Computer Memory

Memory is major part of computers that categories into several types. Memory is best storage part to the computer users to save information, programs and etc, The computer memory offer several kinds of storage media some of them can store data temporarily and some them can store permanently. Memory consists of instructions and the data saved into computer through Central Processing Unit (CPU).

The performance of computer mainly based on memory and CPU. Memory is internal storage media of computer that has several names such as majorly categorized into two types, Main memory and Secondary memory.

1. Primary Memory / Volatile Memory:

Primary Memory also called as volatile memory because the memory can’t store the data permanently. Primary memory select any part of memory when user want to save the data in memory but that may not be store permanently on that location. It also has another name i.e. RAM.

Random Access Memory (RAM):

The primary storage is referred to as random access memory (RAM) due to the random selection of memory locations. It performs both read and write operations on memory. If power failures happened in systems during memory access then you will lose your data permanently. So, RAM is volatile memory. RAM categorized into following types.

DRAM
SRAM
DRDRAM

2. Secondary Memory / Non Volatile Memory:

Secondary memory is external and permanent memory that is useful to store the external storage media such as floppy disk, magnetic disks, magnetic tapes and etc cache devices. Secondary memory deals with following types of components.

Read Only Memory (ROM) :

ROM is permanent memory location that offer huge types of standards to save data. But it work with read only operation. No data lose happen whenever power failure occur during the ROM memory work in computers.

ROM memory has several models such names are following.

1. PROM: Programmable Read Only Memory (PROM) maintains large storage media but can’t offer the erase features in ROM. This type of RO maintains PROM chips to write data once and read many. The programs or instructions designed in PROM can’t be erased by other programs.

2. EPROM : Erasable Programmable Read Only Memory designed for recover the problems of PROM and ROM. Users can delete the data of EPROM thorough pass on ultraviolet light and it erases chip is reprogrammed.

3. EEPROM: Electrically Erasable Programmable Read Only Memory similar to the EPROM but it uses electrical beam for erase the data of ROM.

Cache Memory: Mina memory less than the access time of CPU so, the performance will decrease through less access time. Speed mismatch will decrease through maintain cache memory. Main memory can store huge amount of data but the cache memory normally kept small and low expensive cost. All types of external media like Magnetic disks, Magnetic drives and etc store in cache memory to provide quick access tools to the users.

Dual In-line Memory Module - DIMM

Dual In-line Memory Module, DIMM is a module containing a circuit board and one more random access memory chips.

DIMMs have a 168-pin connector and, since the advent of the Pentium Processor, a 64-bit path. Because of the new bit path, DIMMs can be installed one at a time, unlike SIMMs that would require installation in pairs.

SO-DIMM, which is short for Small Outline DIMM, is available in both a 72-pin and 144-pin configuration. SO-DIMMs are commonly utilized in laptop computers. Below is an example picture of a 4GB SODIMM memory stick from Crucial.

Advantages DIMMs have over SIMMs

DIMMs have separate contacts on each side of the board, which provides twice as much data as a single SIMM.
The command address and control signals are buffered on the DIMMs. With heavy memory requirements, this buffering reduces the loading effort of the memory.

Arithmetic Logic Unit (ALU)

It is one of the main components of the Central Processing Unit. This is where all arithmetic and logic operations are done. Data received from an input device is stored in primary memory before being passed on to ALU for processing.
Memory
Memory is the location where data and instructions are stores. They can be retrieved from memory whenever required. Memory is used to:
1. Hold the data received from input device temporarily and ready it for processing.
2. Hold data that has been processed and the intermediate results generated within.
3. Hold the finished results of processed data, until released to output devices.
4. Hold the system software and application software in use.

Data is stored in memory as bytes. A byte is made up of eight bits. A bit is the smallest unit of memory. Other units of memory are Kilobytes(KB), Megabytes(MB), Gigabytes(GB) and Terra bytes (TB) where:

1 KB = 1024 bytes
1 MB = 1024 KB = 1024 * 1024 bytes
1 GB = 1024 MB
1 TB = 1024 GB

Memory can be classified into two groups:
1. Main Memory
2. Secondary Memory

Main Memory
Every computer comes with a certain amount of physical memory, usually referred to as the main memory of RAM( Random Access Memory)
There are different kinds of main memory:
RAM (Read/write or R/W). this type of memory is also known as random access memory. This is volatile, which means, when the power is turned off, all the contents are destroyed. This memory is again of two types: Static RAM and Dynamic RAM.
ROM (Read Only Memory). The ROM is non-volatile, which means, it retains the stored information even if the power is turned off.
ROM is again of four types:
Masked ROM, PROM (Programmable ROM), EPROM( Erasable Programmable ROM) and EEPROM(Electrically Erasable Programmable ROM).
Secondary Memory:
Secondary Memory includes storage devices like cassette tape, magnetic tape, floppy disk, hard dist, Winchester disk, etc.

Memory Management

The new Operator
In order to request dynamic memory there is the operator new. This operator new is followed by a data type and optionally the number of elements required within brackets[]. IT returns a pointer to the beginning of the block assigned memory. Its form is:

pointer=new type                       or
pointer=new type[Number of Elements]

The first expression is used to assign memory that will hold one single element of a data type. the second one is used to assign LEARN MORE>>