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1
Inside “The Box”
2
CRT Display
Keyboard
Mouse
“The Box”CD-ROM Drive
FloppyDiskDrive
Computing Devices – Old and New
3
Motherboard
4
CPU(Central Processing Unit)
5
SIMM(Single Inline Memory Module)
6
HDD(Hard Disk Drive)
7
Power Supply
8
Schematic Diagram of a Personal Computer...
Ports
CPU
RAM
Diskcontroller
Graphicscard
Soundcard
Networkcard
Printer
Mouse
Keyboard
ModemMonitor
Speakers
bus
Computer
Schematic Diagram of a Personal Computer...
10
Data Formats
Textbook: Chapter 4
11
Figure 3.1 Data conversion and representation
Data input
12
Introduction
• Examples (discreet, continuous)
Real World
Data
Computer
DataInput device
Dear Mom: Keyboard 10110010…
Digitalcamera
10110010…
13
Format must be Appropriate
• The internal representation must be appropriate for the type of processing to take place (e.g., text, images, sound)
• Problem: Since computers store everything in binary code, how does it know what a particular stored item is?
14
Rules/Conventions
• Proprietary formats– Unique to a product or company– E.g., Microsoft Word, Corel Word Perfect, IBM Lotus
Notes
• Standards– Evolve two ways:
• Proprietary formats become de facto standards (e.g., Adobe PostScript, Apple Quick Time)
• Committee is struck to solve a problem (Motion Pictures Experts Group, MPEG)
Text : pg 63-64
15
Standards Organizations
• ISO – International Standards Organization
• CSA – Canadian Standards Association
• ANSI – American National Standards Institute
• IEEE – Institute for Electrical and Electronics Engineers
Rv.kc
16
Examples of StandardsType of Data Standards
Alphanumeric ASCII, EBCDIC, Unicode
Image JPEG, GIF, PCX, TIFF
Motion picture MPEG-2, Quick Time,MP4
Sound Sound Blaster, WAV, AU,MP3
Outline graphics/fonts
PostScript, TrueType, PDF
Hint - Learn What kind is which!
17
Why Standards?• Standards are “arbitrary”
• They exist because they are:– Convenient– Efficient– Flexible– Appropriate
Plus, they provide some consistency andpredictability for applications.
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18
Alphanumeric Data• Problem: Distinguishing between the number 123 (one
hundred twenty-three) and the characters “123” (one, two, three)
• In software: data is given a type• Four Main standards for representing letters (alpha)
and numbers– BCD – Binary-coded decimal– ASCII – American standard code for information interchange– EBCDIC – Extended binary-coded decimal interchange
code– Unicode
19
Standard Alphanumeric Formats
• BCD (Binary Coded Decimal)
• ASCII
• EBCDIC
• Unicode
20
Next slides
Standard Alphanumeric Formats
• BCD
• ASCII
• EBCDIC
• Unicode
21
The Problem
• Representing text strings, such as “Hello, world”, in a computer
After all, computers store binary digits, not letters!
22
Codes and Characters
• Each character is coded as a byte
• Most common coding system is ASCII (Pronounced ass-key)
• ASCII = American National Standard Code for Information Interchange
• Defined in ANSI document X3.4-1977
23
ASCII Features
• 7-bit code• 8th bit is unused (or used for a parity bit or
to indicate “extended” character set)• 27 = 128 codes• Two general types of codes:
– 95 are “Graphic” codes (displayable on a console)– 33 are “Control” codes (control features of the
console or communications channel)
R/kc
24
+/Kc
Memorize codes for: blank space,
period, digit zero (0),capital A,small a,carriage return
(CR)
Hint
25
ASCII chart0 1 2 3 4 5 6 7
0 NULL DLE 0 @ P ` p1 SOH DC1 ! 1 A Q a q2 STX DC2 " 2 B R b r3 ETX DC3 # 3 C S c s4 EDT DC4 $ 4 D T d t5 ENQ NAK % 5 E U e u6 ACK SYN & 6 F V f v7 BEL ETB ' 7 G W g w8 BS CAN ( 8 H X h x9 HT EM ) 9 I Y i yA LF SUB * : J Z j zB VT ESC + ; K [ k {C FF FS , < L \ l |D CR GS - = M ] m }E SO RS . > N ^ n ~F SI US / ? O _ o DEL
26
e.g., ‘a’ = 1100001
Example: character ‘a’0 1 2 3 4 5 6 7
0 NULL DLE 0 @ P ` p1 SOH DC1 ! 1 A Q a q2 STX DC2 " 2 B R b r3 ETX DC3 # 3 C S c s4 EDT DC4 $ 4 D T d t5 ENQ NAK % 5 E U e u6 ACK SYN & 6 F V f v7 BEL ETB ' 7 G W g w8 BS CAN ( 8 H X h x9 HT EM ) 9 I Y i yA LF SUB * : J Z j zB VT ESC + ; K [ k {C FF FS , < L \ l |D CR GS - = M ] m }E SO RS . > N ^ n ~F SI US / ? O _ o DEL
27
Code types: 95 graphic codes0 1 2 3 4 5 6 7
0 NULL DLE 0 @ P ` p1 SOH DC1 ! 1 A Q a q2 STX DC2 " 2 B R b r3 ETX DC3 # 3 C S c s4 EDT DC4 $ 4 D T d t5 ENQ NAK % 5 E U e u6 ACK SYN & 6 F V f v7 BEL ETB ' 7 G W g w8 BS CAN ( 8 H X h x9 HT EM ) 9 I Y i yA LF SUB * : J Z j zB VT ESC + ; K [ k {C FF FS , < L \ l |D CR GS - = M ] m }E SO RS . > N ^ n ~F SI US / ? O _ o DEL
28
See text page 69 / 71 for details
Code types: 33 control codes0 1 2 3 4 5 6 7
0 NULL DLE 0 @ P ` p1 SOH DC1 ! 1 A Q a q2 STX DC2 " 2 B R b r3 ETX DC3 # 3 C S c s4 EDT DC4 $ 4 D T d t5 ENQ NAK % 5 E U e u6 ACK SYN & 6 F V f v7 BEL ETB ' 7 G W g w8 BS CAN ( 8 H X h x9 HT EM ) 9 I Y i yA LF SUB * : J Z j zB VT ESC + ; K [ k {C FF FS , < L \ l |D CR GS - = M ] m }E SO RS . > N ^ n ~F SI US / ? O _ o DEL
29
Code types: alphabetic codes0 1 2 3 4 5 6 7
0 NULL DLE 0 @ P ` p1 SOH DC1 ! 1 A Q a q2 STX DC2 " 2 B R b r3 ETX DC3 # 3 C S c s4 EDT DC4 $ 4 D T d t5 ENQ NAK % 5 E U e u6 ACK SYN & 6 F V f v7 BEL ETB ' 7 G W g w8 BS CAN ( 8 H X h x9 HT EM ) 9 I Y i yA LF SUB * : J Z j zB VT ESC + ; K [ k {C FF FS , < L \ l |D CR GS - = M ] m }E SO RS . > N ^ n ~F SI US / ? O _ o DEL
30
Code types: numeric codes0 1 2 3 4 5 6 7
0 NULL DLE 0 @ P ` p1 SOH DC1 ! 1 A Q a q2 STX DC2 " 2 B R b r3 ETX DC3 # 3 C S c s4 EDT DC4 $ 4 D T d t5 ENQ NAK % 5 E U e u6 ACK SYN & 6 F V f v7 BEL ETB ' 7 G W g w8 BS CAN ( 8 H X h x9 HT EM ) 9 I Y i yA LF SUB * : J Z j zB VT ESC + ; K [ k {C FF FS , < L \ l |D CR GS - = M ] m }E SO RS . > N ^ n ~F SI US / ? O _ o DEL
31
Code types: punctuation codes, etc.0 1 2 3 4 5 6 7
0 NULL DLE 0 @ P ` p1 SOH DC1 ! 1 A Q a q2 STX DC2 " 2 B R b r3 ETX DC3 # 3 C S c s4 EDT DC4 $ 4 D T d t5 ENQ NAK % 5 E U e u6 ACK SYN & 6 F V f v7 BEL ETB ' 7 G W g w8 BS CAN ( 8 H X h x9 HT EM ) 9 I Y i yA LF SUB * : J Z j zB VT ESC + ; K [ k {C FF FS , < L \ l |D CR GS - = M ] m }E SO RS . > N ^ n ~F SI US / ? O _ o DEL
32
“Hello, world” Example
============
Hexadecimal48656C6C6F2C207767726C64
Decimal72
1011081081114432
119103114108100
Hello, world
============
33
Common Control Codes
• CR 0D carriage return
• LF 0A line feed
• HT 09 horizontal tab
• DEL 7F delete
• NULL 00 null
Hexadecimal code
34
Common control codes in the table
0 1 2 3 4 5 6 70 NULL DLE 0 @ P ` p1 SOH DC1 ! 1 A Q a q2 STX DC2 " 2 B R b r3 ETX DC3 # 3 C S c s4 EDT DC4 $ 4 D T d t5 ENQ NAK % 5 E U e u6 ACK SYN & 6 F V f v7 BEL ETB ' 7 G W g w8 BS CAN ( 8 H X h x9 HT EM ) 9 I Y i yA LF SUB * : J Z j zB VT ESC + ; K [ k {C FF FS , < L \ l |D CR GS - = M ] m }E SO RS . > N ^ n ~F SI US / ? O _ o DEL
35
Terminology
• Names of special symbols
• [ ] brackets
• { } braces
• ( ) parentheses
• @ commercial ‘at’ sign
• & ampersand
• ~ tilde
36
Special symbols in the table0 1 2 3 4 5 6 7
0 NULL DLE 0 @ P ` p1 SOH DC1 ! 1 A Q a q2 STX DC2 " 2 B R b r3 ETX DC3 # 3 C S c s4 EDT DC4 $ 4 D T d t5 ENQ NAK % 5 E U e u6 ACK SYN & 6 F V f v7 BEL ETB ' 7 G W g w8 BS CAN ( 8 H X h x9 HT EM ) 9 I Y i yA LF SUB * : J Z j zB VT ESC + ; K [ k {C FF FS , < L \ l |D CR GS - = M ] m }E SO RS . > N ^ n ~F SI US / ? O _ o DEL
37
Escape Sequences
• Extend the capability of the ASCII code set• For controlling terminals and formatting output• Defined by ANSI in documents X3.41-1974 and
X3.64-1977
• The escape code is ESC = 1B16
• An escape sequence begins with two codes:
ESC [ 1B16 5B16
38
Examples
• Erase display: ESC [ 2 J
• Erase line: ESC [ K
39
Next slides
Standard Alphanumeric Formats
• BCD
• ASCII
• EBCDIC
• Unicode
40
Unicode
• 16-bit standard
• Developed by a consortia
• Intended to supercede older 7- and 8-bit codes
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Unicode Version 2.1
• 1998
• Improves on version 2.0
• Includes the Euro sign (20AC16 = )
• From the standard:…contains 38,887 distinct coded characters derived from the supported scripts. These characters cover the principal written languages of the Americas, Europe, the Middle East, Africa, India, Asia, and Pacifica.
http://www.unicode.org
42
Keyboard Input
• Key (“scan”) codes are converted to ASCII
• ASCII code sent to host computer
• Received by the host as a “stream” of data
• Stored in buffer
• Processed
• Etc.
43
Figure 3.7 Keyboard operation
Keyboard to binary
44
Shift Key
• inhibits bit 5 in the ASCII code
Key(s)
ASCII code
6 5 4 3 2 1 0 Character
1 1 0 0 0 0 1
1 0 0 0 0 0 1
a
A
a
aShift
45
Control Key
• inhibits bits 5 & 6 in the ASCII code
Key(s)
ASCII code
6 5 4 3 2 1 0 Character
1 1 0 0 0 1 1
0 0 0 0 0 1 1
c
ETX
c
cCtrl
Controlcode
46
Data Input Devices
• OCR – optical character recognition
• Bar code readers
• Voice/audio input
• Punched cards
• Images / objects
• Pointing devices
pp. Old: 69-86Rev: 72-89
47
OCR
Hello, world
Page of text
Optical scan 10110110…
Computer file
48
Data Input Devices
• OCR – optical character recognition
• Bar code readers
• Voice/audio input
• Punched cards
• Images / objects
• Pointing devices
pp. 69-86
49
Bar Codes• An automatic identification (Auto ID)
technology that streamlines identification and data collection
• See: http://www.digital.net/barcoder/barcode.html
50
Data Input Devices
• OCR – optical character recognition
• Bar code readers
• Pointing devices
• Punched cards
• Voice/audio input
• Images / objects
pp. 69-86
51
Pointing Devices
• Originally used for specifying coordinates (x, y) for graphical input
• Today used as general purpose device for “graphical user interfaces” (GUIs)
52
Data Input Devices
• OCR – optical character recognition
• Bar code readers
• Pointing devices
• Punched cards
• Voice/audio input
• Images / objects
pp. 69-86
53
Punched Cards
• Invented by Herman Hollerith (founder of IBM)
• Each card holds 80 characters
54
Image data
• Typically images are pictures that are optically scanned and saved as a “bit map” or in some other format
• Many formats– gif, jpeg, …
Note: animated gifs often used on www
55
Typical “Save As” Dialog
56
Types of images
• Bitmaps (raster images)– Examples: photographs, pointing devices– Continuous variation of color, shape, texture– Entered via a scanner or video camera
• Object images– Created with specialized drawing programs– Set of graphical objects (lines, rectangles,
etc.)
57
Bitmap images
• Made of pixels• Require a lot of memory (600 x 800 x 3 = 1.4
MB)• Resolution – defines the detail level of the image• Involve little processing• Formats
– GIF (limited to 256 colors)– JPEG (up to 16 Million of colors; use compression)
Bitmap Images
• Used for realistic images with continuous variations in shading, color, shape and texture
• Preferred when image contains large amount of detail and processing requirements are fairly simple
• Input devices: – Scanners– Digital cameras and video capture devices– Graphical input devices like mice and pens
• Managed by photo editing software or paint software
4-58
Bitmap Images
• Each individual pixel, for pi[x]cture element, in a graphic is stored as a binary number– Pixel: A small area with an associated coordinate
location
– Example: each point below represented by a 4-bit code corresponding to 1 of 16 shades of gray
4-59
Bitmap Display
• Monochrome: black or white– 1 bit per pixel
• Gray scale: black, white or 254 shades of gray– 1 byte per pixel
• Color graphics: 16 colors, 256 colors, or 24-bit true color (16.7 million colors)– 4, 8, and 24 bits respectively
4-60
61
Figure 3.10 GIF screen layout
GIF format
62
Figure 3.11 GIF file format layout
GIF image format
JPEG (Joint Photographers Expert Group)
• Allows more than 16 million colors• Suitable for highly detailed photographs
and paintings• Employs lossy compression algorithm that
– Discards data to decreases file size and transmission speed
– May reduce image resolution, tends to distort sharp lines
4-63
Bitmap vs. Object ImagesBitmap (Raster) Object (Vector)
Pixel map Geometrically defined shapes
Photographic quality Complex drawings
Paint software Drawing software
Larger storage requirements Higher computational requirements
Enlarging images produces jagged edges
Objects scale smoothly
Resolution of output limited by resolution of image
Resolution of output limited by output device
4-64
Video Images
• Require massive amount of data– Video camera producing full screen 1024 x
768 pixel true color image at 30 frames/sec 70.8 MB of data/sec
– 1-minute film clip 4.25 GB storage• Options for reducing file size: decrease
size of image, limit number of colors, or reduce frame rate
• Video format determined by a codec, encoder/decoder
4-65Copyright 2013 John Wiley & Sons, Inc.
Video Images• Best known codec standards: MPEG-2,
MPEG-4, and H.264– Data may be compressed to 10-60 MB or less of
data per minute• Container serves as a superstructure to
encode, decode, hold and stream the video– Examples: Quicktime from Apple, WebM from
Google, and Flash Video from Adobe• Streaming video: video displayed in real time
as it is downloaded from the Web server
4-66Copyright 2013 John Wiley & Sons, Inc.
Audio Data
• Transmission and processing requirements less demanding than those for video
• Analog Waveform: digital representation of sound
• Analog sound converted to digital values by A-to-D converter
• MIDI (Musical Instrument Digital Interface): instructions to recreate or synthesize sounds
4-67Copyright 2013 John Wiley & Sons, Inc.
Waveform Audio
Sampling rate normally 50KHz
4-68Copyright 2013 John Wiley & Sons, Inc.
Sampling Rate
• Number of times per second that sound is measured during the recording process.– 1000 samples per second = 1 KHz (kilohertz)– Example: Audio CD sampling rate = 44.1KHz
• Height of each sample saved as:– 8-bit number for radio-quality recordings– 16-bit number for high-fidelity recordings– 2 x 16-bits for stereo
4-69Copyright 2013 John Wiley & Sons, Inc.
Audio Formats
• MP3 – predominant digital audio data format– Derivative of MPEG-2 (ISO Moving Picture Experts
Group)– Uses psychoacoustic lossy compression techniques
to reduce storage requirements• WAV
– Developed by Microsoft as part of its multimedia specification
– General-purpose format for storing and reproducing small snippets of sound
– Non-compressed 8- or 16-bit sound samples
4-70Copyright 2013 John Wiley & Sons, Inc.
Audio Data Formats
4-71Copyright 2013 John Wiley & Sons, Inc.
WAV file
Data Compression
• Compression: recoding data so that it requires fewer bytes of storage space.
• Compression ratio: the amount file size is reduced• Lossless: inverse algorithm restores data to exact
original form– Examples: GIF, PCX, TIFF, ZIP
• Lossy: trades off data degradation for file size and download speed– Much higher compression ratios, often 10 to 1– Example: JPEG, MP3 – Common in multimedia
• H.264: uses both forms for ratios of 1000:1
4-72Copyright 2013 John Wiley & Sons, Inc.