ISO/IEC 15205:2000

INTERNATIONAL ISO/IEC
STANDARD
IEEE
Std 1496
First edition
2000-06
SBus – Chip and module interconnect bus
Reference number
IEEE
Std 1496, 1993 Edition
Abstract: An input/output expansion bus with a 32- or 64-bit width is described in this standard.
The SBus is designed for systems requiring a small number expansion ports. SBus Cards
may be connected to a standard Sbus Connector mounted on the motherboard. SBus Devices
may also be attached to the SBus directly on the system's motherboard. The dimensions of
the SBus Card are 83,8 mm by 146,7 mm, making the cards appropriate for small computer
systems that make extensive use of highly integrated circuits. The SBus Cards are designed
to be installed in a plane parallel to the system's motherboard as mezzanine cards. They are
designed to provide connections for devices external to the computer system through an
exposed back panel. The form factor is useful in Futurebus+, VMEbus, desktop computers,
and similar applications. The SBus has the capability of transferring data at rates up to
168 Mbytes/s, depending on the implementation options selected.
SBus Cards may either serve as Masters on the bus, providing all virtual address information
as well as the data to be transferred, or they may serve as Slaves on the bus, providing data
transfer according to the requirements of some other SBus Master. The SBus Master for a
data transfer is selected by an arbitration process managed by the single SBus Controller on
the SBus. The SBus Controller provides a virtual to physical address translation service.
Keywords: I/O bus, SBus, SBus Card, Standard for Boot Firmware.

––––––––––
The Institute of Electrical and Electronics Engineers, Inc.
345 East 47th Street, New York, NY 10017-2394, USA
Copyright © 1993 by the Institute of Electrical and Electronics Engineers, Inc.
All rights reserved. First published in 1993.
ISBN 2-8318-5165-3
No part of this publication may be reproduced in any form, in an electronic retrieval system or otherwise, without
the prior written permission of the publisher.

INTERNATIONAL ISO/IEC
STANDARD
IEEE
Std 1496
First edition
2000-06
SBus – Chip and module interconnect bus
Sponsor
Bus Architecture Standards Committee
of the IEEE Computer Society
PRICE CODE
X
For price, see current catalogue

– 2 – ISO/IEC 15205:2000(E)
IEEE Std 1496, 1993 Edition
CONTENTS
Page
FOREWORD . 4
INTRODUCTION .5
Clause
1 General. 8
1.1 Scope and object . 8
1.2 Normative references. 8
2 Definitions, usage of special terms, acronyms, and editorial conventions . 9
2.1 Definitions . 9
2.2 Usage of special terms . 13
2.3 Acronyms. 13
2.4 Editorial conventions. 13
3 Overview. 14
3.1 System overview. 14
3.2 Overview of configurations. 16
3.3 General design information . 19
3.4 Performance . 21
4 Signal definitions . 23
4.1 CLK signal . 23
4.2 RST* signal . 24
4.3 PA[27:0] signals. 25
4.4 SEL* signal. 25
4.5 AS* signal. 26
4.6 BR* signal. 26
4.7 BG* signal . 26
4.8 D[31:0], D[63:0], and DP signals . 27
4.9 SIZ[2:0] signals. 28
4.10 RD signal. 28
4.11 ACK[2:0]* signals. 29
4.12 LERR* signal . 31
4.13 INT[7:1]* signals . 32
5 SBus cycle definitions . 33
5.1 Arbitration Phase . 33
5.2 Translation Phase. 34
5.3 Extended Transfer Information Phase . 36
5.4 Transfer Phase . 40
5.5 Dual function SBus Devices . 58
5.6 Exception conditions. 59
5.7 Extended Transfer locking protocol . 60
Copyright © 1993 IEEE. All rights reserved.

IEEE Std 1496, 1993 Edition
Clause Page
6 SBus electrical requirements. 62
6.1 Power . 62
6.2 Electronic characteristics . 63
6.3 Electronic timing requirements . 66
6.4 Compliance requirements . 69
7 Environmental requirements. 69
7.1 Operating range. 69
8 Mechanical requirements . 70
8.1 SBus Slot Connector. 70
8.2 SBus Card . 74
8.3 Panel installation . 88
9 SBus program interface . 89
9.1 Introduction. 89
9.2 Program format and interpretation . 89
9.3 Required FCode attributes . 90
9.4 FCode language . 90
9.5 Special functions of Word 0 . 90
Annex A (informative) Compliance checklist . 92
Annex B (informative) Known implementation variations. 97
Bibliography . 101
Index . 102
Copyright © 1993 IEEE. All rights reserved.

– 4 – ISO/IEC 15205:2000(E)
IEEE Std 1496, 1993 Edition
SBus – CHIP AND MODULE INTERCONNECT BUS
FOREWORD
1) ISO (the International Organization for Standardization) and IEC (the International Electrotechnical
Commission) form the specialized system for worldwide standardization. National bodies that are members of
ISO or IEC participate in the development of International Standards through technical committees established
by the respective organization to deal with particular fields of technical activity. ISO and IEC technical
committees collaborate in fields of mutual interest.Other international organizations, governmental and non-
governmental, in liaison with ISO and IEC, also take part in the work.
2) In the field of information technology, ISO and IEC have established a joint technical committee, ISO/IEC
JTC 1. Draft International Standards adopted by the joint technical committee are circulated to national bodies
for voting. Publication as an International Standard requires approval by at least 75 % of the national bodies
casting a vote.
3) Attention is drawn to the possibility that some of the elements of this International Standard may be the
subject of patent rights. ISO and IEC shall not be held responsible for identifying any or all such patent rights.
International Standard ISO/IEC 15205 was prepared by subcommittee 26: Microprocessor
systems, of ISO/IEC joint technical committee 1: Information technology.
International Standards are drafted in accordance with ISO/IEC Directives, Part 3.
Annexes A and B are for information only.
This standard must be used in conjunction with the latest edition of the following standard:
IEEE Std 1275.
International Electrotechnical Commission • 3, rue de Varembé, PO Box 131,
CH-1211-Geneva 20, Switzerland • Telephone: +41 22 919 0211 •
Telefax: +41 22 919 0300 • e-mail: inmail@iec.ch •
URL: http://www.iec.ch
Copyright © 1993 IEEE. All rights reserved.

IEEE Std 1496, 1993 Edition
INTRODUCTION
(This introduction is not a normative part of ISO/IEC 15205:2000, but is included for
information only.)
This IEEE standard documents the implementation of the popular SBus interface. The SBus,
originally developed and documented by Sun Microsystems as an I/O expansion bus, uses a
standard form factor SBus Card that is a suitable size for the use of VLSI circuits in small
computers. It has a high bandwidth and is capable of data transfer 8, 16, 32, or 64 bits in
width. This standard includes the set of functionality originally documented by the SBus
Specification B.0 (Sun Microsystems Part #800.5922-10, Revision A, December 1990) and
clarifies, corrects, and extends that functionality as required. The IEEE P1275 Working Group
is developing a standard for boot firmware, which will define and document the initialization
and boot interface for SBus Cards.
Special thanks are due to Bob Snively (P1496 Working Group draft technical editor) for the
many hours spent in converting this document from the original SBus Specification B.0 and
editing it into its final form. Also deserving of thanks are Jim Lyle (P1496 Working Group vice
Chair), Barbara Vance (P1496 Working Group former Secretary), Bob Gianni (P1496 Working
Group Secretary), and Steve Hix (P1496 draft document editor) for their support in the
Committee work and the generation of this document.
The following people were members of the P1496 Working Group that approved the draft for
submission to IEEE for sponsor ballot:
Wayne Fischer, Chair
James Lyle, Co-Chair
Robert Gianni, Secretary
Robert Snively, Draft Technical Editor
Sanjay Adkar Steve Golson Elwood Parsons
Steven W. Aiken Anthony A. Goodloe Heinz Piorunneck
Ray S. Alderman James N. Hardage, Jr. Jack Regula
Ravi Anantharaman Hans Heilborn Eayne Rickard
James Antonellis Kai Holz Michael Saari
Tom Armbruster Timothy Hu Siamak Salimpour
Jon K. Bennett Mohammad Issa Gary Sloane
C.J. Beynon Shinkyo Kaku Martin Sodos
Paul Borrill Kuljeet Kalkat Richard Spratt
Mike Chastain Thomas Kappler Mike Strang
Gary Croak Bill Keshlear Lars Themsjö
Scott Eichmann Gary Kidwell David Therrien
Robert Elliott Erik Kristenson Istvan Vadasz
Jurgen Fey Ernst H. Kristiansen Barbara Vance*
Larry Fiedler Joel Libove Naor Wallach
William A. Fox James Ludemann Eike Waltz
Paul Fulton Susan Mason Leo Yuan
Brad Giffel Shrenik Mehta Janusz Zalewski
Donald J. Murphy
* Former Secretary
Copyright © 1993 IEEE. All rights reserved.

– 6 – ISO/IEC 15205:2000(E)
IEEE Std 1496, 1993 Edition
The following persons were on the balloting committee:
Amir Abouelnaga Larry E. Gerald Richard Mueller
Edward W. Aichinger Robert R. Gianni Michael Orlovsky
Ray S. Alderman Steve Golson Mira Pauker
Richard P. Ames Julio Gonzalez-Sanz Philip K. Piele
Keith D. Anthony John Griffith Rochit Rajsuman
Behrooz Bandall Hans H. Heilborn Brian Ramelson
Chris Bezir
...