storage devices such as rotating, is used more often. Disk drive with disk once read / write head and the tour's interest under the right location, then the data on this subject are using information reaches very fast. As a result, in order to hide the first search time and rotational latency, data is transferred to disk and in large contiguous blocks.
When data resides on disk, block access to external memory latency to hide the design of efficient algorithms provides a ray of hope. Has been based on systematic or block access disk volume orders with fast random access, and refining criteria for the design of many efficient algorithms developed sequential and block access. Another way to reduce I / S bottleneck in the parallel disk access for many primary and secondary [2 is to increase bandwidth between the memory].
Other examples of secondary storage technologies are: flash memory (USB flash drive or like keys), floppy disk, magnetic tape, paper tape, punch cards, RAM disks and Iomega Zip free.
Secondary storage is usually a file format, files and directories for which data is formatted according to the event provides the necessary abstraction, providing additional information (called Metadata) owner of a specific file, use the time described, access is allowed , and other information.
Most computer operating systems use the concept of virtual memory, and allow the use of primary storage capacity in the system is physically available. As is done in main memory, the system at least (a swap file or page file) for secondary storage devices (pages) were cut, then it shows retrieved when needed. Many of these consultations are necessary secondary storage slow, overall system performance degrades as
Processor registers are located inside the processor. Each register typically holds a word of data (often 32 or 64 bits). Mathematics and logic unit CPU instructions directed to various calculations or other operations on such data (or use it). Register of all forms of computer data storage are technically among the fastest.
Ultra fast and very slow main memory cache processor register one intermediate layer between. This occurs only for enhancing performance. Most actively used information in main memory is duplicated in the cache, which is fast, but very small capacity. On the other hand is more, slow, but much larger than processor registers. Configuration also commonly used multi-level cache - Primary cache is being hierarchical small, located within the fastest processor and the secondary cache, is being a bit big and slow.
Directly or indirectly from the main memory through a memory bus is related to CPU. In fact, two buses (not on diagram): an address bus and a data bus. The first one addresses a number of CPU's bus passes through a number called a memory address, which indicates the desired location of data. Just use the data it reads or writes data. In addition, a memory management unit (MMU) CPU and Ram is among a small tool recalculating the actual memory address, for example, virtual memory or other functions to provide an abstract.
RAM used for the type of primary storage are volatile as (cleared up), the same instructions for storage with the team have read any source that computer to start. Therefore, non-volatile primary with a small startup program (BIOS) storage for boot computers, ie using one big program RAM read and escape is the beginning of nonvolatile secondary storage. Used for this purpose a non-volatile ROM technology is said, is to read-only memory (ROM type in terms of the random access is enabled as some may be confused).
Several types of "Ram" - not really read only, updated as possible, but slow and memory must be erased before it again in large part may be, is written. Some embedded systems run programs directly from ROM (or similar), because these programs often do not change. Not standard equipment in stores non-ROM original program, but secondary storage that is nonvolatile, so great ability, and otherwise use the expensive
In modern computers, hard drive, as common as secondary storage is used. Information stored on the hard drive requires using byte-given common as some ms time, or thousandths of a second is. In contrast, the time for information stored in random access memory using a given byte is needed each other, or is measured in millionths of nanoseconds. It is very important to use solid state memory, magnetic storage rotating equipment differences: hard drive, one million different examples of times slower than memory. CD and DVD optical storage devices such as rotating, is used more often. Disk drive with disk once read / write head and the tour's interest under the right location, then the data on this subject are using information reaches very fast. As a result, in order to hide the first search time and rotational latency, data is transferred to disk and in large contiguous blocks.
When data resides on disk, block access to external memory latency to hide the design of efficient algorithms provides a ray of hope. Has been based on systematic or block access disk volume orders with fast random access, and refining criteria for the design of many efficient algorithms developed sequential and block access. Another way to reduce I / S bottleneck in the parallel disk access for many primary and secondary [2 is to increase bandwidth between the memory].
Other examples of secondary storage technologies are: flash memory (USB flash drive or like keys), floppy disk, magnetic tape, paper tape, punch cards, RAM disks and Iomega Zip free.
Secondary storage is usually a file format, files and directories for which data is formatted according to the event provides the necessary abstraction, providing additional information (called Metadata) owner of a specific file, use the time described, access is allowed , and other information.
Most computer operating systems use the concept of virtual memory, and allow the use of primary storage capacity in the system is physically available. As is done in main memory, the system at least (a swap file or page file) for secondary storage devices (pages) were cut, then it shows retrieved when needed. Many of these consultations are necessary secondary storage slow, overall system performance degrades as
Processor registers are located inside the processor. Each register typically holds a word of data (often 32 or 64 bits). Mathematics and logic unit CPU instructions directed to various calculations or other operations on such data (or use it). Register of all forms of computer data storage are technically among the fastest.
Ultra fast and very slow main memory cache processor register one intermediate layer between. This occurs only for enhancing performance. Most actively used information in main memory is duplicated in the cache, which is fast, but very small capacity. On the other hand is more, slow, but much larger than processor registers. Configuration also commonly used multi-level cache - Primary cache is being hierarchical small, located within the fastest processor and the secondary cache, is being a bit big and slow.
Directly or indirectly from the main memory through a memory bus is related to CPU. In fact, two buses (not on diagram): an address bus and a data bus. The first one addresses a number of CPU's bus passes through a number called a memory address, which indicates the desired location of data. Just use the data it reads or writes data. In addition, a memory management unit (MMU) CPU and Ram is among a small tool recalculating the actual memory address, for example, virtual memory or other functions to provide an abstract.
RAM used for the type of primary storage are volatile as (cleared up), the same instructions for storage with the team have read any source that computer to start. Therefore, non-volatile primary with a small startup program (BIOS) storage for boot computers, ie using one big program RAM read and escape is the beginning of nonvolatile secondary storage. Used for this purpose a non-volatile ROM technology is said, is to read-only memory (ROM type in terms of the random access is enabled as some may be confused).
Several types of "Ram" - not really read only, updated as possible, but slow and memory must be erased before it again in large part may be, is written. Some embedded systems run programs directly from ROM (or similar), because these programs often do not change. Not standard equipment in stores non-ROM original program, but secondary storage that is nonvolatile, so great ability, and otherwise use the expensive
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