CHAPTER 2
Computer Systems
2.1
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COMPUTER GENERATIONS
1. VACUUM TUBES: 1946-1959
2.2
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COMPUTER GENERATIONS
1. VACUUM TUBES: 1946-1959
2. TRANSISTORS: 1957-1963
2.3
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COMPUTER GENERATIONS
1. VACUUM TUBES: 1946-1959
2. TRANSISTORS: 1957-1963
3. INTEGRATED CIRCUITS: 1964-1979
2.4
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COMPUTER GENERATIONS
1. VACUUM TUBES: 1946-1959
2. TRANSISTORS: 1957-1963
3. INTEGRATED CIRCUITS: 1964-1979
4. VERY LARGE-SCALE INTEGRATED
(VLSI) CIRCUITS: 1980- PRESENT
*
2.5
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SUPERCOMPUTER
TERAFLOP: TRILLION
CALCULATIONS/SECOND
• HIGHLY SOPHISTICATED
• COMPLEX COMPUTATIONS
• FASTEST CPUs
• LARGE SIMULATIONS
• STATE-OF-THE-ART COMPONENTS
• EXPENSIVE
*
2.6
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MAINFRAME
MIPS: Millions of Instructions per second
• LARGEST ENTERPRISE COMPUTER
• 5O MEGABYTES TO OVER ONE
GIGABYTE RAM
• COMMERCIAL, SCIENTIFIC,
MILITARY APPLICATIONS
• MASSIVE DATA
• COMPLICATED COMPUTATIONS
*
2.7
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MINICOMPUTER
• MIDDLE-RANGE
• 10 MEGABYTES TO OVER ONE
GIGABYTE RAM
• UNIVERSITIES, FACTORIES, LABS
• USED AS FRONT-END PROCESSOR
FOR MAINFRAME
*
2.8
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MICROCOMPUTER
• DESKTOP OR PORTABLE
• 64 KILOBYTES TO OVER 128
MEGABYTES RAM
• PERSONAL OR BUSINESS
COMPUTERS
• AFFORDABLE
• MANY AVAILABLE COMPONENTS
• CAN BE NETWORKED
*
2.9
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LAPTOPS & SMALLER
• LAPTOP (OR NOTEBOOK): Briefcase
type package, very portable, can be
inexpensive, can connect to other
computers or networks
• HAND-HELD (OR PALMTOP): Subminiature, wireless computer. Growing
in sophistication and connectivity
*
2.10
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BASIC COMPONENTS OF
COMPUTER SYSTEMS
• UNDERLYING STRUCTURE
• INPUT/OUTPUT
• BITS & CODING SCHEMES
• ARITHMETIC LOGIC UNIT
*
2.11
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CENTRAL PROCESSING UNIT
(CPU)
CONTROL UNIT
ROM
ARITHMETIC/LOGIC
UNIT
CLOCK
RAM
PRIMARY (MAIN) MEMORY
2.12
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BUSES
PRIMARY
CPU
STORAGE
DATA BUS
ADDRESS BUS
CONTROL BUS
2.13
INPUT
OUTPUT
SECONDARY
DEVICES
DEVICES
STORAGE
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TYPES OF MEMORY
• RAM : Random Access Memory
– Dynamic: Changes thru processing
– Static: Remains constant (power on)
• ROM : Read Only Memory
(preprogrammed)
– PROM: Program can be changed once
– EPROM: Erasable thru ultraviolet light
– EEPROM: Electrically erasable
*
2.14
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INPUT/OUTPUT
•
•
•
•
•
TERMINAL
POINT-OF-SALES TERMINALS
AUTOMATIC TELLER MACHINES
PUNCHED CARDS
MAGNETIC INK CHARACTER RECOGNITION
(MICR): Used by banks to process checks
*
2.15
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INPUT/OUTPUT
• OPTICAL CHARACTER RECOGNITION:
Scanned material translated into computer
characters
• IMAGING: Forms, documents, photos
digitized for computer use
• BAR CODE LABEL: Product label
information read into computer. Can be used
to track inventory
*
2.16
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INPUT/OUTPUT
• COMPUTER OUTPUT MICROFILM (COM):
Computer rapidly generates microfilm
documents for archive copies in small space
• VOICE RESPONSE UNITS: Computer
recognizes, generates verbal messages
• MULTIMEDIA: Combines text, graphics,
sound still images, animations, video
*
2.17
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HOW CHARACTERS ARE STORED
IN COMPUTER MEMORY
• BIT: Binary Digit. On/Off, 0/1, Magnetic/Not
• BYTE: Group of bits for one character
– EBCDIC- Extended Binary Coded Decimal
Interchange Code (8 bits per byte)
– ASCII- American Standard Code for
Information Exchange (7 or 8 bits per byte)
• PARITY BIT: extra bit added to each byte to
help detect errors
*
2.18
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EXAMPLES OF BYTES
EBCDIC
ASCII
(assume even-parity system)
C: 1100 0011 0
100 0011 1
A: 1100 0001 1
100 0001 0
T: 1110 0011 1
101 0100 1
Note how sum for each byte is an EVEN
number
*
2.19
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ALU & CONTROL UNIT
• ARITHMETIC- LOGIC UNIT: CPU
component performs logic and
arithmetic operations
• CONTROL UNIT: CPU component
controls, coordinates other parts of
computer system
*
2.20
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COMPUTER FILES
• RECORD: Data about a transaction
arranged in a set of FIELDS, each
holding a datum
• FILE: A group of similar records, such
as accounts receivable or payroll
• DATABASE: The files of an
organization, an electronic library
*
2.21
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COMPUTER FILES
• SEQUENTIAL ACCESS: A sequence of
files arranged in order, say
alphabetically. Usually stored on
magnetic tape or cartridge
• DIRECT ACCESS: Records stored on a
DIRECT ACCESS STORAGE DEVICE
(DASD). Can move directly to any
record
*
2.22
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DIRECT ACCESS STORAGE DEVICE
• HARD DISK: Steel platter array for
large computer systems
• RAID: Redundant array of Inexpensive
Disks
• FLOPPY DISK: Removable disk for PC
*
2.23
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DISK PACK STORAGE
• LARGE SYSTEMS
• RELIABLE STORAGE
• LARGE AMOUNTS OF DATA
• QUICK ACCESS & RETRIEVABLE
• TYPICAL: 11 2-SIDED DISKS
• CYLINDER: SAME TRACK ALL SURFACES
READ/WRITE
HEADS
DISK 1
DISK 2
DISK 3
DISK 4
DISK 5
CYLINDER 10: TRACK 10 (TOP AND BOTTOM OF EACH DISK)
2.24
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THE STORED PROGRAM CONCEPT
• COMPUTER IS A BINARY SYSTEM
• PROGRAM: A set of instructions telling
the computer what to do
• INSTRUCTION: Individual step or
operation in a program
• MACHINE LANGUAGE: Translated
instruction understood by particular
model of computer
2.25
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*
CONTROLLER
• LINK FOR INPUT/OUTPUT OR FILE
DEVICES: To CPU and memory of large
computer systems
• HIGHLY SPECIALIZED PROCESSOR:
Manages the operation of attached
devices to free the CPU from these
tasks
*
2.26
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DATA CHANNEL
• SPECIALIZED INPUT/OUTPUT
PROCESSOR (A COMPUTER): Takes
over function of device communication
from the CPU
• CORRECTS FOR SPEED MISMATCH
BETWEEN SLOW PERIPHERAL
DEVICES AND VERY FAST CPU
*
2.27
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SYMMETRIC MULTIPROCESSOR
• PROCESSORS (CPUs) ARE
IDENTICAL, WITH EACH
PROCESSOR OPERATING
INDEPENDENTLY OF THE OTHERS
• USED IN MOST MAINFRAMES AND
SOME MIDRANGE MACHINES
*
2.28
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PARALLEL PROCESSOR
(PP)
• MULTIPLE CPUs INSTALLED AS PART
OF A SINGLE COMPUTER SYSTEM:
Gives separate piece of program to
each of the processors so that work on
the program can proceed in parallel on
the separate pieces
*
2.29
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MASSIVELY PARALLEL
PROCESSOR (MPP)
PARALLEL PROCESSING COMPUTER WITH
MANY PARALLEL PROCESSORS:
• 32 OR MORE: Different CPUs capable of
performing different instructions at the same
time
• 1000 OR MORE: CPUs must all carry out the
same instruction at the same time
*
2.30
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CHAPTER 2
Computer Systems
2.31
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