Computer Memory

You all must have heard computer related terms like RAM, ROM, and Hard disks in your day-to-day life. Do you know what that really is? Where do the computers store their information or the data? Where does all the data transferred to the computers go? Well, computer memory is the most essential part of computers as without it computers cannot perform any functions. Memory is the storage where the computers store all their data and information. Computer memory is a generic term which includes all types of data storage used by a computer to store information and data. Computer memory is basically of 2 types: Primary Memory and Secondary Memory.

Some of the memory is designed to be very fast which enables the CPU to access the data stored very quickly and some of the memory is designed to be low cost which enables the user to store large amounts of data.

Units to Measure Memory

The units to measure the memory are as follows:

• Bit = 0 or 1 (Binary digit)

• Nibble = 4 bits

• 1 byte (b) =  8 bits

• 1 Kilobyte (KB) = 1024 B

• 1 Megabyte (MB) = 1024 KB

• 1 Gigabyte (GB) = 1024 MB

• 1 Terabyte (TB) = 1024 GB

• 1 Petabyte (PB) = 1024 TB       

Primary Memory

Primary Memory is the memory which enables the computers or the CPU to store the data that the CPU needs immediately so that it does not have to wait for it. Primary Memory holds the data and the instructions on which the computer is currently working on.  

Characteristics of Primary Memory

Some of the important characteristics of Primary Memory are listed below:

• Primary memory is faster than the secondary memory. 

• Computers cannot run without primary memory.

• Primary memory is also usually called volatile memory.

• It loses its data when the power is turned off. 

Types of Primary Memory: 

• Random Access Memory (RAM)

• Read Only Memory (ROM)

1. Random Access Memory (RAM)

RAMs are made up of a series of chipset that allow only for temporary data storage. RAM is the holding zone to open the files and the critical information that might be required immediately while working. RAM can be viewed as the “placeholder” for valuable information while working and is not the storage of the computer. RAM gets cleared once the power is turned off.

Data which is required for immediate processing is only moved to RAM where it can be easily accessed and modified very quickly without making the computer wait.

RAM are basically of 2 types:

• DRAM

• SRAM

DRAM 

DRAM stands for Dynamic Random Access Memory. DRAM is the most commonly found RAM in computers. 

SRAM

SRAM stands for Static Random Access Memory. SRAM is comparatively faster than DRAM but is more bulky and costly also. SRAMs are mostly used in very high end server systems.

RAM Stick

2. Read Only Memory (ROM)

As the name suggests, it is the type of memory in which we can only read the data stored but can not write the data. ROM is a type of non-volatile memory which eventually means that the data stored in the ROM does not get lost when the power is turned off.

The ROM usually contains the “bootstrap code” which is the basic set of instructions that a computer needs to carry out to become aware of the operating system that is stored in the secondary memory which makes the computer ready to use.

ROM are basically of 3 types: 

• PROM

• EPROM

• EEPROM

1. PROM

PROM stands for Programmable Read Only Memory. PROM is manufactured in an empty state but later, it is programmed using the PROM burner.

2. EPROM

EPROM stands for Erasable Programmable Read Only Memory. In EPROM, the data can be erased from it by removing it from the computers and exposing it to ultraviolet light. It later can be burned using the EPROM burner.

3. EEPROM

EEPROM stands for Electronically Erasable Programmable Read Only Memory. In EEPROM, it can be erased and programmed by using the computer system itself. It is not strictly read only.

ROM

Secondary Memory

Secondary memory are the different types of storage media which can be directly attached to the computer systems. These memories are used to store data for long periods of time. These memories can also be used to transfer the data. Computers are unable to directly access these memories but instead they can be accessed by the input-output routines. The data in the secondary memory is first transferred to the main memory which enables the CPU to access it.

Characteristics of Secondary Memory

• These are also known as the backup memory. 

• The secondary memory is slower than the primary memory. 

• These are the non volatile memory which do not lose their data on power off. 

• They  store the data for a long period.

Different Types of Secondary Memory are as Follows:

• Hard Disk Drives (HDD): HDD is the storage device that stays inside the computer which has a spinning disk inside, in which the data is stored magnetically.

Hard Disk

• Solid State Drives (SSD): SSDs are the storage devices that are built using integrated circuits to store the data. These are faster than the HDDs.

SSD

• Optical Drives: Optical disk drives are the storage devices that use laser light or electromagnetic waves as a part of reading or writing the data to the disks.

Optical Disk Drive

Points to Remember 

• Primary Memory is essential for computers to run.

• SRAMs are faster than DRAMs.

• RAM, or random access memory, is a type of data storage device that allows for a quick read and write access.

• Secondary storage helps in storing data and information for a long period of time.

• ROMs are non-volatile in nature.

• DRAMs are used in normal computers and SRAMs are used in high-end server systems.

Learning by Doing

1. What are the key differences between primary memory and secondary memory?

2. SSDs are slower than the HDDs. (true/false)

Sample Questions

1. Choose the correct statement.

1. DRAM can be used to store information.

2. PROM can be formatted.

3. Computers cannot run without secondary memory.

4. SRAMs are faster than DRAMs.

Ans: D

2. Expand EEPROM.

Ans: Electronically Erasable Programmable Read Only Memory

3. What is the function of ROM?

Ans: The ROM contains the “bootstrap code” which is the basic set of instructions that a computer needs to carry out to become aware of the operating system that is stored in the secondary memory which makes the computer ready to use.

4. List various types of ROM.

Ans:  The various types of ROM are listed below:

1. PROM

2. EPROM

3. EEPROM

Summary 

In this article, we learnt about computer memory and its types. We also learnt about the units to measure memory. We have discussed primary and secondary memory and their characteristics. We learnt about which secondary memory is fast and which is comparatively slow also. We also learnt about the volatility of computer memory.