Components of Hardware CPU Primary Storage Secondary Storage Communications Devices Output Devices Input Devices Buses
Number Systems Humans represent numbers in Base10 1 x 10 3 = 1,000 9 x 10 2 = 900 9 x 10 1 = 90 7 x 10 0 = 7 Decimal Value: Numeric Expression: Digits: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 10 0 10 3 10 2 10 1 7 9 9 1
Computers use Base2 (0, 1) 1 0 1 1 1 0 1 Decimal Value: Numeric Expression: Base2: 1011101 = Base10: 1 x 2 6 0 x 2 5 1 x 2 4 1 x 2 3 1 x 2 2 0 x 2 1 1 x 2 0 64 0 16 8 4 0 1 = 93 2 0 2 6 2 5 2 4 2 3 2 2 2 1 64 32 16 8 4 2 1
Character representation ASCII: American Standard Code for Information Interchange (ASCII-8) Formula: 128 + 32 + Position in Alphabet 10100001: ‘A’ 10100010: ‘B’ 10100011: ‘C’ 10100100: ‘D’ 10100101: ‘E’ 01010000: ‘0’ 01010001: ‘1’ 01010010: ‘2’ 01010011: ‘3’ 01010111: __
Size of data storage
Bit: 1 or 0
Byte: 8 bits (equals 1 character)
Kilobyte: 1,000 bytes (exactly 1024)
Megabyte: 1,000,000 bytes
Gigabyte: 1,000,000,000 bytes
Terabyte: 1,000,000,000,000 bytes
Measurements of Time
Millisecond: 1/1,000 second
Microsecond: 1/1,000,000 second
Nanosecond: 1/1,000,000,000 second
Picosecond: 1/1,000,000,000,000 second
Microprocessor: Very large-scale integrated circuit technology that integrates the computer's memory, logic, and control on a single chip.
Central Processing Unit (CPU) Area of the computer system that manipulates symbols, numbers, and letters, and controls the other parts of the computer system.
Primary Storage Part of the computer that temporarily stores program instructions and data being used by the instructions.
Arithmetic-logic Unit (ALU) Component of the CPU that performs the principal logic and arithmetic operations of the computer.
Control Unit Component of the CPU that controls and coordinates the other parts of the computer system.
RAM: Random Access Memory
ROM: Read Only Memory
PROM: Programmable ROM
What is RAM?
RAM: Random Access Memory
No moving parts
Accessed at electronic speeds
Volatile (electrical interruption loses data)
Programs and data are transferred to RAM from input devices or secondary storage
Nothing happens until data and program instructions are transferred from RAM to the CPU
Cache: a special kind of RAM, faster, more expensive, of smaller capacity
What is the difference between RAM and a floppy diskette?
RAM is primary storage, floppies are secondary storage.
RAM is volatile, floppies are non-volatile.
RAM is online, floppies are stored off-line and placed online as needed.
RAM represents bits with electrical current, floppies represent bits with a magnetic field.
Reads and interprets program instructions
Direct internal processor components
Moves programs and data in & out of RAM
Decoder: to decode instruction
Registers: to store instruction, data
Accumulator: to store results
Arithmetic & Logic Unit
Performs logic operations (>, <, =, AND, OR, XOR)
Series of operations that are necessary to operate a single program instruction
Involves the following elements:
Machine Cycle cont. 1. Fetch Instruction RAM to the Control Unit 2. Decode Instruction Control Unit 3. Execute Instruction ALU 4. Place Results in Memory ALU to RAM Instruction Time Execution Time
Micros: Megahertz (MHz)
RISC vs CISC architecture
Data Bus Width
RISC (reduced instruction set computing) Microprocessors that “have only the most frequently used instruction embedded in them”
MIPS: Millions of Instructions per second. MIPS are used to measure the speed of mainframes.
FLOPS: Floating point operations per second. A single floating point operation consists of multiple instructions (e.g. division). FLOPS are used to measure the speed of supercomputers.
Evolution of Computer Hardware
Vacuum tube technology - 1946-56
Transistors - 1957-63
Integrated Circuits - 1964-79
VLSI (Very Large Scale Integrated Circuits) - 1980-present
Intel’s 80486, 100 MHz
Intel’s Pentium, 200+ MHz
Intel’s Pentium II, 333 MHz
Intel’s Pentium III, 700+ MHz
Motorola, IBM, Apple’s PowerPC, 450+ MHz
Personal Computer (PC)
Small desktop or portable computer
Desktop computer with powerful graphics and mathematical capabilities
Computer designed to provide resources to other computers over a network
Used for high volume of business processing
Designed to support complex computations
Classifying computers continued
Differences blurring due to increased processor speed and storage capacities.
Classes such as “minicomputers” are being eliminated.
I/O intensive applications served by mainframes.
Processing intensive applications served by supercomputers.
Optical Laser Disks
W/R optical disks
Sequential Processing Parallel Processing: Type of processing in which more than one instruction can be processed at a time by breaking down a problem into smaller parts and processing them simultaneously with multiple processors.
Computer Networks and Client/Server Computing
Distributed processing: The distribution of computer processing work among multiple computers linked by a communications network.
Centralized processing: Processing that is accomplished by one large central computer.
Client/server computing: A model for computing that splits processing between "clients" and "servers" on a network, assigning functions to the machine most able to perform the function.
Client: The user point-of-entry for the required function in client server computing. Normally a desktop computer, workstation, or laptop computer.
Downsizing: The process of transferring applications from large computers to smaller ones.
Network computer (NC) Simplified desktop computer that does not store software programs or data permanently. Users download whatever software or data they need from a central computer over the Internet or an organization's own internal network.
Total cost of ownership (TCO) Designates the total cost of owning technology resources, including initial purchase costs, the cost of hardware and software upgrades, maintenance, technical support, and training.
In the past, information systems used magnetic tapes for sequential processing.
Today, magnetic tapes are primarily used for:
Backup of valuable files
File portability between computers
Provide random/direct processing of files
Floppy disks: Removable magnetic disk storage primarily used with PCs.
5 1/4 inch (1.2 MB)
3 1/2 inch (1.44 MB)
RAID (Redundant Array of Inexpensive Disks) Disk storage technology to boost disk performance by packaging more than 100 smaller disk drives with a controller chip and specialized software in a single large unit to deliver data over multiple paths simultaneously.
Magnetic Disks Tracks Sectors Read/Write Head Access Arm
R/W CD ROMS
Computer mouse: Handheld input device whose movement on the desktop controls the position of the cursor on the computer display screen.
Touch screen Input device technology that permits the entering or selecting of commands and data by touching the surface of a sensitized video display monitor with a finger or a pointer.
Source data automation: Input technology that captures data in computer-readable form at the time and place the data are created.
Optical character recognition (OCR): Form of source data automation in which optical scanning devices read specially designed data off source documents and translate the data into digital form for the computer.
Bar code: Form of OCR technology widely used in supermarkets and retail stores in which identification data are coded into a series of bars.
Magnetic ink character recognition (MICR): Input technology that translates characters written in magnetic ink into digital codes for processing.
Pen-based input: Input devices such as tablets, notebooks, and notepads consisting of a flat-screen display tablet and a pen-like stylus that digitizes handwriting.
Digital scanners: Input devices that translate images such as pictures or documents into digital form for processing.
Voice input devices: Technology that converts the spoken word into digital form for processing.
Sensors: Devices that collect data directly from the environment for input into a computer system.
Batch and On-Line Input and Processing
Batch processing: A method of collecting and processing data in which transactions are accumulated and stored until a specified time when it is convenient or necessary to process them as a group.
On-line processing: A method of collecting and processing data in which transactions are entered directly into the computer system and processed immediately.
A Comparison of Batch & On-line Processing
New Trends in Computer Hardware
Multimedia: Technologies that facilitate the integration of two or more types of media such as text, graphics, sound, voice, fulI-motion video, or animation into a computer based application.
Streaming technology Technology for transferring data so that they can be processed as a steady and continuous stream.
Massively Parallel Computers: Computers that use hundreds or thousands of processing chips to attack large computing problems simultaneously.
New Trends in Computer Hardware
Smart card: A credit card-size plastic card containing embedded storage and a microprocessor.