Discuss the various types of memory devices, Electrical Engineering

Discuss the various types of memory devices that you are familiar with.

All of the memory utilized as main store in a modern computer is implemented like semiconductors fabricated upon wafers of silicon. Semiconductor memory is quick and easy to utilize. To fulfil the requirements of modern computer systems this is becoming increasingly dense (additional bits per chip) and cheap. 

A semiconductor memory chip contains a large number of cells organized in an array, and the logic essential to access any array in the cell simply. Semi-conductor memory may be classed as per to the mechanism used by each cell to store data. This simplest type of memory is termed as static memory. Within static memory each cell uses a flip-flop made by four or six transistors. The data in all cells is remembered till the power is switched off. Static memory is easy to utilize and reliable, but is slow, relatively bulky and expensive. Therefore most computer systems use dynamic memory as their main store. Dynamic memory utilizes just a single transistor per cell; therefore it is denser, cheaper and faster.

Unfortunately all cells gradually forget the data stored in this, and so extra circuitry should be used to continually refresh the cells. Memory, regarding computers, most normally refers to semiconductor devices whose contents can be accessed (that is read and written to) at extremely high speeds. The major characteristics of semiconductor memory are based upon capacity, access time and organization. Within microprocessor-based systems semiconductor memories are used as primary storage for data and code.

In contrasts with storage, that (1) retains programs and data in spite of of whether they are currently in utilize or not, (2) retains programs and data after the power supply has been detached, (3) has much slower access speeds and (4) has a very larger capacity (and a much lower cost). Illustrations of storage devices are hard disk drives (HDD), optical disks, floppy disks, (for example: CDROMS and DVDs) and magnetic tape. 

The term memory as used in a computer context originally termed as the magnetic core memory devices which were used beginning in the 1950s. This was subsequently applied to the semiconductor memory devices as replaced core memories in the year 1970s. 

Computer memory today has mainly of dynamic random access memory (DRAM) chips which have been built into multi-chip modules which are, in turn, plugged in slots on the motherboard (the major circuit board on workstations and personal computers). This DRAM is generally referred to as random access memory, and this constitutes the main memory of a computer. 

The random in random access memory consider to the fact as any location in this memory can be addressed directly at any time. It contrasts with sequential access media, as magnetic tape, that must be read partially in sequence regardless of the needed content.

There are three fundamental kinds of memory used in microprocessor systems - commonly termed as ROM, RAM, and hybrid. RAM and ROM are - "Random Access Memory" and "Read Only Memory". The program may be stored in ROM or RAM - this program does not normally change whereas it executes - whereas data is stored in the registers and RAM. Evidently, if you turn off the chip and turn this on again, you have lost all the contents of the registers, and Random Access Memory.

In typical computer, it possible is in RAM, to provide the maximum possible flexibility; you have fundamental programmes permitting you to interact with keyboards, discs and the display in ROM, and load in as much of the software as possible while you run the programs.

Posted Date: 5/25/2013 6:40:24 AM | Location : United States







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