Hardware: physical computer components
Consider software before hardware
Computer must handle four operations
Accept data
Store data
Process data
Output data
Input devices: receive signals from outside of computer and transfer them into computer
Central processing unit
Accepts instructions and data
Decodes and executes instructions
Stores output in memory
Internal memory: stores data and instructions before and after CPU processes them
RAM: random access memory
ROM: read-only memory
Motherboard: CPU and primary memory reside
External Memory: magnetic disks, magnetic tapes, optical discs, DVDs, and flash memory
Allows permanent storage
Output devices: deliver information from computer to person
Most commonly monitors and printers
Includes audio devices
Bit: Binary digit
0 or 1
Byte: a standard group of eight bits
Most characters represented by single byte
Computers vary in size
Classified by power
Depends on processing speed and memory size
More powerful computers are more expensive
Supercomputers: most powerful computer at any given time
Largest in physical size and most expensive
Parallel processing: multiple processors running simultaneously
Also known as multiprocessing
Mainframe computers: store large amounts of data and business transactions
Less expensive and less powerful than supercomputers
Banks, universities, and insurance companies use them as a central computer
40-50% of world’s business data resides on mainframes
Use multiple processors
Midrange computers: often act as servers within organizations or through the Internet
Smaller and less powerful than mainframes
Serves hundred of users that connect from personal computers
Use multiple processors
Microcomputers: personal computers, notebook computers, and handhelds
Workstation: more powerful microcomputer used for CAD, CAM, and scientific applications
Power doubles about every two years
Notebook computer: compact personal computer powered by rechargeable battery
New models include wireless technology
Personal digital assistant: handheld computer
Stylus used to enter data through touch screen
Tablet computer: PC on a thick writing tablet
Technology convergence: build several technologies into single piece of hardware
Prominent in handheld units
Commonly merged technologies include
Cell phones
Television
Digital cameras
MP3 players
Professionals must know computer components to understand its power and capabilities
Use the knowledge to make good decisions in purchasing a computer
CPU has two units to store and process data
Control unit and arithmetic logic unit
CPU is silicon chip with multiple circuits
Also known as microprocessor
Modern processors can do multithreading
Processing more than one program at a time
Microprocessors are embedded with transistors
Transistor is a semiconductor that can represent binary code’s two states
Machine Cycle (CPU):
Fetch, decode execute each instruction
Data word: maximum number of bits that the control unit can fetch
Arithmetic Logic Unit: arithmetic and logic
Computer power depends on processing speed and memory capacity
Bus: electronic lines or traces used for communication inside computer
Throughput: number of bits per second bus can accommodate
MIPS: millions of instructions per second, a common measure of computer speed
Computers must receive input to produce output
Input devices include machines used to enter instructions and data into computer
Most common input device is keyboard
Contains keys that users press to enter data
Includes letters, numbers, and punctuation
QWERTY and Dvorak: QWERTY standard
Dvorak facilitates faster typing
Ergonomic keyboard: fits the natural position of forearms and prevents injury
Mouse: controls onscreen pointer to facilitate point-and-click approach
Trackball: similar to mouse, but ball moves within device
Trackpad: cursor controlled by touch-sensitive pad
Mice and similar devices can be wireless units
Touch screen: both input and output device
Often used for public applications
Prevalent in handheld devices
Source data input devices: copy data directly from source
Bar-codes, credit cards, and checks
Use optical recognition devices, which detect positions of marks or characters
Magnetic-ink character recognition: detects magnetic ink on checks
Imaging: converting documents into images
Saves paper
More efficient retrieval and filing
Scanned document can be destroyed
Translating human speech into computer-readable data and instructions
Receive input from microphone and process with software
May increase noise level in offices is Speech Recognition
Most popular devices are monitors and printers
Other output includes speakers
In the future, smell output is possible
Cathode-ray tube: inner side of screen has layer of phosphoric dots called pixels
Electron gun receives instructions from computer and sweeps the pixels
Flat-panel monitor: includes liquid crystal display, which uses a liquid crystal filled screen, whose molecules align in different places when given electric charge
Nonimpact printer: does not mechanically impact the paper
Laser printer is most common in business
Others: ink-jet and electrothermal printers
Impact printers: reproduce image by using mechanical impact
Dot-matrix printer has pins that strike ink ribbon against paper
Data must be stored on nonvolatile medium
Data is retained even when not powered
Storage devices differ in technology used to maintain data and physical structure
Sequential storage: data is organized one record after another
Slower and less convenient
Direct access: records are organized by physical address on the device
Flash drives: small storage devices that connect via universal serial bus
Direct access storage media is only practical way to organize and query databases
Magnetic tapes: similar to tape recorders and VCRs
Provide lowest cost (bytes per dollar)
Can backup all data
Takes long time to copy from tape
Unreliable after a long period of time
Magnetic disk: most widely used storage medium
Hard disk: stack of several aluminum platters installed in same box that holds CPU
Stores up to 500 GB of data
External hard disks connect to computer through USB port
Optical disc: recorded by treating disc surface to reflect light in different ways
Compact discs: available as read-only, recordable, and rewritable
DVDs: store 4.7 GB per side
Optical discs are slower than hard disks
Optical tape uses same technology as optical discs to store and retrieve data
Bits are organized sequentially like tape
Used in digital video camcorders
Flash memory: memory chip that can be rewritten and holds content without power
Available as memory card and USB drive
Solid state disk: storage media that does not have latency time
Direct access storage: disk or array of disks directly connected to server
Network-attached storage: device designed for networked storage
Storage area network: network fully devoted to storage and transfer of data
DAS, NAS, and SAN utilize RAID, redundant array of independent disks
When purchasing storage devices managers must consider:
How the data is used
Capacity of the device
Speed and cost
Reliability and portability
Companies must consider the following when deciding what to purchase:
Power of the equipment
Expansion slots and ports
Monitor type and resolution
Ergonomics
Other factors include:
Compatibility with existing hardware
Physical size of computer
Reliability of vendor
Power consumption and noise
Scalability: resources can be expanded or upgraded to provide increased power
Not all hardware is scalable
Leasing hardware is a valid option to avoid short useful lifetime of hardware
Understanding hardware is important for purchasing decisions
Computers classified according to power
All computers have CPU to process instructions
Clock rate measures the speed of a CPU
Computer word is the number of bits it can process in a single cycle
Computer power: speed and memory size
RAM is volatile memory that forms a large part of computer’s memory
ROM is nonvolatile: does not require power
Imaging devices help process text and graphics
When evaluating external storage, consider density, transfer rate, capacity,
Data organized sequentially on tapes
Direct access storage devices include RAM, magnetic disks, and optical discs
Databases require direct access storage devices
When purchasing hardware, managers should consider power, scalability, and compatibility
Information technology may pose health risks such as carpel tunnel syndrome
