Transcript Stair Principles

Chapter 3
Hardware:
Input, Processing,
and Output Devices
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 calculations
Makes logical comparisons
Control unit
Sequentially accesses and decodes program instructions
Coordinates flow of data in and out of the ALU, registers,
primary storage, secondary storage, output devices
Registers
High-speed storage areas
Temporarily 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 phase
Step 1:
Step 2:
Fetch instruction
Decode instruction
Instruction time (I-time):
the instruction phase
The time to complete
Execution of an Instruction
Execution phase
Step 3:
Step 4:
Execute instruction
Store results
Execution time (E-time):
the execution phase
The time to complete
Execution of an Instruction
Fig 3.2
CPU Characteristics
Machine cycle time
Clock speed
Wordlength and bus line width
Physical characteristics
Complex and reduced instruction set computing
Machine Cycle Time
Measured in fractions of a second
Millisecond - one thousandth of one second
Microsecond - one millionth of one second
Nanosecond - one billionth of one second
Picosecond - 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
Microcode
Predetermined 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]
Wordlength
and Bus Line Width
Bit
A 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 Characteristics
of 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 capacity
Byte = eight bits
Kilo, Mega, Giga, Tera
Types of memory
Random access memory (RAM)
Temporary and volatile
Read-only memory (ROM)
Permanent and non-volatile
Cache memory
High-speed, quicker access than main memory
Basic Types of Memory Chips
Cache Memory
Multiprocessing
Processing that occurs using more than one
processing unit
Coprocessor
A 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
memory
An 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 access
Process 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 media
Mylar film coated with iron oxide
Magnetic disks
Steel platters
(hard disks) or
Mylar film (floppy
disks) coated
with 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 mirroring
Provides an exact copy of data on drive
Secondary Storage Devices
Optical disks
A 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 cards
Credit-card sized devices that can be installed in an
adapter or slot in many personal computers
Flash memory
A silicon chip that is nonvolatile and keeps its memory
when the power is shut off
Secondary Storage Devices
Expandable storage
Storage devices that use removable disk cartridges
Fig. 3.13
Secondary Storage Devices
Floptical disk
Experimental 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 data
Human-readable data vs. machine-readable data
Data entry and input
Data entry:
Human-readable data is converted into a
machine-readable
Data 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
 Terminals
devices
 Keyboard
 Mouse
 Voice recognition devices
 Digital computer cameras
 Scanning devices
 Optical data readers
 Optical mark recognition
readers
 Optical character reader
continued...
Input Devices
 Magnetic ink character
 Pen input devices
recognition (MICR) devices
 Point-of-sale (POS) devices
 Automatic teller machine
(ATM) 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 monitors
Monochrome
RGB (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 printers
Letter-quality printers, dot-matrix printers, near-letter
quality printers (NLQ)
Non-impact printers
Ink-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 computers
Used for limited applications
General-purpose computers
Most common type of computers
Used for a variety of applications
Types of Computer Systems
Personal computers
Network computers
Workstations
Midrange computers
Mainframes
Supercomputers
Types of Computer Systems
Personal computers
Relatively small and inexpensive
Also called microcomputers
Computer System Types
 Network Computers
 Stripped-down personal computers
 Primarily used with network system and the Internet
 Workstations
 Fit between high-end microcomputers and low-end
midrange computers in terms of cost and processing power
Computer System Types
Midrange computers
Systems that can accommodate several users at one time
Formerly known as minicomputers
Mainframes
Large powerful computers often shared by hundreds of
concurrent users connected to the machine via terminals
Supercomputers
Most powerful computer systems with the fastest
processing speeds
Network Computer
 Processor speed
 1-5 MIPs
 Amount of RAM
 4-16 MB
 Approximate cost
 $500-$1,500
 How used
 Supports data entry
 Connects to the Internet
 Example
 Oracle Network computer
Personal Computer
 Processor speed
 5-20 MIPs
 How used
 Improves individual worker’s
productivity
 Amount of RAM
 16-128 MB
 Approximate cost
 $1,200-$5,000
 Example
 Compaq Pentium computer
Workstation
 Processor speed
 50-100 MIPs
 Amount of RAM
 32-256 MB
 Approximate cost
 $4,000 to over $20,000
 How used
 Engineering CAD
 Software development
 Example
 Sun Microsystems computer
Midrange Computer
 Processor speed
 25-100 MIPs
 How used
 Meets computing needs for a
department or small company
 Amount of RAM
 32-512 MB
 Approximate cost
 $20,00 to over $100,000
 Example
 Hewlett-Packard HP-9000
Mainframe Computer
 Processor speed
 40-4,550 MIPs
 How used
 Meets computing needs for a
company
 Amount of RAM
 256-1,024 MB
 Approximate cost
 $250,000 to over
$2 million
 Example
 IBM ES/9000
Supercomputer
 Processor speed
 60 billion-3 trillion
instructions per sec
 Amount of RAM
 8,192MB+
 Approximate cost
 $2.5 million$3.5 million
 How used
 Scientific applications
 Marketing
 Customer support
 Product development
 Example
 Cray C90
Multimedia Computers
Involves the marriage of sound, animation, and
digitized video
Multimedia standards
Enable 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 compression
A 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.