Glossary of Computer Software Development Terminology

The terms are defined, as much as possible, using available standards. The source of such definitions appears immediately following the term or phrase in parenthesis, e.g. (NIST).

The source documents are listed at the bottom of this page.

NBS. National Bureau of Standards.

NIST. National Institute for Standards and Technology.

NMI. non-maskable interrupt.

NMOS. n-channel MOS.

National Bureau of Standards. Now National Institute for Standards and Technology.

National Institute for Standards and Technology. Gaithersburg, MD 20899. A federal agency under the Department of Commerce, originally established by an act of Congress on March 3, 1901 as the National Bureau of Standards. The Institute's overall goal is to strengthen and advance the Nation's science and technology and facilitate their effective application for public benefit. The National Computer Systems Laboratory conducts research and provides, among other things, the technical foundation for computer related policies of the Federal Government.

n-channel MOS. A type of microelectronic circuit used for logic and memory chips.

network. (1) (ISO) An arrangement of nodes and interconnecting branches. (2) A system [transmission channels and supporting hardware and software] that connects several remotely located computers via telecommunications.

network database. A database organization method that allows for data relationships in a net-like form. A single data element can point to multiple data elements and can itself be pointed to by other data elements. Contrast with relational database.

nibble. Half a byte, or four bits.

node. A junction or connection point in a network, e.g. a terminal or a computer.

noncritical code analysis. (IEEE) (1) Examines software elements that are not designated safety-critical and ensures that these elements do not cause a hazard. (2) Examines portions of the code that are not considered safety-critical code to ensure they do not cause hazards. Generally, safety-critical code should be isolated from non-safety-critical code. This analysis is to show this isolation is complete and that interfaces between safety-critical code and non-safety-critical code do not create hazards.

nonincremental integration. A reformation of a program by immediately relinking the entire program following the testing of each independent module. Integration testing is then conducted on the program as a whole. Syn: "big bang" integration. Contrast with incremental integration.

non-maskable interrupt. A high priority interrupt that cannot be disabled by another interrupt. It can be used to report malfunctions such as parity, bus, and math co-processor errors.

null. (IEEE) A value whose definition is to be supplied within the context of a specific operating system. This value is a representation of the set of no numbers or no value for the operating system in use.

null data. (IEEE) Data for which space is allocated but for which no value currently exists.

null string. (IEEE) A string containing no entries. Note: It is said that a null string has length zero.

Source Documents

1. The New IEEE Standard Dictionary of Electrical and Electronics Terms, IEEE Std. 100-1992.
2. IEEE Standards Collection, Software Engineering, 1994 Edition, published by the Institute of Electrical and Electronic Engineers Inc.
3. National Bureau of Standards [NBS] Special Publication 500-75 Validation, Verification, and Testing of Computer Software, 1981.
4. Federal Information Processing Standards [FIPS] Publication 101, Guideline For Lifecycle Validation, Verification, and Testing of Computer Software, 1983.
5. Federal Information Processing Standards [FIPS] Publication 105, Guideline for Software Documentation Management, 1984.
6. American National Standard for Information Systems, Dictionary for Information Systems, American National Standards Institute, 1991.
7. FDA Technical Report, Software Development Activities, July 1987.
8. FDA Guide to Inspection of Computerized Systems in Drug Processing, 1983.
9. FDA Guideline on General Principles of Process Validation, May 1987.
10. Reviewer Guidance for Computer Controlled Medical Devices Undergoing 510(k) Review, Office of Device Evaluation, CDRH, FDA, August 1991.
11. HHS Publication FDA 90-4236, Preproduction Quality Assurance Planning.
12. MIL-STD-882C, Military Standard System Safety Program Requirements, 19JAN1993.
13. International Electrotechnical Commission, International Standard 1025, Fault Tree Analysis.
14. International Electrotechnical Commission, International Standard 812, Analysis Techniques for System Reliability - Procedure for Failure Mode and Effects Analysis [FMEA].
15. FDA recommendations, Application of the Medical Device GMP to Computerized Devices and Manufacturing Processes, May 1992.
16. Pressman, R., Software Engineering, A Practitioner's Approach, Third Edition, McGraw-Hill, Inc., 1992.
17. Myers, G., The Art of Software Testing, Wiley Interscience, 1979.
18. Beizer, B., Software Testing Techniques, Second Edition, Van Nostrand Reinhold, 1990.
19. Additional general references used in developing some definitions are:
20. Bohl, M., Information Processing, Fourth Edition, Science Research Associates, Inc., 1984.
21. Freedman, A., The Computer Glossary, Sixth Edition, American Management Association, 1993.
22. McGraw-Hill Electronics Dictionary, Fifth Edition, 1994, McGraw-Hill Inc.
23. McGraw-Hill Dictionary of Scientific & Technical Terms, Fifth Edition, 1994, McGraw-Hill Inc..
24. Webster's New Universal Unabridged Dictionary, Deluxe Second Edition, 1979.

The bulk of this information was obtained from FDA.gov.