Module 5Module 5
HardwareHardware
What Computers DoWhat Computers Do
Receive Input
Process Information
Produce Output
Store InformationStore Information
4 Primary Components of a Computer4 Primary Components of a Computer
Input Device
s
Storage Devices
Output Devices
Processing
Secondary
- hard disks
- removable disks
- CDs
- tapes
- keyboard
- mouse
- scanner
- digital camera
- touchpad
-CPU
-Control Unit
-Arithmetic & Logic Unit
- monitor
- printer
- speakers
Primary
- memory
- RAM
- ROM
Processing - CPUProcessing - CPU ““Central Processing Unit”Central Processing Unit” http://www.howstuffworks.com/microprocessor1.htm http://www.howstuffworks.com/microprocessor1.htm
evolution of processorsevolution of processors
the “brains” of the computer, where the “brains” of the computer, where calculations take placecalculations take place
two parts:two parts: ALU - Arithmetic Logic UnitALU - Arithmetic Logic Unit
• electronic circuitry that does all electronic circuitry that does all arithmetic and logic operationsarithmetic and logic operations
Control UnitControl Unit• circuitry that directs all other parts circuitry that directs all other parts
of the computerof the computer
Input DevicesInput Devices
accept input from the outside accept input from the outside world.world.
most common is the most common is the keyboardkeyboard, , followed by the followed by the mousemouse
sends signals to the computer, sends signals to the computer, telling it what you’ve “told” ittelling it what you’ve “told” it
Output DevicesOutput Devices
sends output to the outside worldsends output to the outside world
converts and displays the converts and displays the computer’s internal bit patterns to computer’s internal bit patterns to a format that humans can a format that humans can understandunderstand
Main output devices areMain output devices are monitors for immediate visual outputmonitors for immediate visual output printers for permanent paper outputprinters for permanent paper output
Screen OutputScreen Output
A monitor or video display terminal (VDT) A monitor or video display terminal (VDT) displays characters, graphics, displays characters, graphics, photographic images, animation and photographic images, animation and video.video. Video adapterVideo adapter —connects the monitor to the —connects the monitor to the
computercomputer VRAMVRAM or video memory—a special portion of or video memory—a special portion of
RAM to hold video images (the more video RAM to hold video images (the more video memory, the more detail of a picture memory, the more detail of a picture displayed)displayed)
Screen TalkScreen Talk
Monitor sizeMonitor size - measured as a diagonal line - measured as a diagonal line across the screen.across the screen.
PixelsPixels (or picture element) - tiny dots that (or picture element) - tiny dots that compose a picturecompose a picture
ResolutionResolution - the number of pixels - the number of pixels displayed on the screen (the higher the displayed on the screen (the higher the resolution, the closer together the dots)resolution, the closer together the dots)
Image QualityImage Quality
Image quality is affected Image quality is affected by by resolutionresolution and and color color depthdepth (or bit depth) (or bit depth)
Color depthColor depth refers to the refers to the number of different colors number of different colors a monitor displays at the a monitor displays at the same timesame time
Examples of Color DepthExamples of Color Depth
1-bit depth
16-bit depth8-bit depth
4-bit depth
Paper OutputPaper Output
Printers produce Printers produce paper output or hard paper output or hard copy copy
2 kinds of printers:2 kinds of printers: Impact printersImpact printers Non-impact printersNon-impact printers
Impact PrintersImpact Printers
Line printerLine printer Used by mainframes to Used by mainframes to
produce massive printoutsproduce massive printouts Limited to printing Limited to printing
characterscharacters
Dot matrix printerDot matrix printer Images created by a Images created by a
matrix of tiny dotsmatrix of tiny dots Low print qualityLow print quality Low costLow cost
Non-impact PrintersNon-impact Printers
A laser beam reflected A laser beam reflected off a rotating drum to off a rotating drum to create patterns of create patterns of electrical chargeselectrical charges
Faster and more Faster and more expensive expensive than dot matrix printerthan dot matrix printer
High-resolution outputHigh-resolution output
Laser Printer
More on Non-impact PrintersMore on Non-impact Printers
Sprays ink onto paper Sprays ink onto paper to produce printed text to produce printed text and graphic imagesand graphic images
Prints fewer Prints fewer pages/minute than laser pages/minute than laser printerprinter
High-quality color High-quality color costing less than laser costing less than laser printerprinter
Ink-jet Printer
Storage devicesStorage devices
Storage/Memory DevicesStorage/Memory Devices Divided into two groups:Divided into two groups:
Primary storagePrimary storage• usually a usually a temporarytemporary storage for the data and storage for the data and
programs currently in operation or currently programs currently in operation or currently being accessed.being accessed.
• it’s fastest and most expensiveit’s fastest and most expensive Secondary storageSecondary storage
• long-term long-term storage locationsstorage locations• cheap but slower than primary memorycheap but slower than primary memory• some are portable/removablesome are portable/removable• larger capacity than primary memorylarger capacity than primary memory
Primary Storage - RAMPrimary Storage - RAM
RAMRAM: Random Access Memory: Random Access Memory very fast - access times < 1 billionth of a second – in very fast - access times < 1 billionth of a second – in
nanosecondsnanoseconds volatile storagevolatile storage - once the computer is turned off, - once the computer is turned off,
everything is losteverything is lost this is where data and programs currently being used this is where data and programs currently being used
residereside a document that has not yet been “saved” is in RAM and will a document that has not yet been “saved” is in RAM and will
be lost if the computer freezes or the power goes offbe lost if the computer freezes or the power goes off
Primary Storage - ROMPrimary Storage - ROM ROM ROM = Read Only Memory= Read Only Memory permanentpermanent memory (doesn’t disappear if the memory (doesn’t disappear if the
computer is turned off)computer is turned off) normally holds the data/programs needed to start normally holds the data/programs needed to start
(“boot up”) the computer(“boot up”) the computer typically, cannot be altered except by physically typically, cannot be altered except by physically
changing the chipchanging the chip
ROMRAM
Secondary StorageSecondary Storage
Secondary storage devices are computer Secondary storage devices are computer peripherals capable of performing both peripherals capable of performing both input and output functions input and output functions
Information is stored semi-permanently on Information is stored semi-permanently on tape and disk drivestape and disk drives
Examples of storage devicesExamples of storage devices Magnetic tapes and disksMagnetic tapes and disks Zip, Jaz and SuperDisksZip, Jaz and SuperDisks Optical disksOptical disks
Secondary storage - Magnetic TapeSecondary storage - Magnetic Tape
Magnetic tapesMagnetic tapes Sequential access Sequential access Can store large amounts of information Can store large amounts of information
in a small space at a relatively low costin a small space at a relatively low cost Limitation: sequential accessLimitation: sequential access Used mainly for backup purposesUsed mainly for backup purposes
Magnetic MediaMagnetic Media Magnetic drivesMagnetic drives
Random accessRandom access Floppy disksFloppy disks for inexpensive, portable for inexpensive, portable
storagestorage
Hard disksHard disks are typically non-removable, are typically non-removable, rigid disks that spin continuously and rigid disks that spin continuously and rapidly thus providing much faster access rapidly thus providing much faster access than a floppy disk.than a floppy disk.
Removable mediaRemovable media (Zip & Jaz disks) (Zip & Jaz disks) provide high-capacity portable storage.provide high-capacity portable storage.
Hard DiskHard Disk magnetic storagemagnetic storage data is saved until something is written over it (or it data is saved until something is written over it (or it
gets damaged somehow)gets damaged somehow) data saved on “platters” and read with a “head” data saved on “platters” and read with a “head” platters spin at 3600-7200RPMplatters spin at 3600-7200RPM
head can move to center and back to edge about 50 head can move to center and back to edge about 50 times per secondtimes per second
platters divided into “tracks” and “sectors” to make it platters divided into “tracks” and “sectors” to make it easier to retrieve data. easier to retrieve data.
Optical MediaOptical Media
Not as fast as magnetic hard Not as fast as magnetic hard disksdisks
Massive storage capacity and Massive storage capacity and reliabilityreliability
Optical disk drive uses laser beams to read and write bits of information on the disk surface.
Types of Optical MediaTypes of Optical Media
CD-ROMCD-ROM drives are optical drives that drives are optical drives that readread CD-ROMs.CD-ROMs.
CD-RCD-R are are WORM WORM media (write-once, read media (write-once, read many). Hold about 700megabytes of infomany). Hold about 700megabytes of info
CD-RWCD-RW can read CD-ROMs and write (onto can read CD-ROMs and write (onto CD-R), erase and rewrite data onto CD-RW CD-R), erase and rewrite data onto CD-RW disks.disks.
DVDDVD (digital video disks) store & distribute all (digital video disks) store & distribute all kinds of data. They hold between 3.8 and 17 kinds of data. They hold between 3.8 and 17 gigabytes of information.gigabytes of information.
Solid-state Storage DevicesSolid-state Storage Devices
Flash memory is an erasable memory chip. Compact alternativeCompact alternative
No moving partsNo moving parts
Designed for specific applications such as Designed for specific applications such as storing pictures in digital camerasstoring pictures in digital cameras
Likely to eventually replace disk and tape Likely to eventually replace disk and tape storagestorage
ProcessingProcessing
The CPUThe CPU
The microprocessor that makes up your personal computer’s central processing unit, or CPU, is the
ultimate computer brain, messenger, ringmaster and boss. All the other components—RAM, disk drives, the monitor— exist only to bridge the gap between
you and the processor.
Ron White, in How Computers Work
The CPUThe CPU The CPU:The CPU:
interprets and executes interprets and executes instructionsinstructions
performs arithmetic and performs arithmetic and logical data manipulationslogical data manipulations
communicates with the communicates with the other parts other parts of the computer system.of the computer system.
The CPUThe CPU The CPU is a complex The CPU is a complex
collection of electronic collection of electronic circuits.circuits.
When all of those circuits are built into a single silicon chip, the chip is referred to as a microprocessor.
The circuit board that contains a computer’s CPU is called the motherboard or system board.
CPU
motherboard
CPU SpeedCPU Speed
A computer’s speed is determined in A computer’s speed is determined in part by the speed of its part by the speed of its internal clockinternal clock
The clock is a timing device that The clock is a timing device that produces electrical pulses to produces electrical pulses to synchronize the computer’s operations. synchronize the computer’s operations.
A computer’s clock speed is measured A computer’s clock speed is measured in units called in units called megahertz (MHz),megahertz (MHz), for for millions of clock cycles per second millions of clock cycles per second
CPU SpeedCPU Speed Parallel processingParallel processing
places multiple places multiple processors in a processors in a computer.computer.
Most supercomputers Most supercomputers have multiple processors have multiple processors that divide jobs into that divide jobs into pieces and work in pieces and work in parallel on the pieces.parallel on the pieces.
Ports and SlotsPorts and Slots
Tying things togetherTying things together
Ports and SlotsPorts and Slots
The system or motherboard includes several The system or motherboard includes several standard ports:standard ports:
Serial PortSerial Port for attaching devices that for attaching devices that send/receive messages one bit at a time send/receive messages one bit at a time (modems)(modems)
Parallel PortParallel Port for attaching devices that for attaching devices that send/receive bits in groups (printers)send/receive bits in groups (printers)
Keyboard/Mouse PortKeyboard/Mouse Port for attaching a keyboard for attaching a keyboard and a mouseand a mouse
More on Ports and SlotsMore on Ports and Slots Other ports are typically included on Other ports are typically included on
expansion boards rather than the system expansion boards rather than the system board:board: Video PortVideo Port used to plug in a color monitor into used to plug in a color monitor into
the video boardthe video board
Microphone, speaker, headphone, MIDI Microphone, speaker, headphone, MIDI portsports used to attach sound equipment used to attach sound equipment
SCSI portSCSI port allows several peripherals to be allows several peripherals to be strung together and attached to a single portstrung together and attached to a single port
Expansion Made EasyExpansion Made Easy
With the open architecture of the PC and the introduction of new interfaces, you can now hot swap devices.
USBUSB (Universal Serial Bus)(Universal Serial Bus) transmits a transmits a hundred times faster than a PC serial porthundred times faster than a PC serial port
Firewire (IEEE 1394)Firewire (IEEE 1394) can move data between can move data between devices at 400 or more megabits per seconddevices at 400 or more megabits per second
high speed makes it ideal for data-intensive work high speed makes it ideal for data-intensive work like digital video like digital video
Bits and BytesBits and Bytes
InformationInformation
Information comes in many forms
Computers store information in digital form
Text
12 3Numbers SoundsPictures
Bit BasicsBit Basics
A bit (binary digit)A bit (binary digit) is the smallest unit of is the smallest unit of
informationinformation can have two values: can have two values: 11 or or 00 can represent can represent numbersnumbers, , codescodes, , oror instructionsinstructions
On/off
Bits as NumbersBits as Numbers
Each switch can be used to store a tiny Each switch can be used to store a tiny amount of information, such as:amount of information, such as: An answer to a yes/no questionAn answer to a yes/no question A signal to turn on a lightA signal to turn on a light
Larger chunks of information are stored by Larger chunks of information are stored by grouping bits as unitsgrouping bits as units 8 bits (byte) = 256 different messages8 bits (byte) = 256 different messages
Bits As CodesBits As Codes
ASCII – American Standard Code for Information Interchange
Most widely used code, represents each character as a unique 8-bit code.
Bits as InstructionBits as Instruction
The computer stores instructions as The computer stores instructions as collections of bits. For instance, collections of bits. For instance, 01101010 might instruct the computer to 01101010 might instruct the computer to add two numbers.add two numbers.
Other bit instructions might include where Other bit instructions might include where to find numbers stored in memory or to find numbers stored in memory or where to store them.where to store them.
Bits, Bytes, and BuzzwordsBits, Bytes, and Buzzwords
ByteByte Kilobyte (KB)Kilobyte (KB) Megabytes (MB)Megabytes (MB) Gigabytes (GB)Gigabytes (GB) Terabytes (TB)Terabytes (TB)
= 8 bits= 8 bits
≈≈ 1 Thousand Bytes1 Thousand Bytes
≈≈ 1 Million Bytes1 Million Bytes
≈≈ 1 Billion Bytes1 Billion Bytes
≈≈ 1 Trillion Bytes1 Trillion Bytes
Terms used to describe file size or memory size:
The logic machineThe logic machine
How do we build a computer that doesn’t need to be How do we build a computer that doesn’t need to be rewired each time we want to perform a different task?rewired each time we want to perform a different task?
Connect the components in such a way that the Connect the components in such a way that the program itself controls the “rewiring” by signaling the program itself controls the “rewiring” by signaling the hardware to switch the components on and off in the hardware to switch the components on and off in the proper sequenceproper sequence
Logic GatesLogic Gates
Using switches, we can reproduce the logical Using switches, we can reproduce the logical operatorsoperators ANDAND OROR NOTNOT
0 = false = off0 = false = off
1 = true = on1 = true = on
ANDAND
PP QQ PQPQ
00 00 00
00 11 00
11 00 00
11 11 11
AND is written like a
multiply
OROR
PP QQ P+QP+Q
00 00 00
00 11 11
11 00 11
11 11 11
OR is written like anadditio
n
NOTNOT
PP P’P’
00 11
11 00
NOT is written with an ’ after
the letter
Simple Truth TableSimple Truth Table
PP QQ PQ + P’Q’PQ + P’Q’
(result)(result)
00 00 11
00 11 00
11 00 00
11 11 11
“if both P and Q are the same,
then the result is true”
Example: Example: check to see if P and Q are equalcheck to see if P and Q are equal
Step 1: build Truth TableStep 1: build Truth Table The truth table for The truth table for “P and Q are equal”“P and Q are equal” looks like: looks like:
PP QQ ResultResult
00 00 11
00 11 00
11 00 00
11 11 11
P = 0, Q = 0 they are equal
so result is true (1)
P = 1, Q = 1 they are equal, so result is true
(1)
Step 2:Step 2:
Build an AND statement for each line where Result = 1Build an AND statement for each line where Result = 1
PP QQ ResultResult
00 00 11
11 11 11 P AND Q = PQ
P’ AND Q’ = P’Q’
the ’ means NOT… so P’
means that P is off/0
Step 3:Step 3:
Join each line with OR-statementsJoin each line with OR-statements
P’Q’
PQOR
result = P’Q’ + PQ
Example 2:Example 2:
PP QQ SS
00 00 11
00 11 00
11 00 11
11 11 11
Step 1: Build Truth Table … already done for us
P’Q’
PQ’
PQ
Step 2: Build equation terms using ANDs
PP QQ SS
00 00 11
00 11 00
11 00 11
11 11 11
S = P’Q’ + PQ’ + PQ
P’Q’
PQ’
PQ
Step 3: Build equation by joining terms from step 2 with ORs
Drawing circuitsDrawing circuits
GatesGates
ANDAND == ** = =
OROR == ++ ==
NOTNOT = = ’ ’ ==
Two inputs
One output
Two inputs
One output
One output
One input
Gates to switchesGates to switches
Logical gates can be converted to physical Logical gates can be converted to physical switches that operate exactly as expectedswitches that operate exactly as expected
We can combine gates to act like our statements We can combine gates to act like our statements from the truth tables since we have a gate for from the truth tables since we have a gate for each of AND, OR, NOTeach of AND, OR, NOT
Building CircuitsBuilding Circuits
We build the circuit in the exact same We build the circuit in the exact same order as we build the equationorder as we build the equation figure out the inputsfigure out the inputs do all the NOTsdo all the NOTs next all the ANDSnext all the ANDS lastly all the ORslastly all the ORs
ExampleExample
Result = PQ + P’Q’Result = PQ + P’Q’
Step A: Inputs
P
Q
One input (light switch) for
each letter in the equation
Step B: NOTsStep B: NOTs
Result = PQ + P’Q’
P
Q
P’
Q’
P
Q
Step C: ANDsStep C: ANDs
Result = PQ + P’Q’
P
Q
Remember AND is the same as a
multiply
P
Q
PQ
P’
Q’
P’Q’
Step D: ORsStep D: ORs
Result = PQ + P’Q’
P
Q
Remember OR is the same as addition
The light will light up when the
inputs are both the same, as
described in the truth table
PQ
P’Q’
PQ + P’Q’
ExampleExample3 inputs, light-up if exactly 2 inputs are true3 inputs, light-up if exactly 2 inputs are true
XX YY ZZ ResultResult
00 00 00 00
00 00 11 00
00 11 00 00
00 11 11 11
11 00 00 00
11 00 11 11
11 11 00 11
11 11 11 00
Step 1: Build Truth Table
XX YY ZZ ResultResult
00 00 00 00
00 00 11 00
00 11 00 00
00 11 11 11
11 00 00 00
11 00 11 11
11 11 00 11
11 11 11 00
Step 2: build terms with ANDs (where result is true)
X’YZ
XY’Z
XYZ’
Step 3: Build equation by joining terms with ORs
result = X’YZ + XY’Z + XYZ’
Step 4: Build circuitStep 4: Build circuit
Step A: InputsStep A: Inputs
result = X’YZ + XY’Z + XYZ’
X
Y
Z
Step B: NOTsStep B: NOTs
result = X’YZ + XY’Z + XYZ’
X
Y
Z
X’
Y’
Z’
Step C: ANDsStep C: ANDs
result = X’YZ + XY’Z + XYZ’
X
Y
Z
X’
YX’Y
Y’
XXY’
Y
XXY
ZX’YZ
ZXY’Z
Z’XYZ’
result = X’YZ + XY’Z + XYZ’
X
Y
Z
X’YZ
XY’Z
XYZ’
result = X’YZ + XY’Z + XYZ’
X
Y
Z
X’YZ
XY’Z
XYZ’
X’YZ + XY’Z
X’YZ + XY’Z+ XYZ’
Using Loggo to combine gatesUsing Loggo to combine gates
Go to the class homepage and look for the Go to the class homepage and look for the LoggoLoggo applet in the Miscellaneous sectionapplet in the Miscellaneous section
Try implementing different equations to see if Try implementing different equations to see if they match the truth tablesthey match the truth tables
Corresponding ReadingsCorresponding Readings
Chapter 2Chapter 2 Chapter 3Chapter 3
Vocabulary/definitionsVocabulary/definitions Truth tables / circuitsTruth tables / circuits
From a description, write truth tableFrom a description, write truth table From truth table, write equationFrom truth table, write equation From equation, build circuitFrom equation, build circuit
To Know – Module 5To Know – Module 5