Random Access Memory - Computer Fundamentals

What is Random Access Memory?

RAM (Random Access Memory) is called as the internal memory of the CPU for storing data, program, and program result. It is called as read/write memory which stores the data until the machine is working. The data is erased as soon as the machine is switched off. Hence, it is called temporary storage memory.

RAM considers the access time independent of the address; the memory location stored inside the memory is as easy as to reach other locations. It takes the same amount of time to reach other locations. RAM data can be accessed randomly and is very expensive.

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RAM is said as volatile, i.e. the stored data stored in the memory get lost when the computer is switched off, or any power failure happens. Hence, a backup Uninterruptible Power System (UPS) is often used with computers. RAM is considered as small memory, both in terms of its physical size and the amount of data that it can store.

RAM is of two types −

  • Static RAM (SRAM)
  • Dynamic RAM (DRAM)

Static RAM (SRAM)

The word static means the memory retains its contents until the power is supplied. However, data will be lost once the power gets down due to its volatile nature. SRAM chips use a matrix of 6-transistors and no capacitors. Transistors do not require any power to prevent leakage, so SRAM need not be refreshed again and again on a regular basis.

There is an extra space in the matrix, hence SRAM uses more chips than DRAM for the same amount of storage capacity. It results in high manufacturing costs. SRAM is thus used as cache memory and has very fast access.

Characteristic of Static RAM

  • Long life
  • No need to refresh
  • Faster
  • Used as cache memory
  • Large size
  • Expensive
  • High power consumption

Dynamic RAM (DRAM)

DRAM, unlike SRAM, must be continually refreshed in order to maintain the data. This is done by keeping the memory on a refresh circuit so that it rewrites the data several hundred times per second. Due to low cost and small in size DRAM uses its system memory. All DRAMs are made up of memory cells, which consist of one capacitor and one transistor. Hence it is also called Random Access Memory.

Characteristics of Dynamic RAM

  • Short data lifetime
  • Needs to be refreshed continuously
  • Very slow as compared to SRAM
  • Used as RAM
  • Smaller in size
  • Less expensive
  • Less power consumption

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