Computer Hardware

7/23/2016M. Eyadat2 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

7/23/2016M. Eyadat3 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

7/23/2016M. Eyadat4 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:

7/23/2016M. Eyadat5 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

7/23/2016M. Eyadat6 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

7/23/2016M. Eyadat7 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

7/23/2016M. Eyadat8 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

7/23/2016M. Eyadat9 Data Representation A bit is one binary digit (b)  0 A byte is 8 bits (B)  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

7/23/2016M. Eyadat10 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

7/23/2016M. Eyadat11 The Motherboard

7/23/2016M. Eyadat12 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 unit directs and coordinates processing.

7/23/2016M. Eyadat13 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

7/23/2016M. Eyadat14 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

7/23/2016M. Eyadat15 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