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Lecture 3 - Processors, Memory and I/O devices
- 1. Processors, Memory andI/O Devices Md. Imran Hossain Showrov (showrovsworld@gmail.com) 3 1
- 2. Outline Basic Processorand Memory Architecture Central Processing Unit Registers The Main Memory Secondary Storage Input / Output (I/O) devices Commonly used input devices Commonly used output devices
- 3. Basic Processor andMemory Architecture
- 4. Central Processing Unit(CPU) The Brain of the computer system. Performs all major calculations and comparisons Activates and controls the operations of other units of a computer system Two basic components are Control Unit (CU) Arithmetic Logic Unit (ALU)
- 5. Control Unit (CU) One of the basic components of CPU Acts as the central nervous system of a computer system Selects and interprets program instructions, and coordinates execution.
- 6. Arithmetic Logic Unit(ALU) One of the two basic components of CPU Actual execution of instructions takes place in ALU. Carry out all the arithmetic and logic operations.
- 7. Registers A Registeris a group of binary cells suitable for holding binary information. Registers are used to hold information on a temporary basis as the instructions are interpreted and executed by the CPU. Registers are part of the CPU of a computer. The length of a register, sometimes called its word size, equals the number of bits it can store.
- 8. The Main Memory Every computer has a temporary storage built into the computer hardware It stores instructions and data of a program mainly when the program is being executed by the CPU. This temporary storage is known as main memory, primary storage, or simply memory. Physically, it consists of some chips either on the motherboard or on a small circuit board attached to the motherboard of a computer It has random access property It is volatile.
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- 10. Memory Capacity Memorycapacity of a computer is equal to the number of bytes that can be stored in its primary storage. The units are as follows Kilobytes (KB) : 1024 bytes Megabytes (MB) : 1,048,576 bytes Gigabytes (GB): 1,073,741824 bytes
- 11. Random Access Memory(RAM) RAM is the physical hardware inside a computer that temporarily stores data, serving as the computer's "working" memory. The purpose of RAM is to provide quick read and write access to a storage device.
- 12. Read Only Memory(ROM) ROM a non-volatile memory chip Data stored in a ROM can only be read and used - they cannot be changed ROMs are mainly used to store programs and data, which do not change and are frequently used. For example, system boot program
- 13. Cache Memory Itis commonly used for minimizing the memory- processor speed mismatch. It is an extremely fast, small memory between CPU and main memory whose access time is closer to the processing speed of the CPU. It is used to temporarily store very active data and instructions during processing.
- 14. Limitations of PrimaryStorage Limited capacity because the cost per bit of storage is high. Volatile- data stored in it is lost when the electric power is turned off or interrupted.
- 15. Secondary Storage Alsoknown as auxiliary memory Used in a computer to overcome the limitations of primary storage Has virtually unlimited capacity because the cost per bit of storage is very low Slower than primary memory Large volume of data are stored on a permanent basis Example: Hard Disk, Floppy etc.
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- 17. How Information Getsin Your Computer? Do you ever wonder how information gets in your computer and how comes out in a form you can use? So, It is only possible with the help of Devices.
- 18. What is Device? It can be defined as the components or peripeharls which are attached to the computer to enter the data and get the desired result. Examples:- Monitor, Keyboard, Mouse, Printer etc.
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- 20. I/O Devices Providemeans of communication between a computer and outer world Also known as peripheral devices because they surround the CPU and memory of a computer system Input devices are used to enter data from the outside world into primary storage Output devices supply results of processing from primary storage to users
- 21. Roles of I/ODevices
- 22. Commonly Used InputDevices Keyboard Mouse Joystick. Light Pen Track Ball Scanner Digitizer Microphone
- 23. Commonly Used OutputDevices Monitor 3D Printer Braille reader GPS. Headphones Printers