Primary Memory (ROM and it‘s types – PROM, EPROM, EEPROM, RAM)

 

Primary Memory

Primary memory, also known as main memory, is directly accessible by the CPU and temporarily holds data and instructions needed for processing tasks. It is volatile memory, meaning its content is lost when the power is turned off.

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Types of Primary Memory

1. ROM (Read-Only Memory)

   • Function: Stores permanent data that cannot be modified easily.
   • Types of ROM:
     • PROM (Programmable Read-Only Memory)
       • Function: Can be programmed once by the user, but cannot be erased.
       • Uses: Used in early systems for storing firmware or static data.
     • EPROM (Erasable Programmable Read-Only Memory)
       • Function: Can be erased using ultraviolet light and reprogrammed multiple times.
       • Uses: Utilized in applications where software updates are required.
     • EEPROM (Electrically Erasable Programmable Read-Only Memory)
       • Function: Can be erased and rewritten electronically multiple times.
       • Uses: Used in devices where data must be frequently updated, such as in embedded systems.

2. RAM (Random Access Memory)

   • Function: Temporary memory used to store data actively being used or processed.
   • Uses: Stores data that changes frequently, such as the operating system, applications, and data in use.

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Differences Between ROM Types

Type	Erasability	Reusability	Applications
PROM	Once	No	Early firmware storage
EPROM	Erasable using UV	Reprogrammable	Software development and testing
EEPROM	Electrically	Reprogrammable	Embedded systems, microcontrollers, IoT devices

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RAM (Random Access Memory)

• Function: Volatile memory used for active data storage while the computer is running.

• Types:

  • SRAM (Static RAM): Faster, used in cache memory.
  • DRAM (Dynamic RAM): Slower, used as main memory.

• Uses: General-purpose memory used to store temporary data for computations, applications, and system processes.

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Characteristics of Primary Memory

• Volatile: Data is lost when power is turned off.
• Faster: Higher speed compared to secondary memory (e.g., hard drives or SSDs).
• Limited Capacity: Typically has lower storage capacity compared to secondary storage.

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Advantages of Primary Memory

• Fast data access speeds.
• Holds data actively used by the CPU.
• Essential for running applications efficiently.

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Summary: Primary memory is crucial for a computer’s functionality, serving as the bridge between the CPU and secondary storage, with different types tailored for specific needs like permanent data storage (ROM) and temporary data manipulation (RAM).