Computer Hardware
Objectives • Explain why most computers are digital • Describe the role of the ALU • List factors that affect performance • Explain RAM • Compare storage technologies • Describe computer’s expansion bus • Explain hardware compatibility considerations • Compare and contrast technologies for peripherals M. Eyadat
Data Representation • Data representation makes it possible to convert letters, sounds, and images into electrical signals • Digital electronics makes it possible for computer to manipulate simple “on” and “off” signals to perform complex tasks • A digital device works with discrete data or digits, such as 1 and 0 • An analog device works with continuous data such as sound waves M. Eyadat
Data Representation • A computer uses a bit (binary digit) as the building block for more complex data representations • Unlike the decimal system, the binary number system (base 2) uses only two digits 0, and 1. • The following table lists some decimal numbers and their binary equivalent: M. Eyadat
Data Representation • Character data is composed of letters, symbols, and numerals that will not be used in arithmetic operations • ASCII (American Standard Code for Information Interchange) requires only 7 bits for each character • Extended ASCII uses eight bits for each character M. Eyadat
Data Representation • EBCDIC (Extended Binary-Coded Decimal Interchange Code) is an alternative 8-bit used by older IBM systems • Unicode uses 16 bits and provide codes for 65,000 characters – a bonus for representing alphabets of multiple languages M. Eyadat
Data Representation • Sounds and pictures must be transformed into a format the computer can understand • A computer must digitize colors, notes, and instrument sounds into 1s and 0s • A computer stores bits as electronic pulses that can travel over circuits and wires M. Eyadat
Data Representation • Computer files contain a file header • A file header contains the information on the code that was used to represent the file data • It is read by the computer but never appears on the screen M. Eyadat
Data Representation • A bit is one binary digit (b) 0 • A byte is 8 bits (B) 0010 0100 • Kilobit (Kb) is 1,024 bits • Kilobyte (KB) is 1, 024 bytes • Megabyte(MB) is 1,048,576 bytes • Kilo- means a 1000, • Mega- means million, • Giga -means billion, • Tera- means trillion, and • Exa- means quintillion M. Eyadat
Computer Chip • Most electronic components inside a computer are integrated circuits- thin slices of silicon crystal packed with microscopic circuit elements • wires • transistors • capacitors • Resistors • The motherboard houses all essential chips and provides connecting circuitry between them M. Eyadat
The Motherboard M. Eyadat
Microprocessor Basics • A microprocessor is an integrated circuit designed to process instructions • The CPU has two parts • ALU (arithmetic logic unit) • performs arithmetic operations • performs logical operations • uses registers to hold data being processed • The CPU’s control unitdirects and coordinates processing. M. Eyadat
Microprocessor Basics • The microprocessor executes instructions provided by a computer program • The list of instructions that a microprocessor can perform is called its instruction set • CPU speed is influenced by several factors: • clock speed – Megahertz, Gigahertz • word size • Cache – Level 1, Level 2 caches • instruction set size • popular microprocessors • Intel • AMD (Advanced Micro Devices) • Motorola M. Eyadat
Microprocessor Basics • Computers based on a CPU with a complex instruction set known as CISC (complex instruction set computer) microprocessor • Intel • A RISC (reduced instruction set computer) has limited set of instructions that it can perform quickly • AMD M. Eyadat
Microprocessor Basics • Computers with a single processor execute instructions serially (one at a time) • Pipelining - technology in which the processor can begin executing next the instruction before it completes the previous instruction • A computer with more than one processor can execute multiple instructions simultaneously, referred to as parallel processing • Supercomputers M. Eyadat
