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Memory Organization

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Masum Rehman

The document provides a history of computer memory technologies, beginning with delay line memory developed in the 1940s. Random access memory technologies then emerged in the late 1940s, including magnetic core memory which allowed memory retention after power loss. Magnetic core memory became the standard through the 1960s until being replaced by semiconductor memory. The document also defines different types of computer memory including primary memory (RAM, cache), secondary memory (hard disks), tertiary memory (CDs, DVDs), and offline memory (removable storage). It describes the roles of RAM and ROM in memory and defines cache memory as faster memory used to store frequently accessed data and instructions.

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PRESENTATION BY Abdullah Al Imran ID:142-15-3690 COMPUTER MEMORY
HISTORY OF MEMORY
DELAY LINE MEMORY o Developed by J. Presper Eckert in the early 1940s. o It is also used in digital computers. o Delay line memory would be limited to a capacity of up to a few hundred thousand bits to remain efficient. 3
RANDOM ACCESS COMPUTER MEMORY o The Williams tube and Selectron tube originated in 1946. o In 1947 Jay Forrester, Jan A. Rajchman and An Wang developed magnetic core memory which allowed for recall of memory after power loss. o The Selectron was limited to 256 bits, while the Williams tube could store thousands 4
MAGNETIC CORE MEMORY It was the computer memory of choice throughout the 1960s, until it was replaced by semiconductor memory. 5
Overview 6 Primary - storage of intermediate data - necessary to run the computer - RAM, Cache Secondary - long-term storage of data - HDD Tertiary - CD, DVD, memory card... Off-line - disconnected storage - unplugged USB flash drive - external HDD
MEMORY o It holds the data and instructions that the Central Processing Unit (CPU) needs. o It allows the CPU to direct interact with the program. o Memory is a need of every computer o Main memory is divided into two parts : - Random Access memory ( RAM ) should be better known as Read Write Memory - Read Only Memory (ROM) 7
8 Random Access Memory (RAM) Structure : A set of memory chips, each of them is an integrated circuit (IC) made of millions of transistors and capacitors Volatile - their state is lost or reset when power is removed from the system. Usage : Holds data/application programs from input devices or storages Bus : processing speed Types: --DRAM --SRAM
9 Read only memory (ROM) Has contents which are fixed when the chip is manufactured Holds the bootstrap loader part of the operating system Retains its data when the computer is switched off Types of ROM --PROM --EROM --EEROM
10 Cache memory Faster and expensive than RAM It improves the computers performance Processor can use it to store frequently accessed data and program instructions It is two types : - L1 : primary cache (inside the processor) - L2 : secondary cache (in the motherboard or near the microprocessor)
THANKS! Any questions? 11

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Memory Organization

  • 1. PRESENTATION BY Abdullah Al Imran ID:142-15-3690 COMPUTER MEMORY
  • 3. DELAY LINE MEMORY o Developed by J. Presper Eckert in the early 1940s. o It is also used in digital computers. o Delay line memory would be limited to a capacity of up to a few hundred thousand bits to remain efficient. 3
  • 4. RANDOM ACCESS COMPUTER MEMORY o The Williams tube and Selectron tube originated in 1946. o In 1947 Jay Forrester, Jan A. Rajchman and An Wang developed magnetic core memory which allowed for recall of memory after power loss. o The Selectron was limited to 256 bits, while the Williams tube could store thousands 4
  • 5. MAGNETIC CORE MEMORY It was the computer memory of choice throughout the 1960s, until it was replaced by semiconductor memory. 5
  • 6. Overview 6 Primary - storage of intermediate data - necessary to run the computer - RAM, Cache Secondary - long-term storage of data - HDD Tertiary - CD, DVD, memory card... Off-line - disconnected storage - unplugged USB flash drive - external HDD
  • 7. MEMORY o It holds the data and instructions that the Central Processing Unit (CPU) needs. o It allows the CPU to direct interact with the program. o Memory is a need of every computer o Main memory is divided into two parts : - Random Access memory ( RAM ) should be better known as Read Write Memory - Read Only Memory (ROM) 7
  • 8. 8 Random Access Memory (RAM) Structure : A set of memory chips, each of them is an integrated circuit (IC) made of millions of transistors and capacitors Volatile - their state is lost or reset when power is removed from the system. Usage : Holds data/application programs from input devices or storages Bus : processing speed Types: --DRAM --SRAM
  • 9. 9 Read only memory (ROM) Has contents which are fixed when the chip is manufactured Holds the bootstrap loader part of the operating system Retains its data when the computer is switched off Types of ROM --PROM --EROM --EEROM
  • 10. 10 Cache memory Faster and expensive than RAM It improves the computers performance Processor can use it to store frequently accessed data and program instructions It is two types : - L1 : primary cache (inside the processor) - L2 : secondary cache (in the motherboard or near the microprocessor)