introduction to computer

What is a computer? Electronic machine operating under the control of instructions stored in its own memory. – Accepts data – Manipulates data – Produces results – Stores results The term computer isderived from the Latin term ‘computare’, this means to calculate. Computer is an advanced electronic device that takes raw data as input from the user and processes these data under the control of set of instructions (called program) and gives the result (output) and saves output for the future use.

Components of Computer

five major computer operations 1) it accepts data or instructions by way of input, 2) it stores data, 3) it can process data as required by the user, 4) it gives results in the form of output, and 5) it controls all operations inside a computer.

Components of A computer Input Unit Output Unit Central Processing Unit (CPU) ALU(Arithmetic Logical Unit) & Control Unit(CU) Memory Unit Secondary Storage Unit

ALU Arithmetic operations: Logical operations: Increment Decrement Add Subtract Multiply Divide Logical operations: NOT AND OR XOR

Input Devices Key Board Pointing Devices - Mouse, Trackball, Touchpad, Pointing stick, joystick and a wheel, light pen, touch screen Voice Input Digital camera Video Input- Digital Video Camera Scanners and Reading devices(Barcode readers)

Output devices Monitors Printers Speakers and Headsets

Computer - Memory Computer memory is the storage space in computer where data to be processed and instructions required for processing are stored. Memory is primarily of three types: Cache Memory Primary Memory/Main Memory Secondary Memory

Primary Memory/Main Memory Main memory is divided into 2 parts Random Access Memory(RAM) Read Only Memory(ROM)

Primary Memory/Main Memory Random Access Memory(RAM) Volatile Read/Write by User Two Categories - DRAM (Dynamic RAM) requires regular refresh. - SRAM(Static RAM) faster & expensive than DRAM The more RAM a computer has, the faster it responds.

Primary Memory/Main Memory Read Only Memory(ROM) Non-Volatile Written by manufacturer Hold the booting program Categories: - ROM - PROM(Programmable ROM) - EPROM(Erasable PROM) - EEPROM (Electronically EPROM)

PROM : Short for programmable read-only memory, a memory chip on which data can be written only once. Once a program has been written onto a PROM, it remains there forever. Unlike RAM, PROMs retain their contents when the computer is turned off. The difference between a PROM and a ROM (read-only memory) is that a PROM is manufactured as blank memory, whereas a ROM is programmed during the manufacturing process. To write data onto a PROM chip, you need a special device called a PROM programmer or PROM burner. The process of programming a PROM is sometimes called burning the PROM. EPROM : Acronym for erasable programmable read-only memory, and pronounced ee-prom, EPROM is a special type of memory that retains its contents until it is exposed to ultraviolet light. The ultraviolet light clears its contents, making it possible to reprogram the memory. To write to and erase an EPROM, you need a special device called a PROM programmer or PROM burner.

EEPROM Short form of electrically erasable programmable read-only memory. EEPROM is a special type of PROM that can be erased by exposing it to an electrical charge. Like other types of PROM, EEPROM retains its contents even when the power is turned off.

Cache Memory Cache memory is faster than main memory, but slower than the CPU. Cache memory, which is normally small in size, is placed between the CPU and main memory

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Storage Devices(Secondary memory) Categories: Magnetic storage Optical storage Flash Drives

Optical Storage devices, Two main types of optical disks are : CD & DVD

Registers Fast stand-alone storage locations that hold data temporarily in CPU. Types of Register: PC (Program Counter) Keep address of the instruction currently being executed. Incremented after execution of the instruction. Instruction Register Store the instruction currently being executed Data Registers Hold data before it can be processed

I ←[PC] PC++ R1 ← A R2 ← B R3 ← R1 + R2 C ← R3 2000 CA+B 2004 CC-5 10 A 20 B 30 C 10 20 30 A most generic computer system is composed of a unit to do arithmetic, shift and logical micro-operations commonly know as ALU of CPU. General Purpose Registers: R1, R2, R3. As the name General Purpose Registers, suggests that the registers are involved in operations like load inputs, store intermediate results of arithmetic, logical and shift micro-operations. The initial inputs are loaded into registers from memory and final results are later moved into memory. Instruction Register IR and Decoder: After instruction is fetched from the memory its stored in Instruction Register. The instruction is then decode by the decoder. CA+B ADD 2000

Memory Hierarchy Speed Cost Space Secondary Memory

Hardware Component of Computer Systems Communication Devices Secondary Storage - Magnetic disk Central Processing Unit (CPU) Primary Storage Input Devices - Keyboard Output Devices - Printers Buses

System Bus Model A computer system consists of 3 major components (CPU, Memory, I/O) A shared pathway called system bus handles communication among those components.

System Bus Model… These buses consist of printed copper paths(copper wires). A single wire can handle bit a time. There are 3 types of busses. Data bus - Carry out data from microprocessor to memory during a write program. Address bus - Carries addresses generated by the microprocessor to the memory and to the I/O elements. Control bus - Carries timing and control signals to coordinate the activities of the entire system.

Computer - motherboard Motherboard varies greatly in supporting various types of components. Motherboard supports a single type of CPU and few types of memories. Video Cards, Hard disks, Sound Cards have to be compatible with motherboard to function properly. Motherboards, cases and power supplies must be compatible to work properly together.

Hard Drive Much like a floppy, the hard disk located inside the computer case is made of a stack of rotating disks, called platters. Data is recorded on a series of tracks that have been divided into sectors. Most computers have one hard drive, located inside the computer case. If a computer has one hard drive, it is called drive C. If a computer has additional hard drives, they are called drives D, E, and so on. A hard drive stores your programs. When you buy a new program, you must install the program files to your hard drive before you can use the program. A hard drive stores your data files such as documents spreadsheets, and graphics.

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