Computer Fundamental
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Primary Memory

Primary Memory

Primary memory is the main memory of computer. Primary storage, also known as main storage or memory, is the main area in a computer in which data is stored for quick access by the computer's processor. It is a chip mounted on the motherboard of computer.
Primary memory is categorized into two main types -
» Random Access Memory RAM)
» Read Only Memory (ROM)

Random Access Memory (RAM)

RAM is used for the temporary storage of input data, output data and intermediate results. The input data entered into the computer using the input device, is stored in RAM for processing. After processing, the output data is stored in RAM before being sent to the output device. Any intermediate results generated during the processing of program are also stored in RAM.
Depending on the technology used to construct a RAM are two types
1. Dynamic RAM (DRAM)
2. Static RAM (SRAM)

Read Only Memory (ROM)

ROM is a non-volatile primary memory. It does not lose its content when the power is switched off. Unlike RAM, the data once stored in ROM either cannot be changed or can only be changed using some special operations. Therefore, ROM is used to store the data that does not require a change. Flash memory is another form of rewritable read-only memory that is compact, portable, and requires little energy.
Depending on the programmed and re-programmed writing technique ROM are three types :
1. Programmable ROM (PROM)
2. Erasable Programmable ROM (EPROM)
3. Electrically Erasable Programmable ROM (EEPROM)

Characteristics of Main Memory

• These are semiconductor memories
• It is known as main memory
• Usually volatile memory
• Data is lost in case power is switched off
• It is working memory of the computer
• Faster than secondary memories
• A computer cannot run without primary memory