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Difference between Random Access Memory (RAM) and Hard Disk Drive (HDD)

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A person novice to computers often is in confusion between Random Access Memory (RAM) and Hard Disk Drive (HDD). Here we draw comparisons between the two. Similarities between RAM and HDD : 

  • Both are used for storage of data.
  • Both are physical components of the computer machine.
  • Both RAM and HDD are measured in bytes
  • Both RAM and HDD can affect the performance of a computer
  • Both RAM and HDD can be upgraded

Differences between RAM and HDD :

S. No.ParameterRAMHDD
1.Full FormRAM stands for Random Access Memory.HDD stands for Hard Disk Drive.
2.Also known asRAM is also known as primary memory.HDD is also known as secondary memory.
3.Type of storageThe data is temporarily stored in this type of memory.The data is permanently stored in this type of memory.
4.ComponentsRAM does not contains, mechanical parts, only electronical parts like transistors.HDD contains moving mechanical parts, like the arm.
5.R/W TimeRAM has shorter R/W time.HDD has longer R/W time.
6.VolatileRAM is a volatile memory. That implies a constant power supply is required for maintaining the contents of the memory.HDD is a non-volatile memory. That implies a constant power supply is not required for maintaining the contents of the memory cell.
7.Memory AccessIn RAM each and every element takes same time to be accessed.In HDD different elements take different time to be accessed.
8.SizeIn a system the RAM is smaller than the HDD.In a system the HDD is larger than the RAM.
9.CostRAM is costlier per unit storage.HDD is cheaper per unit storage.
10.NoiseRAM does not produces noise.HDD can produce noise due to mechanical movements.
11.Duration of DataData stored in RAM is temporary. It remembers as long as it has electricity, i.e. the power is on.Data stored in HDD is permanent, i.e. it retains data even after shutdown.
12.Speed of ComputerInadequate RAM slows down the speed of the computer.HDD does not affect the speed of the computer.

There are two form factors of RAM-

  • For Desktops and Servers- DIMM (Dual In-line Memory Module)
  • For Laptops- SO-DIMM (Small Outline DIMM)

There are two form factors of HDD-

  • For Desktop Computers- 3.5 inch 
  • For Laptops- 2.5 inch 
14.UsageTo increase the speed of the computer.To increase the space for storing data or contents of the computer.
15.Clearing of memoryAfter running of particular program or application, the memory is cleared.The memory is not cleared while in use or even after use by an application or program.
16.SpeedThe speed of accessing data is faster than HDD.The speed of accessing data in HDD is slower as compared to RAM.
17.Example of existence in different forms
  • Static RAM (SRAM)
  • Dynamic RAM (DRAM)
  • Hard disk (magnetic)
  • Floppy disk (magnetic)
  • Tape drive (magnetic)
  • CD-ROM or DVD-ROM (optical)
Last Updated : 12 May, 2023
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