CH7:儲存體

Memory address register(MAR)

The Memory Address Register (MAR) is a CPU register that either stores the memory address from which data will be fetched to the CPU or the address to which data will be sent and stored.

 

Memory buffer register(MBR)

A Memory Buffer Register (MBR) is the register in a computer's processor, or central processing unit, CPU, that stores the data being transferred to and from the immediate access store. It acts as a buffer allowing the processor and memory units to act independently without being affected by minor differences in operation. A data item will be copied to the MBR ready for use at the next clock cycle, when it can be either used by the processor or stored in main memory.

Program counter (PC)

The program counter (PC), commonly called the instruction pointer (IP) in Intel x86 and Itanium microprocessors, and sometimes called the instruction address register (IAR)or just part of the instruction sequencer, is a processor register that indicates where a computer is in its program sequence.






Cloud storage
Cloud storage is a model of networked online storage where data is stored in virtualized pools of storage which are generally hosted by third parties. Hosting companies operate large data centers, and people who require their data to be hosted buy or lease storage capacity from them. The data center operators, in the background, virtualize the resources according to the requirements of the customer and expose them as storage pools, which the customers can themselves use to store files or data objects. Physically, the resource may span across multiple servers.
Cloud storage services may be accessed through a web service application programming interface (API), or through a Web-based user interface.

Column Address Strobe (CAS)


Column Address Strobe (CAS) latency, or CL, is the delay time between the moment a memory controller tells the memory module to access a particular memory column on a RAM memory module, and the moment the data from given array location is available on the module's output pins. In general, the lower the CAS latency, the better.





IP(Instruction pointer)

An Internet Protocol address (IP address) is a numerical label assigned to each device (e.g., computer, printer) participating in a computer network that uses the Internet Protocol for communication.[1] An IP address serves two principal functions: host or network interface identification and location addressing. Its role has been characterized as follows: "A name indicates what we seek. An address indicates where it is. A route indicates how to get there.
In most processors, PC is incremented after fetching an instruction, and holds the memory address of (“points to”) the next instruction that would be executed. (In a processor where the incrementation precedes the fetch, PC points to the current instruction being executed.)
Instructions are usually fetched sequentially from memory, but control transfer instructions change the sequence by placing a new value in PC. These include branches (sometimes called jumps), subroutine calls, and returns. A transfer that is conditional on the truth of some assertion lets the computer follow a different sequence under different conditions.
A branch provides that the next instruction is fetched from somewhere else in memory. A subroutine call not only branches but saves the preceding contents of PC somewhere. A return retrieves the saved contents of PC and places it back in PC, resuming sequential execution with the instruction following the subroutine call.




ROM (Read-only memory)

Read-only memory (ROM) is a class of storage medium used in computers and other electronic devices. Data stored in ROM cannot be modified, or can be modified only slowly or with difficulty, so it is mainly used to distribute firmware (software that is very closely tied to specific hardware, and unlikely to need frequent updates).
In its stric⋯⋯test sense, ROM refers only to mask ROM (the oldest type of solid state ROM), which is fabricated with the desired data permanently stored in it, and thus can never be modified. Despite the simplicity, speed and economies of scale of mask ROM, field-programmability often make reprogrammable memories more flexible and inexpensive. As of 2007[update], actual ROM circuitry is therefore mainly used for applications such as microcode, and similar structures, on various kinds of processors.
Other types of non-volatile memory such as erasable programmable read only memory (EPROM) and electrically erasable programmable read-only memory (EEPROM or Flash ROM) are sometimes referred to, in an abbreviated way, as "read-only memory" (ROM); although these types of memory can be erased and re-programmed multiple times, writing to this memory takes longer and may require different procedures than reading the memory.[1] When used in this less precise way, "ROM" indicates a non-volatile memory which serves functions typically provided by mask ROM, such as storage of program code and nonvolatile data.
ROM is also useful for binary storage of cryptographic data, as it makes them difficult to replace, which may be desirable in order to enhance information security.
Read-only memory (Read-Only Memory, ROM) is a semiconductor memory, and its characteristics once the stored data can no longer change or delete the content will not disappear because the power is turned off.Require frequent changing programs or data in electronic or computer system, usually used to store.




Cache memory
A CPU cache is a cache used by the central processing unit of a computer to reduce the average time to access memory. The cache is a smaller, faster memory which stores copies of the data from the most frequently used main memory locations. As long as most memory accesses are cached memory locations, the average latency of memory accesses will be closer to the cache latency than to the latency of main memory.


NAS(Network-attached storage)

Network-attached storage (NAS) is file-level computer data storage connected to a computer network providing data access to heterogeneous clients. NAS not only operates as a file server, but is specialized for this task either by its hardware, software, or configuration of those elements. NAS is often made as a computer appliance – a specialized computer built from the ground up for storing and serving files – rather than simply a general purpose computer being used for the role.

RAS(Row Address Stobe)

Abbreviated RAS, a signal, or strobe, sent by the processor to a DRAM circuit to activate a row address. DRAM stores data in a series of rows and columns, similar in theory to a spreadsheet, and each cell where a data bit is stored exists in both a row and a column. A processor uses RAS and CAS (column address strobe) signals to retrieve data from DRAM. When data is needed, the processor activates the RAS line to specify the row where the data is needed, and then activates the CAS line to specify the column. Combined, the two signals locate the data stored in DRAM.