chapter2

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17 Νοε 2013 (πριν από 3 χρόνια και 11 μήνες)

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Chapter 2

Hardware


Trends in Computing Systems


Generally classified into three groups


Mainframe computers


Midrange (mini) computers


Microcomputers (PCs)

Microcomputer

Applications


Often referred to as personal computers


Many uses, styles, purposes


Workstations
-

High power PCs used for
analytical processing, mathematical
calculations, statistical analysis


Network Servers
-

Used to manage
resources on a network (usually a Local
Area Network)

Microcomputers (cont)


Personal Digital Assistants
-

Highly
specialized and mobile devises


Use special software to allow for optical
character recognition, touch pads, pen
-
based interface, etc.


This is the latest trend in communications
devices

Multimedia Systems


Personal computers with a variety of media
devices


Allow for more robust displays, music,
voice recognition and synthesis


More expensive than a traditional machine,
but much more useful and capable

Network computers


Designed primarily for work situations
where users access an Intranet (network
using Internet technologies


These machines usually have little or no
disk storage space


Main benefits are low cost, ease of
upgrades, manageable

Computer terminals


Dumb terminal
-

No processing occurs at
the terminal level. Usually associated with
a mainframe or client/server system


Intelligent terminals
-

Have the capability to
process at the local level (includes
transaction terminals in grocery store,
banks, department stores, etc)

Midrange Systems


Multi user systems that manage network
traffic, file access, device management


More powerful than a personal computer


Less powerful than a mainframe


Less costly to purchase, operate, maintain


Most efficient when scope of use is narrow
but processing needs are high

Midrange (cont)


Used largely in scientific research, process
control situations, engineering (CAD,
CAM, CAO)


Sometimes used as front end processors to
aid a mainframe system


Good devices for telecommunications and
network control (network servers)

Midrange (cont)


Can be used to host an Intranet, Extranet,
Internet, or client/server system


Can be configured and programmed to
operate virtually unaided


Do not require special climate controlled
areas

Mainframe Systems


Physically larger than midrange,
microcomputers, file servers


Can process more data and faster


Processing measured in MIPS (millions of
instructions per second)


High storage capacity


Require climate controlled operating areas

Mainframe Applications


Support the information and processing
needs of large corporations, government
offices, military


Can handle vast computational tasks


Super
-
server for communications need of
large client/server networks


Data warehousing

Supercomputer Applications


Used by major universities, multinational
corporations, largest government divisions


Cooperative applications between countries


Use multiple processors (any of which
could constitute as a mainframe)


$5million to $50 million cost

Components of a

Computer System


It is important to understand the
components of a computer as a system


Input > Processing > Output > Storage >
Control

Input


Input devices allow for the
feeding
of data
to the computer system


Keyboard/keypad


Touch screen


Light pens


Mouse


OCR


Voice activation

Processing


Central processing unit (microprocessor in a
personal computer)


Performs three functions


Control unit


Arithmetic
-
Logic unit


Primary storage unit

Output


Processed data in the form designated by
the user


Devices include


video display (monitors)


Audio response


Printers

Storage


Used to store programs (computer
instructions), data, processed information


Two types


Primary storage (main memory)


Secondary storage (magnetic disk, compact
disc, magnetic tape)

Control


The control unit manages and interprets
programs, transmission to other components
of the system


Is part of the CPU


other part is ALU


CPU contains
cache
memory

Primary Storage


Main memory
-

microelectronic
semiconductors


Commonly known as RAM (random access
memory)


Sometimes main memory can use ROM
(read only memory)


Loss of data if power loss

Secondary storage


Commonly known as
permanent
storage


Physical storage versus electronic storage


Support for primary storage

Multiple Processor Systems


Some systems use more than one processor
unit


Several configurations


Usually splits the control unit and the logic
unit

Multi Processor

Configurations


Support Processor
-

Free up the main
processor to execute program instructions
(can be a math co
-
processor, video display
controller or magnetic disk controller)


Coupled Processor
-

Used mostly to provide
for
fault tolerance


Parallel Processors
-

Execute instructions in
sequence

cont


Massively Parallel Processors
-

Many
processors aligned to execute hundreds or
thousands of instructions at the same time


RISC
-

Reduced Instruction Set Computer


Uses less instructions


Conclude chapter 2 next week


Complete coverage of chapter 3 next week