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Using Information Technology
Chapter 4
Hardware--The CPU & Storage
Hardware--The CPU & Storage
How to Buy a Multimedia Computer System
4.1
Microchips, Miniaturization, & Mobility
4.2
The System Unit
4.3
Secondary Storage
4.1 Microchips, Miniaturization, & Mobility
From Vacuum Tubes to Transistors to Microchips
Vacuum Tubes – 18,000 in ENIAC in 1946.
Failed every 7 minutes, took 15 minutes to
replace!
Transistor (1st was 1/100th size of vacuum
tube) - a tiny electrically operated switch, or
gate, that can alternate between “on” and
“off” many millions of times per second
1960 – 1 transistor was ½ centimeter sq.
2003 – 3 million transistors on ½ cent sq.
1940s vacuum tube towering
over 1950s transistor
CHIP or MICROCHIP
•
A tiny piece of silicon (semiconductor) that
contains millions of micro-miniature electronic
components, mainly transistors. Silicon is found in
sand.
•
Microprocessor: Miniaturized circuitry of a
computer processor – the part that processes, or
manipulates data into information
4
Steps in Manufacture of a Microchip
1.
Make large drawing. Reduce drawing
hundreds of times to microscopic size.
2
Duplicate reduced photo many times on
sheet.
3
Print sheet of multiple copies on a wafer
made of silicon, a semiconductor.
4
Print layer after layer above and below
original silicon surface.
5
Cut wafer into chips.
6
Mount chip in frame with connective pins
extruding.
[Note: THEN transistors were individually formed.
Circuits attached w/wire & solder. TODAY integrated
circuits & wires are formed together in a single chip.
4.2 The System Unit
The Binary System: Using On/Off Electrical States
to Represent Data & Instructions
The binary system has only two
digits--0 and 1.
Bit - binary digit
Byte - group of 8 bits used to
represent one character, digit, or
other value
The Binary System: Using On/Off Electrical States
to Represent Data & Instructions
Kilobyte
1000 bytes
Megabyte
1,000,000 bytes (one million)
Gigabyte
1,000,000,000 bytes (one billion)
Terabyte
1 trillion bytes
Petabyte
1 quadrillion bytes
The Binary System: Using On/Off Electrical States to
Represent Data & Instructions
ASCII (American Standard Code for
Information Interchange) - the binary
code most widely used with
microcomputers
EBCDIC (Extended Binary Coded
Decimal Interchange Code) - used with
large computers
Unicode - uses two bytes for each
character rather than one.
Instead of 256 character
combinations of ASCII, 65,536
character combinations allow all
languages to be represented.
The Computer Case: Bays, Buttons & Boards
Bay - a shelf or opening used
for the installation of
electronic equipment
System unit - houses the
motherboard, power supply,
and storage devices
Case - empty box with just
power supply
Overhead view of system unit
The Motherboard & the Microprocessor Chip
Motherboard - the main circuit
board in the system unit
Expansion - increasing a
computer’s capabilities by
adding hardware
Upgrading - changing to
newer, more powerful
versions
The Motherboard & the Microprocessor Chip
Two principal architectures or designs of microprocessors:
CISC (Complex Instruction Set Computing) - Supports a large
number of instructions at relatively low processing speeds
RISC (Reduced Instruction Set Computing) - Supports a reduced
number of instructions in order to obtain faster processing speeds
Two kinds of microprocessors used in most microcomputers today:
Intel-type chips for P/Cs made by Intel, AMD, and others (Pentium. The
P4 has 42 million transistors)
Motorola-type chips made by Motorola for Apple Macintosh
computers
The Motherboard & the Microprocessor Chip

MICROPROCESSOR – contains a system clock, which controls how fast
all the operations within a computer takes place

System clock – uses fixed vibrations from a quartz crystal to deliver a
steady stream of digital pulses or “ticks” to the CPU.

Ticks are called cycles

Faster clock speeds result in faster processing and execution of program
instructions.
Steps in the machine cycle (Tick) [series of operations performed by
control unit to execute a single programmed instruction]:
1. Fetch an instruction
2. Decode the instruction
3. Execute the instruction
4. Store the result
Microprocessor speed expressed in Megahertz, a frequency equivalent to 1
million cycles (ticks) per second. (1 GHz - 1 billion cycles per second)

How Processor or CPU works: Control Unit, ALU, & Registers
CPU – Central processing unit (Brain):
consists of 2 parts (both contain
registers, high speed storage areas).
2 parts are linked by electronic
roadways “bus.”
1.
2.
Control unit – deciphers each instruction
stored in it and carries out. Directs
electrical signals bet main memory &
ALU & input/output devices.
Arithmetic Logic Unit – ALU –
performs arithmetic & logic operations
(comparisons) & controls speed
How Processor or CPU works: Control Unit, ALU, & Registers
BUS – bits are
transmitted within
the CPU and
between CPU &
other components of
motherboard.
Word size - # of
bits a processor
may process at one
time. 32-bit
“word”
microprocessor will
transfer data w/in
each processor chip
in 32-bit chunks.
How Memory Works: RAM, ROM, CMOS, & Flash
Types of memory chips:
1. RAM - Random Access Memory,
used to temporarily hold software
instructions & data in main
memory (volatile)
2.
3.
4.
ROM
CMOS
Flash
4 types of RAM chips:
1.
2.
3.
DRAM – Dynamic RAM – must be constantly refreshed
SDRAM – Synchronous DRAM – Synchronized by system clock, goes
faster
SRAM – Static RAM – doesn’t need to be refreshed, faster than DRAM
How Memory Works: RAM, ROM, CMOS, & Flash
Types of memory chips:
1.
2.
3.
4.
RAM
ROM - Read-Only Memory, which cannot be written
on or erased by the computer user. Contains fixed
start-up instructions
CMOS
Flash
How Memory Works: RAM, ROM, CMOS, & Flash
Types of memory chips:
1
2
3
4
RAM
ROM
CMOS - Complementary metal-oxide semiconductor;
powered by a battery and thus doesn’t lose its contents
when the power is off (non volatile)
Flash
How Memory Works: RAM, ROM, CMOS, & Flash
Types of memory chips:
1
2
3
4
RAM
ROM
CMOS
Flash memory chips – to store program - can be erased and
reprogrammed more than once (non volatile)
How Cache Works: Level 1 (Internal) & Level 2 (External)
Cache - temporary storage for instructions and data that the
processor is likely to use frequently, thus speeding up processing
Level 1 (L1) internal cache - built into the microprocessor (8-256
kilobytes – operates fast)
Level 2 (L2) external cache - consists of RAM chips outside
microprocessor (64-2MB)
Virtual memory - current operating systems allow for use of free
hard-disk space used to extend the capacity of RAM
Ports & Cables
Types of ports (connecting socket or jack on the outside of the
system unit into which are plugged different kinds of cables):
1
2
3
4
5
6
Serial port - sends bits one at a time, one after another
(keyboards, mouse, monitor, modem)
Parallel port
SCSI port
USB port
Dedicated port
Infrared port
Ports & Cables
1
2
3
4
5
6
Serial port
Parallel port transmits 8 bits
simultaneously (fast
data over short distances
– 15 ft) (printers,
external zip drive)
SCSI port
USB port
Dedicated port
Infrared port
Ports & Cables
1
2
3
4
5
6
Serial port
Parallel port
SCSI port - allows
fast data to be
transmitted in a
“daisy chain” to up to
7 devices
USB port
Dedicated port
Infrared port
Ports & Cables
1
2
3
4
5
6
Serial port
Parallel port
SCSI port
USB Port (universal serial bus) - can
theoretically connect up to 127
peripheral devices daisy-chained to one
general-purpose port (allows plug &
play – so peripheral devices & expansions
cards can be automatically configured
while they are being installed.
Dedicated port
Infrared port
Ports & Cables
1
2
3
4
5
6
Serial port
Parallel port
SCSI port
USB
Dedicated port special-purpose
ports
Infrared port
Dedicated ports: mouse port,
telephone jack, modem port, and
keyboard port
Ports & Cables
1
2
3
4
5
6
Serial port
Parallel port
SCSI port
USB
Dedicated port - specialpurpose ports
Infrared port - allows a
computer to make a
cableless connection with
infrared-capable devices
(handheld TV remote)
Expandability: Buses & Cards
(Open vs. closed architecture)
Expansion slots- sockets
on the motherboard into
which you can plug
expansion cards
Expansion cards - circuit
boards that provide more
memory or that control
peripheral devices
Expandability: Buses & Cards
ISA bus (industry standard architecture) - for ordinary low-speed
uses; the most widely used expansion bus
PCI bus (peripheral component interconnect)- for higher-speed
uses; used to connect graphics cards, sound cards, modems, and
high-speed network cards
AGP bus (accelerated graphics port) - for even higher speeds and
3D graphics
Note: system bus connects CPU to itself and to main memory
Expandability: Buses & Cards
Graphics cards - for monitors
Sound cards - for speakers and audio output
Modem cards - for remote communication via phone lines
Network interface cards - for remote communication via
cable
PC cards - for laptop computers (formally PCMCIA cards)
4.3 Secondary Storage
Floppy disk
a removable flat piece of mylar
plastic packaged in a 3.5-inch
plastic case
Data & programs are stored on
disks coating with magnetic spots
following on/off patterns of data
representation.
Tracks
sectors
DISK STORAGE
Floppy disk – 1.44 MB (400
typewritten pages)
Zip disks - 100 or 250 Mb
*SuperDisks - 120 Mb
*HiFD disks - 200 Mb
*Drive can also read floppy
Hard Disks
Hard disks - thin but rigid
metal platters covered with a
substance that allows data to
be held in the form of
magnetized spots
Read/write head does not
touch disk; rides on air
cushion
Hard Disks
Head crash - event that happens when the surface of the
read/write head or particles on its surface come into contact
with the surface of the hard-disk platter, causing the loss of
some or all of the data on the disk
Hard Disks
Nonremovable hard disks - housed in a microcomputer system
unit and used to store nearly all programs and most data files
See p. 164
Hard Disks
Removable hard disks - one
or two platters enclosed
along with read/write heads
in a hard plastic case, which
is inserted into a
microcomputer’s cartridge
drive
Bits on disk - dark stripes are 0
bits and bright stripes are 1 bits
Optical Disks: CDs & DVDs
Optical disk - a removable disk on which data is written and read
through the use of laser beams
Optical Disks: CDs & DVDs
CD-ROM - read only. For prerecorded text, graphics, and
sound
CD-R - for recording on once
CD-RW - for rewriting many
times
CD-Rom Drive’s speed denoted as data transfer by X which
represents rate of 150 kilobytes per second. (44X = 44x150 kb)
Optical Disks: CDs & DVDs
DVD-ROM - for reading only [extremely high capacity (4.711.7 gigabytes)
DVD-R - for recording on once
For rewriting many times:
DVD-RW
DVD-RAM
DVD+RW
Magnetic Tape (up to 66 gigabytes)
Magnetic tape - thin plastic
tape coated with a substance
that can be magnetized (for
1s) or left non-magnetized
(for 0s)
Tape cartridges - modules
resembling audio cassettes
that contain tape in
rectangular, plastic housings
Smart Cards
Smart card (holds up to 250 pgs of data)
Looks like a credit card but contains a
microprocessor embedded in the card (e.g.,
telephone debit card)
Optical card (holds up to 2000 pgs of data)
Plastic, laser-recordable, wallet-type card
used with an optical-card reader
[Note: conventional credit card strip holds
½ page of data]
Smart card in use
Flash Memory Cards
Flash memory card –
circuitry on credit-card-size
PC card that can be inserted
into slots connecting to the
motherboard
64 MB – projected up to 1
gigabyte
Concept Check
Which binary code is most often used with microcomputers?
ASCII (American Standard Code for Information
Interchange)
Concept Check
How many bytes are in a terabyte?
One trillion
Concept Check
Which type of CD can be written to only once?
CD-R
Concept Check
Which binary code can represent all the characters of virtually
every language in existence?
UNICODE
Concept Check
Which chip architecture provides faster processing speed-CISC or RISC?
RISC
Concept Check
Which measure of storage represents one billion bytes?
Gigabyte
Concept Check
What are the two parts of the CPU?
Control unit and arithmetic/logic unit (ALU)
Concept Check
What is the term for increasing a computer’s capabilities by
adding hardware to perform tasks beyond the scope of the
basic system?
Expansion
Concept Check
What is a gigahertz?
A measure of processing speed representing one billion cycles
per second
Concept Check
What is the term for the special high-speed memory area on a
chip that the CPU can access quickly?
Cache
Concept Check
What element are wafers composed of?
Silicon
Concept Check
What are the four steps of the machine cycle?
1.
2.
3.
4.
Fetch an instruction
Decode the instruction
Execute the instruction
Store the result