DOCSLIB.ORG

A Technical Guide to Computer-Communications Interface Standards

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text

Load more

\ co NBS \ J TECHNICAL NOTE 843 * Vau o* NATIONAL BUREAU OF STANDARDS 1 The National Bureau of Standards was established by an act of Congress March 3, 1901. The Bureau's overall goal is to strengthen and advance the Nation's science and technology and facilitate their effective application for public benefit. To this end, the Bureau conducts research and provides: (1) a basis for the Nation's physical measurement system, (2) scientific and technological services for industry and government, (3) a technical basis for equity in trade, and (4) technical services to promote public safety. The Bureau consists of the Institute for Basic Standards, the Institute for Materials Research, the Institute for Applied Technology, the Institute for Computer Sciences and Technology, and the Office for Information Programs. THE INSTITUTE FOR BASIC STANDARDS provides the central basis within the United States of a complete and consistent system of physical measurement; coordinates that system with measurement systems of other nations; and furnishes essential services leading to accurate and uniform physical measurements throughout the Nation's scientific community, industry, and commerce. The Institute consists of a Center for Radiation Research, an Office of Meas- urement Services and the following divisions: Applied Mathematics — Electricity — Mechanics — Heat — Optical Physics — Nuclear Sciences 2 — Applied Radiation 2 — Quantum Electronics * — Electromagnetics * — Time 3 and Frequency — Laboratory Astrophysics — Cryogenics *. THE INSTITUTE FOR MATERIALS RESEARCH conducts materials research leading to improved methods of measurement, standards, and data on the properties of well-characterized materials needed by industry, commerce, educational institutions, and Government; provides advisory and research services to other Government agencies; and develops, produces, and distributes standard reference materials. The Institute consists of the Office of Standard Reference Materials and the following divisions: Analytical Chemistry — Polymers — Metallurgy — Inorganic Materials — Reactor Radiation — Physical Chemistry. THE INSTITUTE FOR APPLIED TECHNOLOGY provides technical services to promote the use of available technology and to facilitate technological innovation in industry and Government; cooperates with public and private organizations leading to the development of technological standards (including mandatory safety standards), codes and methods of test; and provides technical advice and services to Government agencies upon request. The Institute consists of a Center for Building Technology and the following divisions and offices: Engineering and Product Standards — Weights and Measures — Invention and Innova- tion — Product Evaluation Technology — Electronic Technology — Technical Analysis — Measurement Engineering — Structures, Materials, and Life Safety ' — Building Environment' — Technical Evaluation and Application* — Fire Technology. THE INSTITUTE FOR COMPUTER SCIENCES AND TECHNOLOGY conducts research and provides technical services designed to aid Government agencies in improving cost effec- tiveness in the conduct of their programs through the selection, acquisition, and effective utilization of automatic data processing equipment; and serves as the principal focus within the executive branch for the development of Federal standards for automatic data processing equipment, techniques, and computer languages. The Institute consists of the following divisions: Computer Services — Systems and Software — Computer Systems Engineering — Informa- tion Technology. THE OFFICE FOR INFORMATION PROGRAMS promotes optimum dissemination and accessibility of scientific information generated within NBS and other agencies of the Federal Government; promotes the development of the National Standard Reference Data System and a system of information analysis centers dealing with the broader aspects of the National Measurement System; provides appropriate services to ensure that the NBS staff has optimum accessibility to the scientific information of the world. The Office consists of the following organizational units: Office of Standard Reference Data — Office of Information Activities — Office of Technical Publications — Library — Office of International Relations. •Headquarters and Laboratories at Galthersburg, Maryland, unless otherwise noted; mailing address Washington, D.C. 20234. 1 Part of the Center for Radiation Research. * ' Located at Boulder, Colorado 80302. Part of the Center for Building Technology. NOV 1 1974 i\jyh cul(L - S&r $6100 tf*753 A Technical Guide to Computer-Communications Interface Standards Albrecht J. Neumann, Brian G. Lucas, Justin C. Walker, and Dennis W. Fife Systems and Software Division Institute for Computer Sciences and Technology National Bureau of Standards Washington, D.C. 20234 t.„- rea-UwAaaJD no-Te no. ^3 Sponsored by: Joint Technical Support Activity Defense Communications Agency Washington, D.C. 20305 f? ''I*** '"Vauo**" U.S. DEPARTMENT OF COMMERCE, Frederick B. Dent, Secretary NATIONAL BUREAU OF STANDARDS, Richard W. Roberts, Director Issued August 1974 Library of Congress Catalog Card Number: 74-600131 National Bureau of Standards Technical Note 843 Nat. Bur. Stand. (U.S.), Tech. Note 843, 111 pages (Aug. 1974) CODEN: NBTNAE U.S. GOVERNMENT PRINTING OFFICE WASHINGTON: 1974 For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402 (Order by SD Catalog No. 03.46:843). Price $1 .50 ACKNOWLEDGMENT The authors are indebted to George Clark, Jack Little, and Ray Moore of the Computer Systems Engineering Division, NBS, who contributed their expertise as experienced participants in data communications standards to a constructive review of this report. Xll CONTENTS Page 1. Introduction 1 1.1 Purpose* 1 1.2 Scope 1 1.3 Sources of Standards 2 1.4 Overview 3 1.5 References 3 2. DTE-DCE, Interfaces 4 2.1 DTE-Modem Interface 4 2.2 DTE-ACE Interface 11 2.3 Signal Quality at the Interface Between DTE and DCE . 15 2.4 Standard Signalling Rates 20 2.5 ItLlitary Subsystem Interface Standards 21 2.6 Conclusions 23 2.7 Standards 23 3. User Terminal Standards 26 3.1 International Standards for Character Codes 26 3.2 National Standards for Character Codes 26 3.3 Implementation of the 7-bit Code 26 3.4 Structure of the 7-bit Code 28 3.5 Subsets of the 7-bit Code 37 3.6 Code Extension and Expansion 37 3.7 Keyboards 47 3.8 References 59 4. Link Control Procedures 63 4.1 Links: Configuration and Control 63 4.2 Character-oriented Procedures 68 4.3 Bit-Oriented Procedures 83 4.4 References 94 5. Glossary of Terms 97 IV FIGURES Page 2-1 DTE-DCE Interface, Non-Military 6 2-2 Interchange Circuits [RS-232-C] 7 2-3 Control Circuit Actions [RS-232-C] 8 2-4 Standard Interface Types [RS-232-C] 12 2-5 Interface Types for Data Transmission Configuration [RS-232-C] 13 2-6 Standard Automatic Call Equipment Interfaces [RS-366] 14 2-7 Signal Quality Criteria, Synchronous DCE Interface [RS-334] 17 2-8 Start-Stop Signal Nomenclature 19 2-9 Typical Digital Communication Control Equipment Interfaces [MIL STD 188-347] 22 3-1 ASCII Code Table 30 3-2 Structure of the 7-bit Code Table 31 3-3 Standard Graphical Representation of Control Characters 36 3-4 8-bit Code Table 39 3-5 A Proposed Set of Extended Control Characters 40 3-6 Legal Characters in Escape Sequences 42 3-7 Keyboard Arrangement Nbtational System 49 3-8 Type I, Class 1 Standard Keyboard Arrangement 50 3-9 Type I, Class 2 Standard Keyboard Arrangement 51 3-10 Type II, Class 1 Standard Keyboard Arrangement 52 3-11 Three Row Communication Keyboard (Interim Standard) 53 3-12 Three Row Weather Keyboard (Interim Standard) 53 3-13 Logical Bit Pairing Keyboard Arrangement 55 3-14 Typewriter Pairing Keyboard Arrangement 56 3-15 Physical Arrangement of Numerical Keys 57 4-1 The Model Link 64 4-2 Two-way Alternate Terminal, Two-way Simultaneous Sublink(s) 65 4-3 Message Formats 71 4-4 Phases of Transmission 74 4-5 Link Level Message Format 82 4-6 Primary/Primary Link 84 4-7 Primary/ Secondary Link 84 4-8 ADCCP Frame 85 TABLES Page 3-1 Standards for character codes 27 3-2 Standards for representation of characters on physical media 28 3-3 Standards for representation of characters during data trans- mission 28 3-4 Standards for graphical representation of control characters 35 3-5 Standards that specify subsets of the 7-bit character code 37 3-6 Standards relating to code extension and expansion 39 3-7 Use of escape sequences 43 3-8 De facto conventions for two character private escape sequences 47 3-9 Code extension in a 7-bit code 48 3-10 Code extension in an 8-bit code 48 3-11 Control code assignments 58 4-1 Applicable standards 68 4-2 ASCII Communications control characters 71 4-3 Control procedure matrix 73 4-4 BSC communications control characters from the EBCDIC character set 80 4-5 Secondary state-variables and parameters 87 4-6 ADCCP Commands and Responses 90 4-7 Classes of Procedures 91 VI A TECHNICAL GUIDE TO COMPUTER-COMMUNICATIONS INTERFACE STANDARDS Albrecht J. Neumann, Brian G. Lucas, Justin C. Walker, Dennis W. Fife A technical summary and guide is given for existing and forthcoming Federal and national standards on data communications pertinent to computer networking. Selected international standards and industry practices are included for completeness. Prepared to assist the applica- tion of standards within the World Wide Military Command and Control System, this handbook should be useful to all ADP system designers interested in uniform
Recommended publications
  • 16-Channel DAS with 16-Bit, Bipolar Input, Dual Simultaneous Sampling

    16-Channel DAS with 16-Bit, Bipolar Input, Dual Simultaneous Sampling

    16-Channel DAS with 16-Bit, Bipolar Input, Dual Simultaneous Sampling ADC Data Sheet AD7616 FEATURES APPLICATIONS 16-channel, dual, simultaneously sampled inputs Power line monitoring Independently selectable channel input ranges Protective relays True bipolar: ±10 V, ±5 V, ±2.5 V Multiphase motor control Single 5 V analog supply and 2.3 V to 3.6 V VDRIVE supply Instrumentation and control systems Fully integrated data acquisition solution Data acquisition systems (DASs) Analog input clamp protection GENERAL DESCRIPTION Input buffer with 1 MΩ analog input impedance First-order antialiasing analog filter The AD7616 is a 16-bit, DAS that supports dual simultaneous On-chip accurate reference and reference buffer sampling of 16 channels. The AD7616 operates from a single 5 V Dual 16-bit successive approximation register (SAR) ADC supply and can accommodate ±10 V, ±5 V, and ±2.5 V true bipolar Throughput rate: 2 × 1 MSPS input signals while sampling at throughput rates up to 1 MSPS Oversampling capability with digital filter per channel pair with 90.5 dB SNR. Higher SNR performance can Flexible sequencer with burst mode be achieved with the on-chip oversampling mode (92 dB for an Flexible parallel/serial interface oversampling ratio (OSR) of 2). SPI/QSPI/MICROWIRE/DSP compatible The input clamp protection circuitry can tolerate voltages up to Optional cyclic redundancy check (CRC) error checking ±21 V. T h e AD7616 has 1 MΩ analog input impedance, regardless Hardware/software configuration of sampling frequency. The single-supply operation, on-chip Performance filtering, and high input impedance eliminate the need for 92 dB SNR at 500 kSPS (2× oversampling) driver op amps and external bipolar supplies.
  • The CLASP Application Security Process

    The CLASP Application Security Process

    The CLASP Application Security Process Secure Software, Inc. Copyright (c) 2005, Secure Software, Inc. The CLASP Application Security Process The CLASP Application Security Process TABLE OF CONTENTS CHAPTER 1 Introduction 1 CLASP Status 4 An Activity-Centric Approach 4 The CLASP Implementation Guide 5 The Root-Cause Database 6 Supporting Material 7 CHAPTER 2 Implementation Guide 9 The CLASP Activities 11 Institute security awareness program 11 Monitor security metrics 12 Specify operational environment 13 Identify global security policy 14 Identify resources and trust boundaries 15 Identify user roles and resource capabilities 16 Document security-relevant requirements 17 Detail misuse cases 18 Identify attack surface 19 Apply security principles to design 20 Research and assess security posture of technology solutions 21 Annotate class designs with security properties 22 Specify database security configuration 23 Perform security analysis of system requirements and design (threat modeling) 24 Integrate security analysis into source management process 25 Implement interface contracts 26 Implement and elaborate resource policies and security technologies 27 Address reported security issues 28 Perform source-level security review 29 Identify, implement and perform security tests 30 The CLASP Application Security Process i Verify security attributes of resources 31 Perform code signing 32 Build operational security guide 33 Manage security issue disclosure process 34 Developing a Process Engineering Plan 35 Business objectives 35 Process
  • IS 13737 (1993): Isoinformation Technology

    IS 13737 (1993): Isoinformation Technology

    इंटरनेट मानक Disclosure to Promote the Right To Information Whereas the Parliament of India has set out to provide a practical regime of right to information for citizens to secure access to information under the control of public authorities, in order to promote transparency and accountability in the working of every public authority, and whereas the attached publication of the Bureau of Indian Standards is of particular interest to the public, particularly disadvantaged communities and those engaged in the pursuit of education and knowledge, the attached public safety standard is made available to promote the timely dissemination of this information in an accurate manner to the public. “जान का अधकार, जी का अधकार” “परा को छोड न 5 तरफ” Mazdoor Kisan Shakti Sangathan Jawaharlal Nehru “The Right to Information, The Right to Live” “Step Out From the Old to the New” IS 13737 (1993): ISOInformation Technology - 130 mm Rewritable optical disk cartridges for information interchange [LITD 16: Computer Hardware, Peripherals and Identification Cards] “ान $ एक न भारत का नमण” Satyanarayan Gangaram Pitroda “Invent a New India Using Knowledge” “ान एक ऐसा खजाना > जो कभी चराया नह जा सकताह ै”ै Bhartṛhari—Nītiśatakam “Knowledge is such a treasure which cannot be stolen” IS 13737 : 1993 ISO/IEC 10089 : 1991 CONTENTS Page NationalForeword..........,..........................................‘.““““’ . (vii) 1 Scope 1 2 Conformance 1 3 Normative references 1 4 Conventions and notations 1 5 List of acronyms 2 6 Definitions 2 2 6. I case 2 6.2 Clamping Zone 6.3
  • 1. Background This Paper Is About a Method for Recovering Data from Floppy Disks That Are Failing Due to “Weak Bits”

    1. Background This Paper Is About a Method for Recovering Data from Floppy Disks That Are Failing Due to “Weak Bits”

    A Method for Recovering Data From Failing Floppy Disks with a Practical Example Dr. Frederick B. Cohen, Ph.D. and Charles M. Preston Fred Cohen & Associates and California Sciences Institute Abstract: As floppy disks and other similar media age, they have a tendency to lose data because of the reduction in retention of electromagnetic fields over time associated with various environmental degradation factors. In attempting to read these disks, the coding techniques used to write them can be exploited along with the proposed fault mechanisms to demonstrate that repetitions of read attempts under proper conditions yield valid data subject to specific error modes. In many cases those errors can be partially or completely reversed by analysis of read results. A practical example involving a case of substantial legal value is used as an example of the application of these methods. Keywords: weak bits, floppy disks, digital forensics, coding, field density loss, the birthday problem, error inversion 1. Background This paper is about a method for recovering data from floppy disks that are failing due to “weak bits”. It describes a repetitive read technique that has successfully recovered data from failing floppy disks in forensic cases and describes analysis of the results of such repetitive reads in terms of yielding forensically sound data values. These techniques are not new or particularly unique; however, they are not widely published and analysis necessary to support their use in legal matters has not been found elsewhere. The particular matter used as an example in this analysis involved a floppy disk that was more than 15 years old and that contained the only copy of a binary assembled version of a software program that was subject to intellectual property claims of sufficient value to warrant recovery beyond the means normally used by commercial recovery firms.
  • ISO/IEC JTC1/SC2/WG2 N 2005 Date: 1999-05-29

    ISO/IEC JTC1/SC2/WG2 N 2005 Date: 1999-05-29

    ISO INTERNATIONAL ORGANIZATION FOR STANDARDIZATION ORGANISATION INTERNATIONALE DE NORMALISATION --------------------------------------------------------------------------------------- ISO/IEC JTC1/SC2/WG2 Universal Multiple-Octet Coded Character Set (UCS) -------------------------------------------------------------------------------- ISO/IEC JTC1/SC2/WG2 N 2005 Date: 1999-05-29 TITLE: ISO/IEC 10646-1 Second Edition text, Draft 2 SOURCE: Bruce Paterson, project editor STATUS: Working paper of JTC1/SC2/WG2 ACTION: For review and comment by WG2 DISTRIBUTION: Members of JTC1/SC2/WG2 1. Scope This paper provides a second draft of the text sections of the Second Edition of ISO/IEC 10646-1. It replaces the previous paper WG2 N 1796 (1998-06-01). This draft text includes: - Clauses 1 to 27 (replacing the previous clauses 1 to 26), - Annexes A to R (replacing the previous Annexes A to T), and is attached here as “Draft 2 for ISO/IEC 10646-1 : 1999” (pages ii & 1 to 77). Published and Draft Amendments up to Amd.31 (Tibetan extended), Technical Corrigenda nos. 1, 2, and 3, and editorial corrigenda approved by WG2 up to 1999-03-15, have been applied to the text. The draft does not include: - character glyph tables and name tables (these will be provided in a separate WG2 document from AFII), - the alphabetically sorted list of character names in Annex E (now Annex G), - markings to show the differences from the previous draft. A separate WG2 paper will give the editorial corrigenda applied to this text since N 1796. The editorial corrigenda are as agreed at WG2 meetings #34 to #36. Editorial corrigenda applicable to the character glyph tables and name tables, as listed in N1796 pages 2 to 5, have already been applied to the draft character tables prepared by AFII.
  • Floppy Disc Controller Instruction Manual

    Floppy Disc Controller Instruction Manual

    Part Number 2120-0067 OQ419 FLOPPY DISC CONTROLLER INSTRUCTION MANUAL March 1985 DISTRIBUTED LOGIC CORPORATION 1555 S. Sinclair Street P.O. Box 6270 ~R Anaheim, California 92806 I nmmI Telephone: (714) 937·5700 Telex: 6836051 Contents SECTION 1 - GENERAL INFORMATION 1.1 INTRODUCTION 1 1.2 GENERAL DESCRIPTION 2 1.3 COMPATIBILITY 2 1.4 LOGICAL TRACK FORMAT 3 1.4.1 Sector Header Field 3 1.4.2 Data Field 5 1.4.3 CRC - Cyclic Redundancy Check 5 1.5 RECORDING SCHEME 6 1.6 SPECIFICATIONS 6 SECTION 2 - INSTALLATION 2.1 CONTROLLER JUMPER CONFIGURATIONS 7 2.1.1 Device and Vector Address Selection 8 2.1.2 Device Interrupt Priority 9 2.1.3 Bootstrap 10 2.1.4 Wri te Precompensati on 10 2.1.5 Write Current Control 11 2.1.6 Drive Step Rate 11 2.2 DRIVE CONFIGURATIONS 11 2.3 CABLING 19 2.4 CONTROLLER INSTALLATION 21 2.5 INITIAL CHECKOUT 21 SECTION 3 - OPERATION 3.1 GENERAL INFORHATION 23 3.2 BOOTSTRAPPING 23 3.3 FORMATTING 24 3.4 FILL/WRITE OPERATION 25 3.5 READ/EMPTY OPERATION 27 3.6 OPERATION USING RT-ll 27 SECTION 4 - PROGRAMMING 4.1 GENERAL INFORMATION 29 4.2 COMMAND AND STATUS REGISTER - RXVCS (177170) 30 4.3 DATA BUFFER (177172) 31 4.3.1 Data Buffer Register (RXVDB) 32 4.3.2 Trace Address Register (RXVTA) 32 4.3.3 Sector Address Register (RXVSA) 32 4.3.4 Word Count Register (RXVWC) 32 4.3.5 Bus Address Register (RXVBA) 33 4.3.6 Error and Status Register (RXVES) 33 4.3.7 Bus Address Extension Register (RXVBAE) 35 i i ; 4.4 EXTENDED STATUS REGISTERS 35 4.5 COMMAND PROTOCOL 36 4.5.1 Fill Buffer (000) 36 4.5.2 Empty Buffer (001) 37 4.5.3 Write Buffer
  • High Performance Table-Based Algorithm for Pipelined CRC Calculation

    High Performance Table-Based Algorithm for Pipelined CRC Calculation

    High Performance Table-Based Algorithm for Pipelined CRC Calculation Yan Sun and Min Sik Kim School of Electrical Engineering and Computer Science Washington State University Pullman, Washington 99164-2752, U.S.A. Email: fysun,[email protected] Abstract—In this paper, we present a fast cyclic redun- for message length detection of variable-length message dancy check (CRC) algorithm that performs CRC compu- communications [4], [5]. tation for an arbitrary length of message in parallel. For a Communication networks use protocols with ever in- given message with any length, the algorithm first chunks the message into blocks, each of which has a fixed size equal creasing demands on speed. The increasing performance to the degree of the generator polynomial. Then it computes needs can be fulfilled by using ASICs (Application Spe- CRC for the chunked blocks in parallel using lookup tables, cific Integrated Circuits) and this will probably also be and the results are combined together with XOR operations. the case in the future. Meeting the speed requirement In the traditional implementation, it is the feedback that is crucial because packets will be dropped if processing makes pipelining problematic. In the proposed algorithm, we solve this problem by taking advantage of CRC’s properties is not completed at wire speed. Recently, protocols for and pipelining the feedback loop. The short pipeline latency high throughput have emerged, such as IEEE 802.11n of our algorithm enables a faster clock frequency than WLAN and UWB (Ultra Wide Band), and new protocols previous approaches, and it also allows easy scaling of the with even higher throughput requirement are on the way.
  • A Method for Recovering Data from Failing Floppy Disk Drives

    A Method for Recovering Data from Failing Floppy Disk Drives

    A Method for Recovering Data From Failing Floppy Disk Drives Dr. Frederick B. Cohen, Ph.D. and Charles Preston Background: This paper is about a method for recovering data from floppy disks that are failing due to weak bits. It describes a repetitive read technique that has successfully recovered data from failing floppies in forensic cases and describes other related techniques. None of these techniques are new or particularly unique, however, they are not widely published to the best of the authors knowledge and some of the related analysis may be helpful in making more definitive determinations in some cases. The nature of 'weak' bits and failure modes: Floppy disks tend to degrade in various ways over time and under various environmental conditions such as temperature, humidity, and so forth. In some cases this results in the presence of so-called “weak” bits on the media. Weak bits are bits that are sufficiently degraded in their electromagnetic field so as to yield voltages between the values for a '1' and a '0' when read by the read heads on most floppy disks. This is a result of reduced flux density in the electromagnetic media. In particular, the floppy disk coding used in most current disks is identified in: http://cma.zdnet.com/book/upgraderepair/ch14/ch14.htm as Modified Frequency Modulation (MFM) which uses timed flux density transitions to indicate bits. In particular, it uses a “No transition, Transition” (NT) sequence to indicate a “1”, a TN to indicate a '0' preceded by a '0', and an NN to indicate a '0' preceded by a '1'.
  • Acronyms Appendix

    Acronyms Appendix

    APPENDIX A Acronyms Table A-1 defines the acronyms that are used in this publication. Ta b l e A- 1 L i s t o f Ac ro ny m s Acronym Expansion AAL ATM adaptation layer ACE access control entry ACL access control list ACNS Application and Content Networking System AFI authority and format identifier Agport aggregation port ALPS Airline Protocol Support AMP Active Monitor Present APaRT Automated Packet Recognition and Translation ARP Address Resolution Protocol ATA Analog Telephone Adaptor ATM Asynchronous Transfer Mode AV attribute value BDD binary decision diagrams BECN backward explicit congestion notification BGP Border Gateway Protocol Bidir bidirectional PIM BPDU bridge protocol data unit BRF bridge relay function BSC Bisync BSTUN Block Serial Tunnel BUS broadcast and unknown server BVI bridge-group virtual interface CAM content-addressable memory CAR committed access rate Catalyst 6500 Series Switch Content Switching Module with SSL Command Reference OL-6237-01 A-1 Appendix A Acronyms Table A-1 List of Acronyms (continued) Acronym Expansion CBAC context based access control CCA circuit card assembly CDP Cisco Discovery Protocol CEF Cisco Express Forwarding CHAP Challenge Handshake Authentication Protocol CIR committed information rate CIST Common and Internal Spanning Tree CLI command-line interface CLNS Connection-Less Network Service CMNS Connection-Mode Network Service CNS Cisco Networking Services COPS Common Open Policy Server COPS-DS Common Open Policy Server Differentiated Services CoS class of service CPLD Complex Programmable
  • Programming Embedded Systems, Second Edition with C and GNU Development Tools

    Programming Embedded Systems, Second Edition with C and GNU Development Tools

    Programming Embedded Systems Second Edition Programming Embedded Systems, Second Edition with C and GNU Development Tools Foreword If you mention the word embedded to most people, they'll assume you're talking about reporters in a war zone. Few dictionaries—including the canonical Oxford English Dictionary—link embedded to computer systems. Yet embedded systems underlie nearly all of the electronic devices used today, from cell phones to garage door openers to medical instruments. By now, it's nearly impossible to build anything electronic without adding at least a small microprocessor and associated software. Vendors produce some nine billion microprocessors every year. Perhaps 100 or 150 million of those go into PCs. That's only about one percent of the units shipped. The other 99 percent go into embedded systems; clearly, this stealth business represents the very fabric of our highly technological society. And use of these technologies will only increase. Solutions to looming environmental problems will surely rest on the smarter use of resources enabled by embedded systems. One only has to look at the network of 32-bit processors in Toyota's hybrid Prius to get a glimpse of the future. Page 1 Programming Embedded Systems Second Edition Though prognostications are difficult, it is absolutely clear that consumers will continue to demand ever- brainier products requiring more microprocessors and huge increases in the corresponding software. Estimates suggest that the firmware content of most products doubles every 10 to 24 months. While the demand for more code is increasing, our productivity rates creep up only slowly. So it's also clear that the industry will need more embedded systems people in order to meet the demand.
  • High Rate Ultra Wideband PHY and MAC Standard ECMA-368

    High Rate Ultra Wideband PHY and MAC Standard ECMA-368

    ECMA-368 1st Edition / December 2005 High Rate Ultra Wideband PHY and MAC Standard Standard ECMA-368 1st Edition - December 2005 High Rate Ultra Wideband PHY and MAC Standard Ecma International Rue du Rhône 114 CH-1204 Geneva T/F: +41 22 849 6000/01 www.ecma-international.org Introduction This Ecma Standard specifies the ultra wideband (UWB) physical layer (PHY) and medium access control (MAC) sublayer for a high-speed short range wireless network, utilizing all or part of the spectrum between 3 100 − 10 600 MHz supporting data rates of up to 480 Mb/s. This standard divides the spectrum into 14 bands, each with a bandwidth of 528 MHz. The first 12 bands are then grouped into 4 band groups consisting of 3 bands, and the last two bands are grouped into a fifth band group. A MultiBand Orthogonal Frequency Division Modulation (MB-OFDM) scheme is used to transmit information. A total of 110 sub-carriers (100 data carriers and 10 guard carriers) are used per band. In addition, 12 pilot subcarriers allow for coherent detection. Frequency-domain spreading, time-domain spreading, and forward error correction (FEC) coding are provided for optimum performance under a variety of channel conditions. The MAC sublayer is designed to enable mobility, such that a group of devices may continue communicating while merging or splitting from other groups of devices. To maximize flexibility, the functionality of this MAC is distributed among devices. These functions include distributed coordination to avoid interference between different groups of devices by appropriate use of channels and distributed medium reservations to ensure Quality of Service.
  • Control Characters in ASCII and Unicode

    Control Characters in ASCII and Unicode

    Control characters in ASCII and Unicode Tens of odd control characters appear in ASCII charts. The same characters have found their way to Unicode as well. CR, LF, ESC, CAN... what are all these codes for? Should I care about them? This is an in-depth look into control characters in ASCII and its descendants, including Unicode, ANSI and ISO standards. When ASCII first appeared in the 1960s, control characters were an essential part of the new character set. Since then, many new character sets and standards have been published. Computing is not the same either. What happened to the control characters? Are they still used and if yes, for what? This article looks back at the history of character sets while keeping an eye on modern use. The information is based on a number of standards released by ANSI, ISO, ECMA and The Unicode Consortium, as well as industry practice. In many cases, the standards define one use for a character, but common practice is different. Some characters are used contrary to the standards. In addition, certain characters were originally defined in an ambiguous or loose way, which has resulted in confusion in their use. Contents Groups of control characters Control characters in standards o ASCII control characters o C1 control characters o ISO 8859 special characters NBSP and SHY o Control characters in Unicode Control characters in modern applications Character list o ASCII o C1 o ISO 8859 Categories Translations Character index Sources This article starts by looking at the history of control characters in standards. We then move to modern times.