The author describes the two major supporting elements of X.400, abstract syntax notation one (ASN.1) and remote operations (ROS). Their history, their impact upon open systems interconnection (OSI) to date, and speculation on their future importance are discussed. Built-in types, type constructors, subtype constructors, and tags for ASN.1 are presented. Error types, notation, bind and unbind operations, and realization of operations are discussed for ROS.>

A computer-based message system (CBMS) consists of computer facilities that expedite the creation, management, and nonreal time distribution of messages. These systems are increasingly being used for formal and informal communication, supporting the distribution of textual messages. However, nontext media such as voice and graphics are very important for human interaction, and are becoming more and more important in computer system applications. As a result, there is a growing need for the support of media other than text in CBMS.Before standards for multimedia CBMS can be implemented, there are many technical issues that must be addressed. These range from the design of new mechanisms for the distribution of multimedia mail, to the design of tools needed for editing nontext media. This panel will be discussing issues encountered in the development of multimedia CBMS and an outlook for standards for multimedia computer mail.

Signals processed im 33.3 rev/min disc recording systems suffer some nonlinear distortion at several stages of the recording and manufacturing chain. These distortions are normally considered insignificant compared to those caused by the nonlinearities of the stylus-groove interaction during playback. The nature and measurement of these playback distortions will be discussed. Measured values of distortion produced by RIAA-equalized playback systems will be presented (2nd harmonic distortion of a single-sinewave input signal, amplitude and frequency intermodulation distortion of an SMPTE two-tone input signal, and difference-tone intermodulation distortion of a CCIF two-tone input signal). The audible (and inaudible) effects of specific nonlinearities in the playback process will be demonstrated by playing music and test signals through an electronic simulator of the stylus-groove interaction.

The ARPA computer network (ARPANET) is a nationwide network of diverse autonomous computers connected via a message-switching store-and-forward communications subnet using leased wide-band (50-kbit/s) telephone lines. A primary objective of the ARPANET is to share preexisting programs and data. Many of the difficulties of using remotely generated programs and data are found to be simple format incompatibilities requiring data manipulations like character set conversion, header prefacing and stripping, packing and unpacking of repeated data, generating counters and flags, and field transposition. The data reconfiguration service (DRS) is an attempt to provide a convenient way of performing these data manipulations in order to mediate between superficially incompatible data streams connecting existing programs in the ARPANET. Desiring to match two incompatible input-output streams, an applications programmer specifies a data stream transformation (called a form) written in the data reconfiguration language (DRL). Associating the appropriate form name with the connection between his two programs, the programmer causes the DRS to follow his instructions on how the specified data streams are to be manipulated in the communication required to make the two programs cooperate over the ARPANET. Components of the DRS include the specification of its special-purpose data reconfiguration language, a form compiler to translate forms into fast-running transformation programs, an interpreter to perform high-speed data transformations at application program run time, and a standard set of ARPANET protocols for the routine handling of connections and form specifications between operating systems.