IEEE 1394a-2000

This is a full-use standard whose scope is to provide a supplement to IEEE Std 1394-1995 that defines or clarifies features and mechanisms that facilitate management of Serial Bus resources, at reconfiguration or during normal operation, and that defines alternate cables and connectors that may be needed for specialized applications. The following are included in this supplement: a) Cables and connectors for a 4-pin variant (from the 6-pin already standardized); b) Standardization of the PHY/link interface, previously published as informative annex to IEEE Std 1394-1995; c) Performance enhancements to the PHY layer that are interoperable with the existing standard, e.g., a method to shorten the arbitration delay when the last observed Serial Bus activity is an acknowledge packet; d) A redefintion of the isochronous data pakcet, transaction code A16, to permit its use in either the asynchronous or isochronous periods; e) More stringent requirements on the power to be supplied by a cable power source and a clarification of electrical isolation requirements; and f) Significant corrigenda and clarifications to the existing standard that do not clearly fall within any of the topics described above. The preceding are arranged in no particular order. Experience with Serial Bus has revealed some areas in which additional features or improvements may result in better performance or usability. This supplement to IEEE Std 1394-1995 reflects their consideration by a variety of users and their refinement into generally useful facilities or features. Amendment Standard - Superseded. Amended information for a high-speed Serial Bus that integrates well with most IEEE standard 32-bit and 64-bit parallel buses is specified. This amendment is intended to extend the usefulness of a low-cost interconnect between external peripherals, as described in IEEE Std 1394-1995. This amendment to IEEE Std 1394-1995 follows the ISO/IEC 13213:1994 Command and Status Register (CSR) Architecture.