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12.1: Random Access Memory (RAM) and Read Only Memory (ROM)

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    Memory Basics

    Memory is the most essential element of a computing system because without it computer can’t perform simple tasks. Computer memory is of two basic type – Primary memory(RAM and ROM) and Secondary memory(hard drive,CD,etc.). Random Access Memory (RAM) is primary-volatile memory and Read Only Memory (ROM) is primary-non-volatile memory.


    RAM is made up of SRAM and DRAM. ROM is made up of PROM, EPROM and EEPROM memory
    Figure \(\PageIndex{1}\): ("Classification of Computer Memory" by Deepanshi_MittalGeeks for Geeks is licensed under CC BY-SA 4.0)
    1. Random Access Memory (RAM)
    • It is also called as read write memory or the main memory or the primary memory.
    • The programs and data that the CPU requires during execution of a program are stored in this memory.
    • It is a volatile memory as the data loses when the power is turned off.
    • RAM is further classified into two types- SRAM (Static Random Access Memory) and DRAM (Dynamic Random Access Memory).


    difference-1.pngThere are several differences between SRAM and DRAM - to many differences to enumerate here.
    Figure \(\PageIndex{1}\):    Difference between SRAM and DRAM. ("Difference between SRAM and DRAM" by Deepanshi_MittalGeeks for Geeks is licensed under CC BY-SA 4.0)
    1. Read Only Memory (ROM)
    • Stores crucial information essential to operate the system, like the program essential to boot the computer.
    • It is not volatile.
    • Always retains its data.
    • Used in embedded systems or where the programming needs no change.
    • Used in calculators and peripheral devices.
    • ROM is further classified into 4 types- ROMPROMEPROM, and EEPROM.

    Types of Read Only Memory (ROM) –

    1. PROM (Programmable read-only memory) – It can be programmed by user. Once programmed, the data and instructions in it cannot be changed.
    2. EPROM (Erasable Programmable read only memory) – It can be reprogrammed. To erase data from it, expose it to ultra violet light. To reprogram it, erase all the previous data.
    3. EEPROM (Electrically erasable programmable read only memory) – The data can be erased by applying electric field, no need of ultra violet light. We can erase only portions of the chip.


    There are several differences between RAM and ROM. RAM is temporary storage - ROM is permanent storage. RAM is volatile ROM is non-volatile. RAM is used for normal operations ROM is used for startup operations. Writing to RAM is faster than writing to ROM
    Figure \(\PageIndex{1}\):  ("Difference between RAM and ROM" by Deepanshi_MittalGeeks for Geeks is licensed under CC BY-SA 4.0)


    Adapted from:
    "Random Access Memory (RAM) and Read Only Memory (ROM)" by Deepanshi_MittalGeeks for Geeks is licensed under CC BY-SA 4.0

    This page titled 12.1: Random Access Memory (RAM) and Read Only Memory (ROM) is shared under a CC BY-SA license and was authored, remixed, and/or curated by Patrick McClanahan.

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