Presented By:

Abdul Majid

Presentation on Computer Memory, bus interconnection ,

Operating System and

its function

Computer science

Index What is RAM and ROM Type of RAM and ROM What is Cache memory Bus interconnection What is operaing system Major function of operating system Type of operating system

MEMORY

RAM • RAM(Random Access Memory) is a

form of data storage that can be accessed randomly at any time, in any order or form any physical location, allowing quick access and manipulation.

• RAM allow the computer to read data quickly to run application. It allows reading and writing.

• RAM is volatile memory.• It expressed in kilobyte (KB) and

megabyte (MB)

ROM• ROM (Read Only Memory) is also

form of data storage that can be easily altered or reprogrammed. Stores instructions that are not necessary for re-booting up to make the computer operate when it is switched off.

• ROM stores the program to required initially boot the computer.it only allows reading.

• ROM is non- volatile.

Type of RAM

DRAM (DYNAMIC RAM) Stores each bit of data in a separate Capacitor in the form of electric charge. Chip is refreshed frequently. Accessible data in the form of 0s and 1s. It used old microcomputers. Its slow speed than SRAM. Less expensive.

Type of RAM

SRAM (STATIC RAM) Memory cell are made from digital gate. Gates store data. It is not refreshed frequently. About 10 time Faster than DRAM. Used modern computer. More expensive than DRAM.

Type of ROM

Programmable ROM Consists of blanks chip in which data and program stored. Burning process.

Type of ROM

Erasable programmable ROM (EPROM) It can be erased and reprogrammed repeatedly. The EPROM chip has a small window on top allowing it to be

erased by shining ultra-violet light on it. Much more useful than a regular PROM. It required erasing light. Access time is around 45 – 90 nanoseconds.

Type of ROM

Electrically erasable programmable ROM(EEPROM) it much easier to erase and reprogram. It can be erase under the software controlled. Access times between 45 and 200 nanoseconds.

What is cache memoryCache memory is fast memory that serves as a buffer between the processor and main memory. The cache hold data that recently used by the processor and saves a trip all the way back to slower main memory.Without cache memory, every time the CPU requests for data, it would send the request to the main memory which would then be sent back across the system bus to the CPU. This is a slow process.

Levels of Cache• Level 1(L1) Cache: This cache is inbuilt in the processor and is made of

SRAM(Static RAM). primary cache ranges in size from 8 to 64 KB. This type of Cache Memory is very fast because it runs at the speed of the processor.

• Level 2(L2) Cache: The L2 cache is larger but slower in speed than L1 cache. It is used to see recent accesses that is not picked by L1 cache and is usually 64 to 2 MB in size. A L2 cache is also found on the CPU or separate chip.

• Level 3(L3) Cache: L3 Cache memory is an enhanced form of memory present on the motherboard of the computer. It is an extra cache built into the motherboard between the processor and main

memory to speed up the processing operations and having more than 3 MB of storage in it.

Bus interconnection • For exchange of data between the computer system and

other devices through internal communication channel.What is bus: The collection of wires that are used to carry data from one

part of the computer to another. Wires consist of parallel metal lines and flexible ribbon cable. Each line in the bus can carry one bit of data at a time. A group of line is used to simultaneously carry multiple bits of

data. The number of lines used simultaneously to carry data called

bus width.

Type of busses

1. System bus connects the processor with the main memory and other devices.

2. Expansion bus allows the processor to communicates with the peripheral devices connected to the computer.

Component busses in the bus interconnection

1.Data bus• The line that are used to carry data between the microprocessor and the main

memory.• Data bus is bi-direction bus.• write and read operation.2. Address bus • A group of line to specify the source or destination of the data on the data bus.• Address bus is a unidirectional bus.3.Control bus• A separate group of line is used to select which component will use the data

and address busses at a particular time.• Control signal• Control signal consist of timing information and command signal.

Operating System and its Functions

What is Operating System

• operating system is the set of programs that controls a computer.

• It provide a pleasant and effective interface between the user and the hardware.

• Without it, computer can not run.• when the computer is on, OS will first load

into the main memory

Contd……..

Functions of Operating system

• Process Management• Managing hardware resource• Memory management• Allocation and assignment• Scheduling• Providing user interface

1.Process management

• By process management OS manages many kinds of activities :-All process from start to shut downCreation and deletion of user and system

processes.

2.Managing hardware resources

• OS manages the activities of the computer system.

• It keeps information about various system resources and devices.

• It allows the authorized user to log on the system

3. Memory Management

• The major activities of an operating regard to memory-management are:-Decide which process are loaded into memory

when memory space becomes available.Allocate and deallocate memory space as needed.

4.Allocation and assignment

• OS allocates computer resources to the programs.

• It assigns location in memory for data and instruction.

• It monitors the contents of the main memory and clear item from memory when they are no longer required by the CPU.

5.Scheduling

• A computer can run several programs simultaneously. The OS schedules these programs in various areas of the computer so that different parts of different programs can be worked on at same time.

6.Providing user interface

• A Providing user interface is an interface between system and the user. There are two types of user interface:-Command lineGraphical user interface

Contd……

• With a command line user interface the user interact with the OS by typing command to perform specific tasks

• With a graphical user interface the user interacts with the OS by using a mouse to access windows icons and menus

Different Types of Operating Systems

• iOS • Linux • OS X • QNX • Microsoft Windows• IBM z/OS • RedHat