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Chapter 4: Memory system

In this post I’m going to explain the memory-system architecture ,which is apart of my assignment  So after a few hours of research and arranged I can finally come to a few idea that can finish my post.


so WHAT IS MEMORY?
A computer's system memory refers to the part of a computer where instructions and the data that explain those instructions are stored. The more advanced memory capabilities a computer has, the faster and more efficiently it will be able to execute common tasks, together with the computer processor.

Components

  • A computer's memory system is made up of three major parts.
  • The first is the hard drive, which stores data, including all types of files and programs, long term. 
  • The second is RAM (random access memory) is a platform where the computer can work with frequently used or active data for short-term needs, speeding up performance.
  •  The third is the memory cache, which is part of the computer processor, and which is RAM memory that the computer reads first before reading from the larger memory system.
CHARACTERISTIC of computer memory system
  •   Location
  •   Capacity
  •  Unit of transfer
  •  Access method
  •  Performance
  •  Physical type
  •  Physical characteristics
  • Organisation

Memory Hierarchy




1.Decreasing cost per bit
2.Increasing capacity

3.Increasing access time

4.Decreasing frequency of access of the memory by the processor








RAM
Modern computers have Dynamic RAM, or DRAM, in which the memory is stored digitally inside a circuit board of cells. DRAM needs to be periodically refreshed with an electric charge to retain the information. When the computer is turned off, the DRAM data are no longer available.

ROM
Its a permanent storage which is non-volatile,random access but cannot be written.The contents of it cannot be overwritten under normal PC operations.The potential applications of ROM is library subroutines for frequently wanted functions,system program,function tables. There is a few types of ROM:
  • PROM-This type of ROM can be re-programmed by using a special device called a PROM programmer. Generally, a PROM can only be changed/updated once.

  • EPROM-This type of ROM can have its contents erased by ultraviolet light and then reprogrammed by an RPROM programmer. This procedure can be carried out many times; however, the constant erasing and rewriting will eventually render the chip useless.

  • EEROM-This type of ROM works in a similar way to Flash memory in that it can its contents can be 'flashed' for erasure ad then written to without having to remove the chip from its environment. EEPROMs are used to store a computer system's BIOS, and can be updated without returning the unit to the factory. In many cases, BIOS updates can be carried out by computer users wishing a BIOS update.



CACHE
-Small amount of fast memory
-Intermediate buffer between normal main memory and CPU
-May be located on CPU chip or module

CACHE DESIGN


Here is the video of  Memory Hierarchy : CacheMemory


Explanation of cache design(link)





Evolution of memory




Friday 26 April 2013 04:12 / 0 commentator(s) | Just click and you'll see. | Scroll up to top