A concise page title for "Memory" could be: *"Memory: The Mind's Archive"*.

*Memory in a PC: An Overview*

Memory in a PC, often referred to as RAM (Random Access Memory), is a crucial component that temporarily stores data and instructions for quick access by the CPU. Unlike permanent storage, such as a hard drive or SSD, RAM is volatile, meaning it loses its data when the PC is powered off. The more RAM a PC has, the more data it can handle simultaneously, leading to smoother multitasking and faster performance. RAM plays a pivotal role in the overall speed and efficiency of a computer, influencing how quickly applications load and how well the system handles complex tasks.

1. Duration: 50 min IV Semester 1/10/2024 1 Computer Organization & Types Computer organization - central processing unit- general structure, ALU, Registers, Control Unit, computer memory – primary memory and secondary memory. Secondary storage devices – Magnetic and optical media. Input and output units, operating system.

2. Unit - 2 Central Processing Unit (CPU) 2 1/10/2024 CPU

3. Unit - 2 Central Processing Unit (CPU) AGP - Accelerated Graphics Port PCI - Peripheral Component Interconnect SATA - Serial Advanced Technology Attachment SSD – Solid State Drive IDE – Integrated Drive Electronics 3 1/10/2024 CPU

4. Unit - 2 ALU An arithmetic logic unit (ALU) is a key component of a computer’s central processor unit. The ALU performs all arithmetic and logic operations that must be performed on instruction words. The ALU is split into two parts in some microprocessor architectures: the AU and the LU. Arithmetic operation subtraction, addition, division and multiplication Logical Operation (OR, AND, XOR, XAND and NOR, NOT operations). Binary Addition 4 1/10/2024 Computer Organization

5. Unit - 2 ALU Arithmetic operation subtraction, addition, division and multiplication Logical Operation (OR, AND, NOR, NAND and XOR, XNOR operations). 5 1/10/2024 Computer Organization

6. Unit - 2 ALU Addition of Two numbers using gates 6 1/10/2024 Computer Organization

7. Unit - 2 Computer memory 7 1/10/2024 Computer Organization

8. Unit - 2 Computer memory 8 1/10/2024 Computer Organization

9. Unit - 2 How Computer memory Work 9 1/10/2024 Computer Organization A program is loaded from secondary memory to primary memory when it is opened . Data in memory is only saved temporarily since memory is volatile A file is transported to secondary memory for permanently storage when it is saved. Integrated circuits utilizing metal- oxide- semiconductor (MOS) transistors based on silicon will be used to make semiconductor memory.

10. Unit - 2 How Computer memory Work 10 1/10/2024 Computer Organization

11. Unit - 2 Types of memory - RAM 11 1/10/2024 Computer Organization Cache memory. This temporary storage area, known as a cache, . It is also called CPU memory integrated directly into the CPU chip or a bus interconnect with the CPU. RAM. any storage location can be accessed directly by the processor. Static RAM. SRAM retains data bits in its memory for as long as power is supplied to it ., SRAM does not have to be periodically refreshed Dynamic RAM. DRAM is a type of semiconductor memory that is typically used by the data or program code needed by a computer processor to function . Unlike DRAM, which stores bits in cells consisting of a capacitor and a transistor . Single Data Rate Synchronous Dynamic RAM (SDR SDRAM) - Single Data Rate Synchronous Dynamic RAM (SDR SDRAM) is a type of RAM that can accept only one command (only in rising) and can transfer one word of data per clock cycle (0- 1 or 1-0)

12. Unit - 2 Types of memory - RAM 12 1/10/2024 Computer Organization Double Data Rate Synchronous Dynamic RAM.(DDR SDRAM) - DDR SRAM is SDRAM that can theoretically improve memory clock speed to at least 200 MHz. DDR4 RAM is a type of DRAM that has a high- bandwidth interface and is the successor to its previous DDR2 and DDR3 versions. DDR4 RAM allows for lower voltage requirements and higher module density. It is coupled with higher data rate transfer speeds and allows for dual in- line memory modules (DIMMS) up to 64 GB. Rambus Dynamic RAM (DRDRAM) is a memory subsystem that promised to transfer up to 1.6 billion bytes per second. The subsystem consists of RAM, the RAM controller, the bus that connects RAM to the microprocessor and devices in the computer that use it. Graphics Double Data Rate Synchronous Dynamic RAM (GDDR SDRAM) - 2003 to present transfer rate of 10 to 14 Gbit/s per pin

13. Unit - 2 Types of memory - ROM 13 1/10/2024 Computer Organization Read- only memory. ROM is a type of computer storage containing nonvolatile, permanent data that, normally, can only be read and not written to. ROM contains the programming that enables a computer to start up or regenerate each time it is turned on. Features of Read Only Memory It is non- volatile in nature. Less costly than the RAM. As, only read operation is allowed therefore, no changes can occur. It is easy to test the ROM. Due to its nature, it is more reliable than RAM. Does not require any refreshing.

14. Unit - 2 Types of memory - ROM 14 1/10/2024 Computer Organization Programmable ROM. PROM is ROM that can be modified once by a user. It enables a user to tailor a microcode program using a special machine called a PROM programmer . Erasable PROM. EPROM is programmable read- only memory PROM that can be erased and re- used. Erasure is caused by shining an intense ultraviolet light through a window designed into the memory chip. Electrically erasable PROM. EEPROM is a user- modifiable ROM that can be erased and reprogrammed repeatedly through the application of higher than normal electrical voltage. Unlike EPROM chips, EEPROMs do not need to be removed from the computer to be modified. However, an EEPROM chip must be erased and reprogrammed in its entirety, not selectively.

15. Unit - 2 Difference between RAM & ROM RAM It is temporary storage. Storage capacity is in MBs. It is volatile in nature. Stores the data and information of the programs and applications currently on the system. We can access and change the data. Speed is high. It is expensive. RAM is used as the cache or primary memory. Its types are SRAM and DRAM. 15 1/10/2024 Computer Organization ROM It is permanent storage. Storage capacity is in GBs. It is non- volatile in nature. On the other hand, it stores programs during the startup of the system. We can only read the data. Speed is much less in comparison to RAM. It is less expensive than RAM. The firmware uses it as microcontrollers. Its types are PROM, EPROM, and EEPROM.

16. Unit - 2 Secondary Memory 16 1/10/2024 Computer Organization

17. Unit - 2 Secondary Memory Secondary storage, sometimes termed auxiliary storage, refers to the storage of data that is not accessed frequently as the data in primary storage. It is a non- volatile memory medium that preserves data until and unless it has been deleted or overwritten. Magnetic storage devices use magnetization process to write, rewrite and access data. Data gets saved here in binary form. These devices store data in the form of tiny, magnetized dots. The dots are created, read and erased using magnetic fields created by tiny electromagnets Hard disk drives (HDDs): They consist of a series of circular disks called platters, arranged one over the other around a spindle. The disks are made of non- magnetic materials and coated with magnetic material. A typical modern HDD has a storage capacity measured in terabytes (TB). 17 1/10/2024 Computer Organization

18. Unit - 2 Secondary Memory Tape drives Devices that store data on magnetic tape are known as tape drives. These devices allow large volumes of data to be mechanically created, stored for a long time and easily accessed. Floppy disk drives This flexible disk has a magnetic coating on it and is packed inside a protective plastic envelope. One of the oldest portable storage devices, floppy disks are not used that much now due to their limited storage capacity. Optical storage devices These devices use optical storage technology to read and write data. Data gets stored digitally, and lasers are used in these devices to read and write data. CD drives CD drives generally use laser rays to read and write data. With 700 MB of storage space, these devices are cheap, portable and one of the most popular storage devices used. 18 1/10/2024 Computer Organization

19. Unit - 2 Secondary Memory DVD drives They can store 15 times the data CDs hold and rich multimedia files that require high storage capacity. Blue- ray drives A blue- ray disk can store high-definition (HD) video and other multimedia files. It uses a shorter wavelength laser than CD/DVD and therefore can store more data. Solid- state storage devices Solid- state storage devices do not involve magnetic disks or any moving parts. They store data on non- moving components. Solid- state drives (SSDs) These devices store data using flash- based memory much faster than traditional hard disks. SSDs have no moving parts and upgrading to one is a great way to speed up your computer and make it more resilient. USB drives USB flash drives are essential for quickly moving files from one system to another. They can now hold up to 2TB of storage and are a convenient medium to store and transfer smaller files. 19 1/10/2024 Computer Organization

20. Unit - 2 I / O Units 20 1/10/2024 Computer Organization

21. Unit - 2 Various Operating Systems 21 1/10/2024 Computer Organization

22. Unit - 2 Operating System Operating Systems The operating system is the most important program that runs on a computer. An operating system is a computer program that handles the computer hardware . An operating system is a program that controls the execution of application programs and acts as an interface between the user of a computer and the computer hardware. It is responsible for the management and coordination of activities and the sharing of the resources of the computer. 22 1/10/2024 Operating System

23. Unit - 2 Operating System What Operating Systems is doing in your computer Recognizing input from the keyboard or mouse Sending output to the monitor Controlling peripheral devices such as disk drives and printers. Keeping track of files and directories on the disk 23 1/10/2024 Operating System

24. Unit - 2 24 OS - Introduction 1/10/2024 Functions of Operating System Security Control over System Performance Job Accounting Error Detecting Aids Coordination Between Other Software and Users Memory Management Processor Management/Scheduling Device Management File Management

25. Objectives and Functions of OS 25 OS - Introduction 1/10/2024 Functions of Operating System Security - The operating system helps in keeping the user data safe with help of protection like passwords and some other similar methods Control over System Performance - It also keeps a record of the response time between when the user has requested the service till the system responds back to have a complete overview of the system's health. Job Accounting- The operating system keeps a track record of the time and resources consumed by various tasks and users. Error Detecting Aids - The operating system is the one that is in charge of the detection of any error or bugs that can happen while performing any task. Unit - 2

26. Objectives and Functions of OS 26 OS - Introduction 1/10/2024 Functions of Operating System Coordination Between Other Software and Users - Operating systems also connect and assign interpreters, editors, compilers, and other software to a variety of computer programming users. Memory Management- It Manages Basic Memory or Primary Memory. It keeps track of basic memory, like, as which bytes of memory are being used by which user program. The memory addresses that are being used and being unallocated. In multiprogramming, the operating system is the one that decides the chronology for granting memory to the process. It provides the memory for a process when the process demands that and afterwards deallocates the memory when the process is completed or the process is terminated. Unit - 2

27. Objectives and Functions of OS 27 OS - Introduction 1/10/2024 Functions of Operating System Processor Management/Scheduling - The operating system performs a function called process scheduling, in which the OS decides the order in which different processes will have access to the processor, and how much power each process will have. First Come First Serve (FCFS) Round Robin Scheduling Shortest Job First (SJF) Priority- based scheduling etc. Device Management - There are three major techniques that are used for managing and allocating devices: Dedicated - It is a technique in which the device is assigned to a single task at a time. Shared - It is a technique in which the device is assigned multiple tasks at a time. Virtual - It is a technique in which one physical device is simulated on another physical device. File Management - A file management system is an organised collection of data into directories so that it can be easily navigated and used. These may contain other directories and files as well. Unit - 2

28. OS - Logos 1/10/2024 48 Unit - 2 Windows logo milestone

29. OS - Evolution 1/10/2024 49 Unit - 2 Evolution of OS Evolution of OS Four generations of operating systems. The First Generation (1945 – 1955) The Second Generation (1955 – 1965) The Third Generation (1965 – 1980) The Fourth Generation (1980 – till date)