Digital Electronics/Printable version

From Wikibooks, open books for an open world
Jump to navigation Jump to search


Digital Electronics

The current, editable version of this book is available in Wikibooks, the open-content textbooks collection, at
https://en.wikibooks.org/wiki/Digital_Electronics

Permission is granted to copy, distribute, and/or modify this document under the terms of the Creative Commons Attribution-ShareAlike 3.0 License.


Number Base System

In digital electronics how information is represented is key and there are different radices, i.e. number bases, that a numbering system can use, with the most common ones being: binary (base-2), octal (base-8), decimal (base 10) and hexadecimal (base 16). When a reference is made to a numbering system's base, i.e. its' radix, the base number represents the number of digits used in that numbering system. As an example, we are all familiar with the decimal numbering system and the digits used it are: 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9. The numbering systems that have a base/radix less than 10 recycle the "digits" used to be common with the decimal numbering system. Therefore, the digits for binary are: 0 and 1, the digits for octal are: 0, 1, 2, 3, 4, 5, 6 and 7. For the hexadecimal numbering system, base 16, the digits are: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F.

The decimal numbering is obviously linked to the fact that us humans have 10 fingers...10 digits. However, the other "common" numbering systems in digital electronics are linked to logic, in particularly boolean logic and boolean algebra as developed by George Boole. In logic, including the philosophical kind, there can only be two answers: TRUE or FALSE. In digital electronics, we can represent TRUE as a high voltage (historically 5 Volts, but it has changed to save power) which we denote as a 1 and we represent FALSE as low voltage (0 Volts, but lower voltages can also be used too) which we denote as a 0. Therefore, with two values to work with we then have the binary numbering system. The octal numbering is simply a more compact group of three binary digits. So instead of having to type "101" we can just type "5"; assuming that the numbering system is known to be octal based. In a similar manner, hexadecimal based numbering system is based on a grouping of four binary digits, so "D" is easier to type instead of "1101"

Beyond Digits, Representing Numbers[edit | edit source]

Now that we understand a numbering system's radix, the next step is to use these digits to present numbers, ideally large numbers. Independent of the numbering system's radix, the order of digits as they are listed in the representation of a number is of GREAT "significance", pardon the pun, and needs to be fully understood to be able to use any numbering system properly; even the decimal numbering system. The digit furthest to the right has a numerical weight of , which is always 1 given that any number raised to the zero power is one. The next digit moving to the left has a numerical weight of , which is the first digit where the radix value begins to being a factor. The weighting for each subsequent digit continues to increase by one with respect to the "power" that the radix is raised. And like in our more traditional decimal numbering systems there are ALWAYS zero digits in front of the highest weighted digit, but we simply do not bother writing all those zeros as such zeroes are not significant. The same is true with other radices, hence the order of the digits is representing a number in any radix is significant.

The next sections provide illustrations on how numbers are represented in the differing radices.

Number of Base Two[edit | edit source]

Base two numbers only use the two digits 0 and 1 . Any number greater than 1 is represented by a series of 0 and 1 digits

= 14

Numbers that contain only two digit 0 and 1 are called Binary Numbers. Each 0 or 1 is called a Bit, from binary digit. A binary number of 4 bits is called a Nibble. A binary number of 8 bits is called a Byte. A binary number of 16 bits is called a Word on some systems, on others a 32-bit number is called a Word while a 16-bit number is called a Halfword.

Using 2 bit 0 and 1 to form

a binary number of 1 bit, there are 2 such numbers 0 and 1
a binary number of 2 bit, there are 4 such numbers 00, 01, 10, 11
a binary number of 3 bit, there are 8 such numbers 000, 001, 010, 011, 100, 101, 110, 111
a binary number of 4 bit, there are 16 such numbers 0000, 0010, 0100, 0110, 1000, 1010, 1100, ..., 1111

Therefore , using n bits there are 2n binary numbers of n bits

Numbers of Base Ten[edit | edit source]

Base ten numbers use ten digits, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9. Any number greater than 9 is represented by a series of digits in the 0 through 9 range.

Numbers of Base sixteen(hexa decimal)[edit | edit source]

Base sixteen numbers use sixteen digits 0,1,2,3,4,5,6,7,8,9,a,b,c,d,e,f. any number greater than 15 is represented by digits in the 0 through f range.


Communication (Conversion) between numbers of Different base[edit | edit source]

The same number 14 expressed

in base ten is 14
in base two is 1110 .

Hence, any number in our base ten system can be represented by a binary number of certain bit



Logic Operations

Logic Operation[edit | edit source]

Logic BUFFER perform a logic operation on a input . Output is the same as Input
Logic NOT perform a logic operation on a input . Output is the invert of Input
Logic AND perform a logic operation on two input to yield a result at the output. Output is High only when both Inputs are High
Logic OR perform a logic operation on two input to yield a result at the output. Output is Low only when both Inputs are Low
Logic XOR perform a logic operation on two input to yield a result at the output. Output is Low only when both Inputs are the same and Output is High only when both Inputs are different

Digital Logic Equation[edit | edit source]

If A and B is Input and Y as Output then

Logic BUFFER → Y = A
Logic NOT → Y = NOT A
Logic AND → Y = A AND B
Logic OR → Y = A OR B
Logic XOR → Y = A XOR B

Digital Truth Table[edit | edit source]

The logic operation of any logic above can be summarized in a table called a truth table.

If High is 1 and Low is 0 then

Digital Gates Construction[edit | edit source]

Each Logic can be constructed from electronic components to form a circuit of a device called Digital Gates to perform the logic operation



Mathematical Operations

Basic Mathematics[edit | edit source]

Addition[edit | edit source]

0 + 0 = 0
0 + 1 = 1
1 + 0 = 1
1 + 1 = 1 0

Subtraction[edit | edit source]

0 - 0 = 0
0 - 1 = 0 1
1 - 0 = 1
1 - 1 = 0

Multiplication[edit | edit source]

0 x 0 = 0
0 x 1 = 0
1 x 0 = 0
1 x 1 = 1

Division[edit | edit source]

0 / 0 = x
0 / 1 = 0
1 / 0 = x
1 / 1 = 1

Logic Mathematics[edit | edit source]

NOT AND OR XOR NAND



Building Circuits with Breadboards

One of the best ways to learn how digital circuits work is to build them with an inexpensive solderless breadboard.

Solderless breadboard with 400 connection points

They typically come in three sizes

  • mini
  • half (around 400 connection points)
  • full



Logic Gates

Family Logic Gates[edit | edit source]

  1. Fundamental Digital Gates
  2. Combinational Gates
  3. Basic Logic Gates Summary
  4. Logic NAND

Reference[edit | edit source]



Logic Gates/Fundamental Digital Gates

Digital Gates[edit | edit source]

Digital gate is a Digital Device used to perform the logic operation on the input(s) to produce an equivalent logic in the output. The output produced from the inputs are listed in a table called a Truth table. The relation between output and inputs can also be represented by a mathematic equation .

There are 5 basic digital gates used to perform Logic Operation namely Buffer, NOT, AND, OR, XOR

Basic Digital Gates[edit | edit source]

Basic Logic Gates Symbol Mathmatical Formula Truth Table
Buffer Buffer ANSI Labelled.svg Q = A
A Q
0 0
1 1
NOT NOT ANSI Labelled.svg Q = NOT A
A Q
0 1
1 0
AND AND Gate Q = A . B
A B Q
0 0 0
0 1 0
1 0 0
1 1 1
OR Logic-gate-or-us.png Q = A + B
A B Q
0 0 0
0 1 1
1 0 1
1 1 1
XOR XOR ANSI Labelled.svg Q = A (+) B
A B Q
0 0 0
0 1 1
1 0 1
1 1 0



Logic Gates/Combinational Gates

Combination gates[edit | edit source]

More than one logic gates can be connected to produce new logic gates

Buffer[edit | edit source]

Basic Logic Gates Combinational Gates Symbol Mathmatical Formula Truth Table
Buffer Logic-gate-inv-us.png Cổng NOT (NOT Gate) Buffer ANSI Labelled.svg Y = is NOT NOT A
Y = A
A Q
0 0
1 1

NOT Gate[edit | edit source]

Digital Gate Combinational Gates Symbol Mathematical Expression Truth Table
NOT Gate Buffer ANSI Labelled.svg Cổng NOT (NOT Gate) Cổng NOT (NOT Gate) Y = is NOT A A Y
0 1
1 0

NAND Gate[edit | edit source]

Digital Gate Combinational Gate Symbol Mathematical Expression Truth Table
Buffer Logic-gate-and-us.png Cổng NOT (NOT Gate) Logic-gate-nand-us.png Y = is NOT A.B A B Y
0 0 1
0 1 1
1 0 1
1 1 0

NOR Gate[edit | edit source]

Digital Gate Combinational Gate Symbol Mathematical Expression Truth Table
NOT Logic-gate-or-us.png Cổng NOT (NOT Gate) Logic-gate-nor-us.png Y = is NOT A+B A B Y
0 0 1
0 1 0
1 0 0
1 1 0

XNOR Gate[edit | edit source]

Basic Gates Combinational Gate Symbol Mathematical Formula Truth Table
NOT Gate XOR ANSI Labelled.svg Logic-gate-inv-us.png XNOR ANSI Labelled.svg Y = is NOT AxorB A B Q
0 0 1
0 1 0
1 0 0
1 1 1
XNOR Aufbau.png XNOR using NOR.svg



Logic Gates/Basic Logic Gates Summary

Logic Gates Summary[edit | edit source]

The table below summarize all the Basic Digital Gates and their characteristics

Basic Logic Gates Symbol Mathmatical Formula Truth Table
Buffer Buffer ANSI Labelled.svg Q = A A Q
0 0
1 1
NOT NOT ANSI Labelled.svg Q = NOT A A Q
0 1
1 0
AND AND Gate Q = A . B A B Q
0 0 0
0 1 0
1 0 0
1 1 1
NAND AND Gate Q = NOT (A . B) A B Q
0 0 1
0 1 1
1 0 1
1 1 0
OR Logic-gate-or-us.png Q = A + B A B Q
0 0 0
0 1 1
1 0 1
1 1 1
NOR Logic-gate-nor-us.png Q = NOT (A + B) A B Q
0 0 1
0 1 0
1 0 0
1 1 0
XOR XNOR ANSI Labelled.svg Q = (A + B) . NOT (A . B) A B Q
0 0 0
0 1 1
1 0 1
1 1 0
XNOR XNOR ANSI Labelled.svg Q = NOT ( (A + B) . NOT (A . B) ) A B Q
0 0 1
0 1 0
1 0 0
1 1 1



Logic Gates Summary

The table below summarize all the Basic Digital Gates and their characteristics

Basic Logic Gates Symbol Mathmatical Formula Truth Table Constructions
Buffer Buffer ANSI Labelled.svg Q = A A Q
0 0
1 1
NOT NOT ANSI Labelled.svg Q = NOT A A Q
0 1
1 0
AND AND Gate Q = A . B A B Q
0 0 0
0 1 0
1 0 0
1 1 1
NAND AND Gate Q =NOT (A . B) A B Q
0 0 1
0 1 1
1 0 1
1 1 0
OR Logic-gate-or-us.png Q = A + B A B Q
0 0 0
0 1 1
1 0 1
1 1 1
NOR Logic-gate-or-us.png Q = NOT (A + B) A B Q
0 0 1
0 1 0
1 0 0
1 1 0
XOR XOR ANSI Labelled.svg Q = A + B A B Q
0 0 0
0 1 1
1 0 1
1 1 0
XNOR XNOR ANSI Labelled.svg Q = A + B A B Q
0 0 0
0 1 1
1 0 1
1 1 1



Mathematic and Logic Operations

  1. Digital Adder
  2. Digital Subtractor
  3. Digital Decoder
  4. Digital Encoder



Synchronous Device

Synchronous Device[edit | edit source]

  1. Flip Flop
  2. Register
  3. Counter



Asychronous Device

Asychronous Device[edit | edit source]

  1. Digital Multiplexer
  2. Digital DeMultiplexing



Digital Data

Digital Data[edit | edit source]

Digital Data is a Binary Numbers of two bits 0 and 1 . A 0 & 1 could be

  1. 0v & 5v
  2. Switch Opened & Switch Closed
  3. High & Low

Data Communication[edit | edit source]

Parallel In Parallel Out[edit | edit source]

Input Data is entered in Parallel and get out in Parallel

Data In --> Data Out

0 --> 0
1 --> 1
0 --> 0
1 --> 1

Parallel In Series Out[edit | edit source]

Input Data is entered in Parallel and get out in Series

Data In

0
1
0
1

Data Out

0101



Data Encoder

Digital Encoder Introduction[edit | edit source]

Digital Encoder is a Digital Device that uses binary number of n bit to represent a number of base ten . Binary number of n bit is called Binary Coded Decimal (BCD), a coding scheme used in digital to encode informations

If there are two control lines A and B , we can have 4 4-bit-binary-numbers a3a2a1a0 which can be used to represent a number of base ten from 0 to 3

A B a3 a2 a1 a0 Decimal Number
0 0 0 0 0 0 0
0 1 0 0 0 1 1
1 0 0 0 1 0 2
1 1 0 0 1 1 3

Digital Encoder Types[edit | edit source]

BCD - Binary Coded Decimal[edit | edit source]

In order to encode decimal number from 0 - 9 using Binary Coded Decimal Scheme , 10 4-bit-Binary-numbers are used

A B a3 a2 a1 a0 Decimal Number
0 0 0 0 0 0 0
0 1 0 0 0 1 1
1 0 0 0 1 0 2
1 1 0 0 1 1 3
1 1 0 1 0 0 4
1 1 0 1 0 1 5
1 1 0 1 1 0 6
1 1 0 1 1 1 7
1 1 1 0 0 0 8
1 1 1 0 0 1 9

ASCII Code[edit | edit source]

ASCII stands for American Standard Communication Information Interchange is the first standard introduced in North America for Information exchange . ASCII uses 7 bits Binary numbers to represent information in human language

  1. Number from 0 to 9
  2. Capital A to Z
  3. Common a to z


Code 0x20 (hexadecimal), the space character, denotes the space between words, as produced by the space-bar of a keyboard. The space character is considered an invisible graphic rather than a control character. Codes 0x21 to 0x7E, known as the printable characters, represent letters, digits, punctuation marks, and a few miscellaneous symbols.

Binary Oct Dec Hex Glyph
010 0000 040 32 20 space
010 0001 041 33 21 !
010 0010 042 34 22 "
010 0011 043 35 23 #
010 0100 044 36 24 $
010 0101 045 37 25 %
010 0110 046 38 26 &
010 0111 047 39 27 '
010 1000 050 40 28 (
010 1001 051 41 29 )
010 1010 052 42 2A *
010 1011 053 43 2B +
010 1100 054 44 2C ,
010 1101 055 45 2D -
010 1110 056 46 2E .
010 1111 057 47 2F /
011 0000 060 48 30 0
011 0001 061 49 31 1
011 0010 062 50 32 2
011 0011 063 51 33 3
011 0100 064 52 34 4
011 0101 065 53 35 5
011 0110 066 54 36 6
011 0111 067 55 37 7
011 1000 070 56 38 8
011 1001 071 57 39 9
011 1010 072 58 3A :
011 1011 073 59 3B ;
011 1100 074 60 3C <
011 1101 075 61 3D =
011 1110 076 62 3E >
011 1111 077 63 3F ?
Binary Oct Dec Hex Glyph
100 0000 100 64 40 @
100 0001 101 65 41 A
100 0010 102 66 42 B
100 0011 103 67 43 C
100 0100 104 68 44 D
100 0101 105 69 45 E
100 0110 106 70 46 F
100 0111 107 71 47 G
100 1000 110 72 48 H
100 1001 111 73 49 I
100 1010 112 74 4A J
100 1011 113 75 4B K
100 1100 114 76 4C L
100 1101 115 77 4D M
100 1110 116 78 4E N
100 1111 117 79 4F O
101 0000 120 80 50 P
101 0001 121 81 51 Q
101 0010 122 82 52 R
101 0011 123 83 53 S
101 0100 124 84 54 T
101 0101 125 85 55 U
101 0110 126 86 56 V
101 0111 127 87 57 W
101 1000 130 88 58 X
101 1001 131 89 59 Y
101 1010 132 90 5A Z
101 1011 133 91 5B [
101 1100 134 92 5C \
101 1101 135 93 5D ]
101 1110 136 94 5E ^
101 1111 137 95 5F _
Binary Oct Dec Hex Glyph
110 0000 140 96 60 `
110 0001 141 97 61 a
110 0010 142 98 62 b
110 0011 143 99 63 c
110 0100 144 100 64 d
110 0101 145 101 65 e
110 0110 146 102 66 f
110 0111 147 103 67 g
110 1000 150 104 68 h
110 1001 151 105 69 i
110 1010 152 106 6A j
110 1011 153 107 6B k
110 1100 154 108 6C l
110 1101 155 109 6D m
110 1110 156 110 6E n
110 1111 157 111 6F o
111 0000 160 112 70 p
111 0001 161 113 71 q
111 0010 162 114 72 r
111 0011 163 115 73 s
111 0100 164 116 74 t
111 0101 165 117 75 u
111 0110 166 118 76 v
111 0111 167 119 77 w
111 1000 170 120 78 x
111 1001 171 121 79 y
111 1010 172 122 7A z
111 1011 173 123 7B {
111 1100 174 124 7C |
111 1101 175 125 7D }
111 1110 176 126 7E ~

Reference[edit | edit source]



Data Selector

Data Selector[edit | edit source]

Data Selector take one data input and a number of selection inputs, and they have several outputs. They forward the data input to one of the outputs depending on the values of the selection inputs.

Demultiplexers are sometimes convenient for designing general purpose logic, because if the demultiplexer's input is always true, the demultiplexer acts as a decoder. This means that any function of the selection bits can be constructed by logically OR-ing the correct set of outputs.

Example: A Single Bit 1-to-4 Line Demultiplexer




ISO

ISO Standard[edit | edit source]

Template:Infobox Organization The International Organization for Standardization (Organisation internationale de normalisation), widely known as ISO (Template:Pron-en), is an international-standard-setting body composed of representatives from various national standards organizations. Founded on 23 February 1947, the organization promulgates worldwide proprietary industrial and commercial standards. It has its headquarters in Geneva, Switzerland.[1] While ISO defines itself as a non-governmental organization, its ability to set standards that often become law, either through treaties or national standards, makes it more powerful than most non-governmental organizations.[citation needed] In practice, ISO acts as a consortium with strong links to governments.[citation needed]

Name and abbreviation[edit | edit source]

The organization's logos in its two official languages, English and French, include the word ISO (Template:Pron-en), and it is usually referred to by this short-form name. ISO is not an acronym or initialism for the organization's full name in either official language. Rather, the organization adopted ISO based on the Greek word isos (ἴσος), meaning equal. Recognizing that the organization’s initials would be different in different languages, the organization's founders chose ISO as the universal short form of its name. This, in itself, reflects the aim of the organization: to equalize and standardize across cultures.[2][3]

International Standards and other publications[edit | edit source]

See also: List of ISO standards

ISO's main products are the International Standards. ISO also publishes Technical Reports, Technical Specifications, Publicly Available Specifications, Technical Corrigenda, and Guides.[4][5]

International Standards are identified in the format ISO[/IEC][/ASTM] [IS] nnnnn[:yyyy] Title, where nnnnn is the number of the standard, yyyy is the year published, and Title describes the subject. IEC for International Electrotechnical Commission is included if the standard results from the work of ISO/IEC JTC1 (the ISO/IEC Joint Technical Committee). ASTM (American Society for Testing and Materials)is used for standards developed in cooperation with ASTM International. The date and IS are not used for an incomplete or unpublished standard, and may under some circumstances be left off the title of a published work.

Technical Reports are issued when "a technical committee or subcommittee has collected data of a different kind from that which is normally published as an International Standard".[4] such as references and explanations. The naming conventions for these are the same as for standards, except TR prepended instead of IS in the report's name. Examples:

  • ISO/IEC TR 17799:2000 Code of Practice for Information Security Management
  • ISO/TR 19033:2000 Technical product documentation — Metadata for construction documentation

Technical Specifications can be produced when "the subject in question is still under development or where for any other reason there is the future but not immediate possibility of an agreement to publish an International Standard". Publicly Available Specifications may be "an intermediate specification, published prior to the development of a full International Standard, or, in IEC may be a 'dual logo' publication published in collaboration with an external organization".[4] Both are named by convention similar to Technical Reports, for example:

  • ISO/TS 16952-1:2006 Technical product documentation — Reference designation system — Part 1: General application rules
  • ISO/PAS 11154:2006 Road vehicles — Roof load carriers

ISO sometimes issues a Technical Corrigendum. These are amendments to existing standards because of minor technical flaws, usability improvements, or to extend applicability in a limited way. Generally, these are issued with the expectation that the affected standard will be updated or withdrawn at its next scheduled review.[4]

ISO Guides are meta-standards covering "matters related to international standardization".[4] They are named in the format "ISO[/IEC] Guide N:yyyy: Title", for example:

  • ISO/IEC Guide 2:2004 Standardization and related activities — General vocabulary
  • ISO/IEC Guide 65:1996 General requirements for bodies operating product certification

Standardization process[edit | edit source]

A standard published by ISO/IEC is the last stage of a long process that commonly starts with the proposal of new work within a committee. Here are some abbreviations used for marking a standard with its status:[6][7][8][9][10][11][12]

  • PWI - Preliminary Work Item
  • NP or NWIP - New Proposal / New Work Item Proposal (e.g. ISO/IEC NP 23007)
  • AWI - Approved new Work Item (e.g. ISO/IEC AWI 15444-14)
  • WD - Working Draft (e.g. ISO/IEC WD 27032)
  • CD - Committee Draft (e.g. ISO/IEC CD 23000-5)
  • FCD - Final Committee Draft (e.g. ISO/IEC FCD 23000-12)
  • DIS - Draft International Standard (e.g. ISO/IEC DIS 14297)
  • FDIS - Final Draft International Standard (e.g. ISO/IEC FDIS 27003)
  • PRF - Proof of a new International Standard (e.g. ISO/IEC PRF 18018)
  • IS - International Standard (e.g. ISO/IEC 13818-1:2007)

Abbreviations used for amendments:

  • NP Amd - New Proposal Amendment (e.g. ISO/IEC 15444-2:2004/NP Amd 3)
  • AWI Amd - Approved new Work Item Amendment (e.g. ISO/IEC 14492:2001/AWI Amd 4)
  • WD Amd - Working Draft Amendment (e.g. ISO 11092:1993/WD Amd 1)
  • CD Amd / PDAmd - Committee Draft Amendment / Proposed Draft Amendment (e.g. ISO/IEC 13818-1:2007/CD Amd 6)
  • FPDAmd / DAM (DAmd) - Final Proposed Draft Amendment / Draft Amendment (e.g. ISO/IEC 14496-14:2003/FPDAmd 1)
  • FDAM (FDAmd) - Final Draft Amendment (e.g. ISO/IEC 13818-1:2007/FDAmd 4)
  • PRF Amd - (e.g. ISO 12639:2004/PRF Amd 1)
  • Amd - Amendment (e.g. ISO/IEC 13818-1:2007/Amd 1:2007)

Other abbreviations:

  • TR - Technical Report (e.g. ISO/IEC TR 19791:2006)
  • DTR - Draft Technical Report (e.g. ISO/IEC DTR 19791)
  • TS - Technical Specification (e.g. ISO/TS 16949:2009)
  • DTS - Draft Technical Specification (e.g. ISO/DTS 11602-1)
  • TTA - Technology Trends Assessment (e.g. ISO/TTA 1:1994)
  • IWA - International Workshop Agreement (e.g. IWA 1:2005)
  • Cor - Technical Corrigendum (e.g. ISO/IEC 13818-1:2007/Cor 1:2008)

International Standards are developed by ISO technical committees (TC) and subcommittees (SC) by a process with six steps:[8][13]

  • Stage 1: Proposal stage
  • Stage 2: Preparatory stage
  • Stage 3: Committee stage
  • Stage 4: Enquiry stage
  • Stage 5: Approval stage
  • Stage 6: Publication stage

The TC/SC may set up working groups (WG) of experts for the preparation of a Working Drafts. Subcommittees may have several working groups, which can have several Sub Groups (SG).[14]

Stages in the development process of an ISO standard[7][8][9][12][13][15]
Stage code Stage Associated document name Abbreviations Description
00 Preliminary stage Preliminary work item PWI
10 Proposal stage New work item proposal NP or NWIP, NP Amd/TR/TS/IWA
20 Preparatory stage Working draft(s) AWI, AWI Amd/TR/TS, WD, WD Amd/TR/TS
30 Committee stage Committee draft(s) CD, CD Amd/Cor/TR/TS, PDAmd (PDAM), PDTR, PDTS
40 Enquiry stage Enquiry draft DIS, FCD, FPDAmd, DAmd (DAM), FPDISP, DTR, DTS (CDV in IEC)
50 Approval stage final draft International Standard FDIS, FDAmd (FDAM), PRF, PRF Amd/TTA/TR/TS/Suppl, FDTR
60 Publication stage International Standard ISO TR, TS, IWA, Amd, Cor
90 Review stage ISO TR, TS, IWA, Amd, Cor
95 Withdrawal stage

It is possible to omit certain stages, if there is a document with a certain degree of maturity at the start of a standardization project - for example a standard developed by another organization. ISO/IEC Directives allow also the so-called "Fast-track procedure". In this procedure a document is submitted directly for approval as a draft International Standard (DIS) to the ISO member bodies or as a final draft International Standard (FDIS) if the document was developed by an international standardizing body recognized by the ISO Council.[8]

The first step - a proposal of work (New Proposal) is approved at the relevant subcommittee or technical committee (e.g. SC29 and JTC1 respectively in the case of Moving Picture Experts Group - ISO/IEC JTC1/SC29/WG11). A working group (WG) of experts is set up by the TC/SC for the preparation of a Working Draft. When the scope of a new work is sufficiently clarified, some of the working groups (e.g. MPEG) usually make open request for proposals - known as "Call for proposals". The first document that is produced for example for audio and video coding standards is called a Verification Model (VM) (previously also called a Simulation and Test Model). When a sufficient confidence in the stability of the standard under development is reached, a Working Draft (WD) is produced. This is in the form of a standard but is kept internal to working group for revision. When a Working Draft is sufficiently solid and the working group is satisfied that it has developed the best technical solution to the problem being addressed, it becomes Committee Draft (CD). If it is required, it is then sent to the P-members of the TC/SC (National Bodies) for ballot. The CD becomes Final Committee Draft (FCD) if the number of positive votes is above the quorum. Successive committee drafts may be considered until consensus is reached on the technical content. When it is reached, the text is finalized for submission as a draft International Standard (DIS). The text is then submitted to National Bodies for voting and comment within a period of five months. It is approved for submission as a final draft International Standard (FDIS) if a two-thirds majority of the P-members of the TC/SC are in favour and not more than one-quarter of the total number of votes cast are negative. ISO will then hold a ballot with National Bodies where no technical changes are allowed (yes/no ballot), within a period of two months. It is approved as an International Standard (IS) if a two-thirds majority of the P-members of the TC/SC is in favour and not more than one-quarter of the total number of votes cast are negative. After approval, only minor editorial changes are introduced into the final text. The final text is sent to the ISO Central Secretariat which publishes it as the International Standard.[6][8]

ISO document copyright[edit | edit source]

ISO documents are copyrighted and ISO charges for copies of most. ISO does not, however, charge for most draft copies of documents in electronic format. Although useful, care must be taken using these drafts as there is the possibility of substantial change before it becomes finalized as a standard. Some standards by ISO and its official U.S. representative (and the International Electrotechnical Commission's via the U.S. National Committee) are made freely available.[16][17]

Members[edit | edit source]

A map of standards bodies who are ISO members
Key:
     members      correspondent members      subscriber members      other places with an ISO 3166-1 code who aren't members of ISO

ISO has 158 national members,[18] out of the 195 total countries in the world.

ISO has three membership categories:

  • Member bodies are national bodies that are considered to be the most representative standards body in each country. These are the only members of ISO that have voting rights.
  • Correspondent members are countries that do not have their own standards organization. These members are informed about ISO's work, but do not participate in standards promulgation.
  • Subscriber members are countries with small economies. They pay reduced membership fees, but can follow the development of standards.

Participating members are called "P" members as opposed to observing members which are called "O" members.

Products named after ISO[edit | edit source]

The fact that many of the ISO-created standards are ubiquitous has led, on occasion, to common use of "ISO" to describe the actual product that conforms to a standard. Some examples of this are:

  • CD images end in the file extension "ISO" to signify that they are using the ISO 9660 standard filesystem as opposed to another file system - hence CD images are commonly referred to as "ISOs". Virtually all computers with CD-ROM drives can read CDs that use this standard. Some DVD-ROMs also use ISO 9660 filesystems.
  • Photographic film's sensitivity to light, its "film speed," is described by ISO 5800:1987. Hence, the film's speed is often referred to as its "ISO number."

ISO/IEC Joint Technical Committee 1[edit | edit source]

Main page: ISO/IEC JTC1

To deal with the consequences of substantial overlap in areas of standardization and work related to information technology, ISO and IEC formed a Joint Technical Committee known as the ISO/IEC JTC1. It was the first such joint committee. The second joint committee was created in 2009 - Joint Project Committee - Energy efficiency and renewable energy sources - Common terminology (ISO/IEC/JTC 2).[19]

IWA document[edit | edit source]

Like ISO/TS, International Workshop Agreement (IWA) is another armoury of ISO for providing rapid response to requirements for standardization in areas where the technical structures and expertise are not currently in place. The utility harmonizes technical urgency industrial wide.

Criticism[edit | edit source]

With the exception of a small number of isolated standards,[20] ISO standards are normally not available free of charge, but for a purchase fee,[21] which has been seen by some as too expensive for small Open source projects.[22]

The ISO/IEC JTC1 fast-track procedures ("Fast-track" as used by OOXML and "PAS" as used by OpenDocument) have garnered criticism in relation to the standardization of Office Open XML (ISO/IEC 29500). Martin Bryan, outgoing Convenor of ISO/IEC JTC1/SC34 WG1, is quoted as saying:

I would recommend my successor that it is perhaps time to pass WG1’s outstanding standards over to OASIS, where they can get approval in less than a year and then do a PAS submission to ISO, which will get a lot more attention and be approved much faster than standards currently can be within WG1.

The disparity of rules for PAS, Fast-Track and ISO committee generated standards is fast making ISO a laughing stock in IT circles. The days of open standards development are fast disappearing. Instead we are getting 'standardization by corporation'.[23]

Computer security entrepreneur and Ubuntu investor, Mark Shuttleworth, commented on the Standardization of Office Open XML process by saying

I think it de-values the confidence people have in the standards setting process,

and Shuttleworth alleged that ISO did not carry out its responsibility. He also noted that Microsoft had intensely lobbied many countries that traditionally had not participated in ISO and stacked technical committees with Microsoft employees, solution providers and resellers sympathetic to Office Open XML.

When you have a process built on trust and when that trust is abused, ISO should halt the process ... ISO is an engineering old boys club and these things are boring so you have to have a lot of passion … then suddenly you have an investment of a lot of money and lobbying and you get artificial results. The process is not set up to deal with intensive corporate lobbying and so you end up with something being a standard that is not clear.[24]

See also[edit | edit source]

References[edit | edit source]

  1. "Discover ISO – Meet ISO". ISO. © 2007. http://www.iso.org/iso/about/discover-iso_meet-iso.htm. Retrieved 2007-09-07. 
  2. "ISO's name". ISO. 2007. http://www.iso.org/iso/en/networking/pr/isoname/isoname.html. Retrieved 2007-09-07. 
  3. "Discover ISO – ISO's name". ISO. 2007. http://www.iso.org/iso/about/discover-iso_meet-iso/discover-iso_isos-name.htm. Retrieved 2007-09-07. 
  4. a b c d e The ISO directives are published in two distinct parts:
    * "ISO Directives, Part 2: Rules for the structure and drafting of International Standards. 5th Edition" (pdf). ISO/IEC. 2004. Archived from the original on 2006-03-21. http://web.archive.org/web/20060321203237/http://www.iec.ch/tiss/iec/Directives-Part2-Ed5.pdf. Retrieved 2007-09-07. 
  5. ISO. "ISO/IEC Directives and ISO supplement". http://www.iso.org/directives. Retrieved 2010-01-01. 
  6. a b "About MPEG". chiariglione.org. http://www.chiariglione.org/mpeg/about_mpeg.htm. Retrieved 2009-12-13. 
  7. a b ISO. "International harmonized stage codes". http://www.iso.org/iso/standards_development/processes_and_procedures/stages_description/stages_table.htm#s90. Retrieved 2009-12-31. 
  8. a b c d e ISO. "Stages of the development of International Standards". http://www.iso.org/iso/standards_development/processes_and_procedures/stages_description.htm. Retrieved 2009-12-31. 
  9. a b "The ISO27k FAQ - ISO/IEC acronyms and committees". IsecT Ltd.. http://www.iso27001security.com/html/faq.html#Acronyms. Retrieved 2009-12-31. 
  10. ISO (2007). "ISO/IEC Directives Supplement — Procedures specific to ISO" (PDF). http://www.astm.org/COMMIT/1st_Supplement.pdf. Retrieved 2009-12-31. 
  11. ISO (2007). "List of abbreviations used throughout ISO Online". http://www.iso.org/iso/support/faqs/faqs_list_abbreviations.htm. Retrieved 2009-12-31. 
  12. a b "US TAG COMMITTEE HANDBOOK" (DOC). 2008-03. http://www.sae.org/exdomains/standardsdev/global_resources/US%20TAG%20Committe%20Handbook%206March2008.doc. Retrieved 2010-01-01. 
  13. a b ISO (2008) (PDF), ISO/IEC Directives, Part 1 - Procedures for the technical work, Sixth edition, 2008, archived from the original on 2010-07-14, http://web.archive.org/web/20100714140207/http://www.iec.ch/tiss/iec/Directives-Part1-Ed6.pdf, retrieved 2010-01-01 
  14. ISO, IEC (2009-11-05). "ISO/IEC JTC 1/SC 29, SC 29/WG 11 Structure (ISO/IEC JTC 1/SC 29/WG 11 - Coding of Moving Pictures and Audio)". http://www.itscj.ipsj.or.jp/sc29/29w12911.htm. Retrieved 2009-11-07. 
  15. ISO/IEC JTC1 (2009-11-02), Letter Ballot on the JTC 1 Standing Document on Technical Specifications and Technical Reports, http://isotc.iso.org/livelink/livelink/JTC001-N-9876.pdf?func=doc.Fetch&nodeId=8498789&docTitle=JTC001-N-9876, retrieved 2010-01-01 
  16. "Freely Available ISO Standards". ISO. Last updated 2007-08-08. http://isotc.iso.org/livelink/livelink/fetch/2000/2489/Ittf_Home/PubliclyAvailableStandards.htm. Retrieved 2007-09-07. 
  17. "Free ANSI Standards". http://webstore.ansi.org/ansidocstore/free_standards.asp. Retrieved 2007-06-19. 
  18. "General information on ISO". ISO. © 2009. http://www.iso.org/iso/support/faqs/faqs_general_information_on_iso.htm. Retrieved 2009-01-29. 
  19. "ISO/IEC/JTC 2 - Joint Project Committee - Energy efficiency and renewable energy sources - Common terminology". http://www.iso.org/iso/standards_development/technical_committees/list_of_iso_technical_committees/iso_technical_committee.htm?commid=585141. Retrieved 2010-01-01. 
  20. "Freely Available Standards". ISO. http://standards.iso.org/ittf/PubliclyAvailableStandards/index.html. Retrieved 2008-04-26. 
  21. "Shopping FAQs". ISO. http://www.iso.org/iso/store/shopping_faqs.htm. Retrieved 2008-04-26. 
  22. Jelliffe, Rick (2007-08-01). "Where to get ISO Standards on the Internet free". oreillynet.com. http://www.oreillynet.com/xml/blog/2007/08/where_to_get_iso_standards_on.html. Retrieved 2008-04-26. "The lack of free online availability has effectively made ISO standard irrelevant to the (home/hacker section of the) Open Source community" 
  23. "Report on WG1 activity for December 2007 Meeting of ISO/IEC JTC1/SC34/WG1 in Kyoto". iso/jtc1 sc34. 2007-11-29. http://www.jtc1sc34.org/repository/0940.htm. 
  24. "Ubuntu’s Shuttleworth blames ISO for OOXML’s win". ZDNet.com. 2008-04-01. http://blogs.zdnet.com/open-source/?p=2222. 

External links[edit | edit source]

Reference[edit | edit source]