Hardware: Input, Processing, and Output Devices Chapter 3
Jan 15, 2016
Hardware:
Input, Processing, and Output Devices
Chapter 3
Computer System
Special subsystem of an organization's overall information system
Integrated assembly of physical devices, centered around at least one processing mechanism utilizing digital electronics
Used to input, process, store, and output data and information
Computer System Components
[Figure 3.1]
Computer system hardware components include devices that perform the functions of input, processing, data storage, and output.
Central Processing Unit (CPU)
Arithmetic/logic unit (ALU)Performs mathematical calculationsMakes logical comparisons
Control unitSequentially accesses and decodes program instructionsCoordinates flow of data in and out of the ALU, registers, primary
storage, secondary storage, output devices
Registers High-speed storage areasTemporarily hold small units of program instructions and data
immediately before, during, and after execution by CPU
Primary Storage
Holds program instructions and data immediately before or immediately after the registers
Also called memory or main memory
Closely associated with the CPU
Execution of an Instruction
Instruction phaseStep 1: Fetch instructionStep 2: Decode instruction
Instruction time (I-time): The time to complete the instruction phase
Execution of an Instruction
Execution phaseStep 3: Execute instructionStep 4: Store results
Execution time (E-time): The time to complete the execution phase
Execution of an Instruction
Fig 3.2
CPU Characteristics
Machine cycle timeClock speedWordlength and bus line widthPhysical characteristicsComplex and reduced instruction set computing
Machine Cycle Time
Measured in fractions of a secondMillisecond - one thousandth of one secondMicrosecond - one millionth of one secondNanosecond - one billionth of one secondPicosecond - one trillionth of one second
Or in terms of instructions per second MIPS - millions of instructions per second
Clock Speed
Predetermined rate at which the CPU produces a series of electronic pulses
MicrocodePredetermined internal instructions executed in
accordance with clock speed
Often measured in megahertz (MHz) or millions of cycles per second; ranges from 20 MHz to over 200 MHz for PCs
Clock Speed and the Execution of Microcode Instructions
[Figure 3.3]
Wordlengthand Bus Line Width
BitA binary digit: 0 or 1
Wordlength Number of bits the CPU can process at any one time
Bus lines Physical wiring that connects computer system
components
Physical Characteristicsof the CPU
Moore’s Law: The hypothesis that transistor densities on a single chip will double every 18 months
[Figure 3.4]
CISC and RISC
Complex instruction set computing (CISC)Places as many microcode instructions into the central
processor as possible
Reduced instruction set computing (RISC)Reduces the number of microcode instructions built into a
chip to an essential set of common instructions
Memory
Storage capacityByte = eight bits
Kilo, Mega, Giga, Tera
Types of memoryRandom access memory (RAM)
Temporary and volatile
Read-only memory (ROM)Permanent and non-volatile
Cache memoryHigh-speed, quicker access than main memory
Basic Types of Memory Chips
Cache Memory
Multiprocessing
Processing that occurs using more than one processing unit
CoprocessorA processor that speeds processing by executing specific
types of instructions while the CPU works on another processing activity
Parallel Processing
Speeds processing by linking several processors to operate at the same time
Parallel Processing
Shared memory processing (SMP) Involves fewer processors and a common pool of main
memoryAn independent task runs on each processor
Massively parallel processing (MPP) Involves hundreds or thousands of microprocessor chips
assigned to do the computing for a single program
Parallel Processing
[Figure 3.8]
Secondary Storage
The portion of the computer that holds large amounts of data, instructions, and information more permanently than does main memory
Also called permanent storage
Cost Comparison of Various Forms of Data Storage
[Figure 3.9]
Access Method Trade-Offs
Direct accessProcess by which data and information are retrieved
directly, without the need to pass by other data in sequence
Sequential access storage device (SASD)Device used to sequentially access secondary storage
media
Access Method Trade-Offs
Direct access storage device (DASD) Device used to directly access secondary storage media
Secondary Storage Devices
Magnetic tape Common secondary storage mediaMylar film coated with iron oxide
Magnetic disksSteel platters
(hard disks) or Mylar film (floppy disks) coatedwith iron oxide
Fig. 3.11
Secondary Storage Devices
Redundant array of independent/ inexpensive disks (RAID)Generates extra bits of data from existing data so the
system can create a “reconstruction map” to rebuild lost data
Disk mirroringProvides an exact copy of data on drive
Secondary Storage Devices
Optical disksA rigid disk of plastic onto which data is recorded by
special lasers that physically burn pits into the disk
Compact disk read-only memory (CD-ROM) A common form of optical disk on which data, once
recorded, cannot be modified
Secondary Storage Devices
CD-rewriteable (CD-R)Allows PC users to replace their diskettes with high
capacity CDs that can be written upon and edited over
Write-once, read-many (WORM) Allows businesses to record customized data and
information onto an optical disk
Secondary Storage Devices
Magneto-optical disk A hybrid between magnetic disks and optical disks
Digital video disk (DVD)Looks like a CD-ROM
disk, but can store about 135 minutes of digital video
Fig. 3.12
Secondary Storage Devices
Memory cardsCredit-card sized devices that can be installed in an
adapter or slot in many personal computers
Flash memoryA silicon chip that is nonvolatile and keeps its memory
when the power is shut off
Secondary Storage Devices
Expandable storageStorage devices that use removable disk cartridges
Fig. 3.13
Secondary Storage Devices
Floptical diskExperimental storage device that is the same size as a
diskette, but is able to hold many more times the data
Comparison of Secondary Storage Devices
[Table 3.2]
Speed And Functionality
The nature of dataHuman-readable data vs. machine-readable data
Data entry and inputData entry: Human-readable data is converted into a
machine-readableData input: Machine-readable data is transferred into the
system
continued...
Speed And Functionality
Source data automation Automation of data entry and input where the data is
created, thus ensuring accuracy and timeliness
Input Devices
Personal computer input devicesKeyboardMouse
Voice recognition devices
Digital computer cameras
Terminals
Scanning devices
Optical data readersOptical mark recognition
readersOptical character reader
continued...
Input Devices
Magnetic ink character recognition (MICR) devices
Point-of-sale (POS) devices
Automatic teller machine (ATM) devices
Pen input devices
Light pens
Touch-sensitive screens
Bar code scanners
Sample Input Device: Digital Computer Camera
Fig. 3.14
Sample Input Device: MICR Device
Fig. 3.15
Output Devices: Monitors
Display monitorsMonochromeRGB (red, green, blue)Color graphics adapter (CGA)Enhanced graphics adapter (EGA)Video graphics array (VGA)Extended graphics array (XGA)
Liquid crystal display (LCDs)
Output Devices: Printers, Plotters,and Microfilm
Impact printersLetter-quality printers, dot-matrix printers, near-letter
quality printers (NLQ)
Non-impact printersInk-jet printers and laser printers
Plotters Computer output microfilm devices (COM)Special-Purpose Devices: Multifunction device
A device that combines several input/output devices (e.g., printer, fax, scanner)
Classifying Computers
Special-purpose computersUsed for limited applications
General-purpose computers Most common type of computersUsed for a variety of applications
Types of Computer Systems
Personal computersNetwork computersWorkstationsMidrange computersMainframesSupercomputers
Types of Computer Systems
Personal computersRelatively small and inexpensiveAlso called microcomputers
Computer System Types
Network ComputersStripped-down personal computersPrimarily used with network system and the Internet
WorkstationsFit between high-end microcomputers and low-end
midrange computers in terms of cost and processing power
Computer System Types
Midrange computersSystems that can accommodate several users at one timeFormerly known as minicomputers
MainframesLarge powerful computers often shared by hundreds of
concurrent users connected to the machine via terminals
SupercomputersMost powerful computer systems with the fastest
processing speeds
Network Computer
Processor speed1-5 MIPs
Amount of RAM4-16 MB
Approximate cost$500-$1,500
How usedSupports data entryConnects to the Internet
ExampleOracle Network computer
Personal Computer
Processor speed5-20 MIPs
Amount of RAM16-128 MB
Approximate cost$1,200-$5,000
How usedImproves individual worker’s
productivity
ExampleCompaq Pentium computer
Workstation
Processor speed50-100 MIPs
Amount of RAM32-256 MB
Approximate cost$4,000 to over $20,000
How usedEngineering CADSoftware development
ExampleSun Microsystems computer
Midrange Computer
Processor speed25-100 MIPs
Amount of RAM32-512 MB
Approximate cost$20,00 to over $100,000
How usedMeets computing needs for a
department or small company
ExampleHewlett-Packard HP-9000
Mainframe Computer
Processor speed40-4,550 MIPs
Amount of RAM256-1,024 MB
Approximate cost$250,000 to over
$2 million
How usedMeets computing needs for a
company
ExampleIBM ES/9000
Supercomputer
Processor speed60 billion-3 trillion
instructions per sec
Amount of RAM8,192MB+
Approximate cost$2.5 million-
$3.5 million
How usedScientific applicationsMarketingCustomer supportProduct development
ExampleCray C90
Multimedia Computers
Involves the marriage of sound, animation, and digitized video
Multimedia standardsEnable software and hardware vendors to build products
that will work together to meet the needs of their customers
Multimedia Support
Microsoft multimedia extension for Windows
Multimedia PC Council (MPC)
IBM Ultimedia Solution
Multimedia Support: Audio
Musical Instrument Digital Interface (MIDI)Standard system for connecting musical instruments and
synthesizers to computers
Digital signal processor (DSP)A chip used by advanced sound systems to improved the
analog-to-digital-to-analog conversion process
Multimedia Support: Video
Video compressionA process that uses mathematical formulas to reduce the
number of bits required to present a single video frame
Hardware Components of Multimedia Computer System
[Figure 3.18]
Architecture and Upgrades: Responding to Change
Computer system architecture The structure, or configuration, of hardware components
of a computer system
Computer Standards
Approved reference models determined by groups for building various products
Common PC standards:Plug and play (PnP) Small Computer Systems Interface (SCSI)Multimedia extension (MMX)
Information Systems Principles
Assembling an efficient computer subsystem requires an understanding of its relationship to the information system and the organization. The computer system objectives are subordinate to, but supportive of, the information system and the organization.
Information Systems Principles
Components of information systems (input devices, people, procedures, goals) are interdependent. Because the performance of one system affects the others, all systems should be measured according to the same standards of effectiveness and efficiency.
Information Systems Principles
When selecting computer subsystem devices, consider current and future needs. The choice of a particular computer system should allow for later improvements in the overall information system. Reasoned forethought is the hallmark of a true systems professional.
Information Systems Principles
Determine hardware needs based on how the hardware will be used to support the objectives of the information systems and the goals of the organization. For PC users, this means knowing what software you want to run.
Information Systems Principles
Do research to gain an understanding of the trade-offs between overall system performance, and cost, control, and complexity.