RAM(random access memory)

RAM-random access memory.The content of the storage unit can be on-demand optional remove or deposit and access speed and storage unit position-independent memory. This memory will be lost in case of a power cut, so its store content is mainly used for storage short time use process. According to the different information stored, random access memory and divided into Static random access memory (RAM) and an SRAM Static, Dynamic RAM (Dynamic RAM, DRAM).

characteristics

Random access

The so-called "random access", it refers to the when memory is read or written messages, by the time needed and this period of information location is irrelevant. Relative, read or written order Access (Sequential Access) storage device, its need information when the time and location will have relations (such as tape).

nonvolatile

When the power supply closing RAM cannot retain data. If need to save data, we must put them into static random access memory

A long-term storage devices (such as hard disk). RAM and ROM, the biggest difference between compared when power is stored in RAM after the above data will automatically disappear, and ROM can't.

High access speed

Modern random access memory is almost all access equipment written and read the fastest, take save delay also and other involving machinery operation compared the storage devices, also appear insignificant.

Need a refresh

Modern random access memory rely on capacitors store data. Capacitor after batteries represents 1 (binary), not charging representatives 0. Because of capacitor is more or less creepage situation, if not for special processing, data will gradually over time and erosion. Refresh refers to the state regularly read capacitor, then according to its original state again for capacitor recharge, make up lost charge. Need a refresh explains random access memory volatile.

Static sensitive to

As with other fine integrated circuits, random access memory of electrostatic very sensitive to the environment. Electrostatic can interfere with the memory of the charge that cause within capacitor data loss, even burn out circuit. Therefore before touch random access memory, should first touch a metal grounded.

difference

Random access memory

ROM - campaigns for with read-only memory

(1) simply said, in computers, RAM and ROM is data storage. RAM is random access memory, its characteristic is easy volatile, namely off electricity amnesia. ROM usually refers to curing memory (write once read repeatedly), it features and RAM instead. ROM one-time solidifying, light and distributes erasing and electricity erased rewrite two types. For example, if suddenly is without saving power or closed files, so ROM can random to save before the document but no storage RAM makes no save files before disappearing.

memory

In computer composition structure, there is a very important part, is memory. Memory is used to store programs and data components, for the computer, it has a memory, just have the memory function, to ensure normal work. There are many kinds of memory, according to its use can divide give priority to storage and auxiliary storage, main memory in memory (also called as memory), auxiliary storage also called external storage (hereinafter referred to WaiCun). WaiCun is usually magnetic media or CD, like hard disk, floppy disks, tapes, CDS, etc, which can long-term preservation information, and not dependent on electricity to save the information, but driven by mechanical components, compared with the CPU speed becomes much more slowly. Memory refers to the storage unit is the motherboard, CPU is directly with communication and using its data storage components, deposit is currently use (i.e. the execution of the data and programs,) of its physical essence is a group of or more groups have data input/output and data storage function integrated circuits, memory used only to temporarily store data and programs, once the power off or happen without electricity, and, in one of the program and data would be lost.

From the beginning, a computer memory. Memory development today also experienced many technical improvement, from the earliest DRAM until FPMDRAM, EDODRAM, the speed of SDRAM, memory has been on the rise and capacity is also in constant increase. Today, the server is used mainly what kind of memory? At present, IA architecture server commonly used are REGISTERED rapid cycle random access memory

ECCSDRAM.

Since the memory is used for storing is currently use (i.e. the execution of the data and programs,) so how did it work? Normally we mentioned the computer's memory refers to the dynamic memory (namely DRAM), dynamic memory of so-called "dynamic", refers to when we will data writing DRAM, over a period of time after data will be lost, therefore, need an extra memory refresh operation set circuit. Specific working process is this: a DRAM of storage unit storage is 0 or 1 depends on whether there is a charge, capacitance, without charge charge representative 1 representing 0. But time grows, representative 1 capacitance can discharge, representing the capacitance will absorb charge 2-0, this is data loss reasons; Refresh operation regularly check of capacitance, if the power is greater than full 1/2, argues that its representative 1, and the capacitance batteries; If power less than 1/2, argues that its representatives 0, and the capacitance discharge, through which to keep data continuity.