Content Description

The overall level of performance that may be achieved by any computer system is determined, in large part, by the system bus that is used to effect communication between the various system elements. System performance characteristics, measured in terms of speed, reliability, suitability to a variety of purposes, and adaptability to changing technology are ultimately dependent on the particular bus structure that is used and its associated protocols.

This standard defines the IEEE Std 1000 Bus, which may be used to implement general purpose, high-performance 8-bit microcomputer systems. Such a system may be used in a stand-alone configuration, or in larger multiple-bus architectures, as a private (or secondary) bus or a high-speed I/O channel. This standard is applicable to those systems and system elements with the common commercial designation STEbus. It is intended for those users who plan to evaluate, implement, or design various system elements that are compatible with the IEEE 1000 Std Bus system structure.

The physical attributes and method of interconnect utilized by boards and modules conforming to this standard are derived from several International Electrotechnical Commission (IEC) standards. These standards, when implemented jointly in a systems environment, result in a mechanical configuration commonly referred to as Eurocard. Appendix B lists such applicable standards which, where referenced, are considered as if incorporated with this standard. In particular, the connector used by IEEE Std 1000 Bus boards is a 64-pin male connector utilizing the outside two rows (designated a and c rows), specified in IEC 60603-2, and the mating female connector is used on IEEE Std 1000 Bus backplanes. The recommended size for IEEE Std 1000 Bus boards is 100 mm × 160 mm (3,937 in × 6,299 in), commonly referred to as a single height standard depth Eurocard.

The IEEE Std 1000 Bus structure is based on the master-slave concept in which a master, having gained control of the bus, may address and command slaves. Masters and slaves communicate with each other by use of an asynchronous interlocked handshake protocol. This technique allows for the construction of computer systems that incorporate devices of widely varying speeds. Multiple masters may be implemented within a single system.

Two independent address spaces are supported: memory and I/O. Memory transactions reference a 1 megabyte physical address space, while I/O transactions reference a 4 kilobyte physical address space. System integrity during all such transactions is enhanced by provision of a transfer error signal. Provision is made for interboard condition alerts such as interrupt requests, DMA requests, system-specific error conditions, or other specialized status conditions. Within this scheme eight prioritized attention request levels, each with vectored response capability, are available for user assignation.

This standard deals only with those characteristics that must be specified so as to ensure the successful design and implementation of compatible boards and systems. Issues relating to individual design specifications, and performance or safety requirements are not addressed.

About ISO

ISO, the International Organization for Standardization, brings global experts together to agree on the best way of doing things – for anything from making a product to managing a process. As one of the oldest non-governmental international organizations, ISO has enabled trade and cooperation between people and companies all over the world since 1946. The International Standards published by ISO serve to make lives easier, safer and better.