DESIGNER'S NOTEBOOK EK-VBIDS-RM-001 DIGITAL EQUIPMENT CORPORATION CONFIDENTIAL AND PROPRIETARY DIGITAL CONFIDENTIAL & PROPRIETARY ( .... ~•. ... ,,)' VAXBI DESIGNER'S NOTEBOOK EK-VBIDS-RM-001 o Digital Equipment Corporation. Maynard, Massachusetts DIGITAL CONFIDENTIAL & PROPRIETARY First Printing, January 1986 Digital Equipment Corporation makes no representation that the interconnection of its products in the manner described herein will not infringe on existing or future patent rights, nor do the descrip­ tions contained herein imply the granting of license to make, use, or sell equipment constructed in accordance with this description. The information in this document is subject to change without notice and should not be construed as a commitment by Digital Equipment Corporation. Digital Equipment Corporation assumes no responsibility for any errors that may appear in this document. The manuscript for this book was created using generic coding and, via a translation program, was automatically typeset. Book production was done by Educational Services Development and Pub­ lishing in Bedford, MA. Copyright © Digital Equipment Corporation 1985, 1986 All Rights Reserved Printed in U.S.A. The following are trademarks of Digital Equipment Corporation: DEC MASSBUS UNIBUS DECmate PDP ULTRIX DECnet P/OS VAX "----- / DECUS Professional VAXBI DECwriter Rainbow VAXELN DIBOL RSTS VMS ~DmDDmD'" RSX VT RT Work Processor DIGITAL CONFIDENTIAL & PROPRIETARY Contents Preface Chapter 1 Introduction to VAXBI Option Design 1-1 by VAXBI Development Group Overview of VAXBI Option Design 1-3 Design Analysis 1-13 Design Tips and Topics 1-14 Chapter 2 The Instrument Control Adapter 2-1 by Design Analysis Associates Design Requirements and Design Decisions 2-3 Functional and Operational Description 2-6 Chapter 3 VAXBI Module Layout Guide 3-1 by VAXBI Development Group (~\ Overview of VAXBI Modules 3-3 Standard VAXBI Module and the VAXBI Corner 3-15 VAXBI Expansion Module 3-35 Experiences in Building VAXBI Modules 3-38 Appendix A VAXBI BIIC Simulation: Physical Chip Modeling A-1 Appendix B VAXBI Base Layout Package B-1 Index 0···.. ··········'·· ,:, VAXBI Designer's Notebook iii DIGITAL CONFIDENTIAL & PROPRIETARY Preface The purpose of this notebook is to provide a Chapter 2, The Instrument Control Adapter, focus for those who are involved with design­ is an example of a VAXBI option design. The ing options for the VAXBI bus. This book design requirements and the resulting design attempts to put the VAXBI System Reference decisions are described. The option is a Manual into perspective, explaining which por­ master-port-only design. tions of the VAXBI specification option design­ Chapter 3, VAXBI Module Layout Guide, ers need to be most concerned about. Some serves as a guide for engineers and module portions deal with requirements that are imple­ layout designers as they design options and mented by DIGITAL-supplied hardware. The build VAXBI modules. It points out problem option designer need only use the specified areas and reports some of DIGITAL's exper­ hardware to comply with many of the require­ iences. References are made to the appropri­ ments that are detailed in the comprehensive ate module control drawings. specification. Appendix A, VAXBI BIIC Simulation: PhYSical With the proper perspective, designers can Chip Modeling, gives requirements to permit understand more quickly what they need to do. physical chip modeling of the BIIC for simula­ To help them understand how to go about their tion of a VAXBI option. task, we will provide design examples. In addi­ Appendix B, VAXBI Base Layout Package, tion, as design tools become available we will gives information on the documentation and include commentary on their use. databases in the VAXBI Base Layout Package. Intended Audience Related Documentation This notebook is primarily for engineers who • VAXBI System Reference Manual - The design options for VAXBI systems. System specification for the VAXBI bus and the architects and others who want to understand VAXBI primary interface (the BIIC) DIGITAL's design philosophy for the bus will • T1999 - Module Control Drawings for the also find this information useful. Chapter 3, standard VAXBI module which is a guide to module layout, should be read and studied by module layout designers; • T1996 - Module Control Drawings for the this chapter also includes information pertinent VAXBI expansion module to manufacturing. • ELEN 626 - Mechanical outline drawing for Structure of This Manual the standard VAXBI module Chapter 1, Introduction to VAXBI Option • ELEN 633 - VAXBI module layup Design, provides an overview of the VAXBI bus specification and of the documentation from an option The following document provides information designer's point of view. The chapter also about VAX architecture. poses design issues and gives hints for design­ ing options. • VAX-11 Architecture Reference Manual VAXSI Designer's Notebook v DIGITAL CONFIDENTIAL & PROPRIETARY Chapter 1 Introduction to V AXBI Option Design by VAXBI Development Group This chapter provides an overview of the VAXBI bus and of the documen­ tation from an option designer's point of view. The chapter also poses design issues and lists "tips and topics" useful to designers. Contents 0 ;,1 • Overview of VAXBI Option Design DIGITAL's Bus Design Philosophy What DIGITAL Has Defined for You What DIGITAL Has Done for You What Remains for You to Do • Design Analysis • Design Tips and Topics For Your Consideration BIIC Benefits Hardware Cautions o Copyright © 1985 by Digital Equipment Corporation 1-1 DIGITAL CONFIDENTIAL & PROPRIETARY C: Overview of VAXBI Option Design Now that you are the holder of a VAXBITM • The board area required for the license, you have before you a number of docu­ standard bus interface should be minimized. ments, a database, and a job to do. It's your job to design and build a VAXBI option. Where do • The bus should be reliable and easy to you start? You've read the technical summary maintain. of the VAXBI bus, and you've paged through that hefty document, the VAXBI System Refer­ By definition, a bus provides a standard ence Manual. Perhaps you are suffering from method of interconnecting devices within a "spec shock," an affliction that tends to computer system. A device that functions prop­ paralyze. erly in a system and does not disrupt the oper­ In this chapter we want to explain why the ation of other devices within the system is said V AXBI specification is such a lengthy docu­ to be compatible. Furthermore, devices should ment. We also want to make clear what you, as not depend upon a particular system configura­ an option designer, need to be concerned tion for compatibility. Any device for a particu­ about. Because DIGITAL provides the VAXBI lar type of system should function properly with primary interface, your job becomes simpler. any combination of devices for that system. Your primary task is to implement the user DIGITAL has been successful in maintaining interface portion of the option-the logic for software compatibility among the various mem­ the functions required of your particular option. bers of the VAX computer family. The goal of The secondary task is to interface to DIGITAL's the VAXBI Development Group was to attain "VAXBI Corner." Depending on design this same standard of compatibility at the bus choices, this is usually easier than interfacing level. Just as the compatibility of VAX systems to many of today's industry buses. is supported by a very extensive and detailed VAX-11 Architecture Reference Manual, the "" .. We begin by describing DIGITAL's design ( / .... philosophy for the new bus. If you know the compatibility of VAXBI options is supported by goals set for the bus, you can see more clearly the VAXBI System Reference Manual. the reasons for the requirements. "Compatibility," when used in the context of bus operation or of devices, requires a discus­ DIGITAL's Bus Design Philosophy sion of the various levels of compatibility. The After defining its interconnect strategy, VAXBI SRM includes information on all these DIGITAL set up the VAXBI Development Group levels: to carry out one part of the strategy. Decisions • Mechanical, power, environmental made about the new bus to be designed and built by this group were guided by the • Electrical following: • Logical • The bus should offer high bandwidth. • Software/architectural • The bus should support multiprocessing and caching. We have provided rules to help ensure com­ patibility among all VAXBI options. In practical • The bus should be fully specified. terms, it is not possible to achieve 100 percent • The hardware should be built and tested to compatibility, for specifications would have to the full extent of the specified requirements. define every aspect of the bus from the electri­ cal signals to software behavior. However, we • As far as possible, the bus protocol should believe that we have moved far beyond previ­ preserve data integrity in single-bit failure ous efforts at providing a bus that offers conditions, and when bus errors occur, they compatibility. should be easy to diagnose. The following pages explain what efforts we • It should be a general purpose bus took to ensure that compatibility characterizes designed from a system perspective. VAXBI systems. * VAXBI is a trademark of Digital Equipment Corporation. Introduction to VAXBI Option Design 1-3 DIGITAL CONFIDENTIAL & PROPRIETARY • We first discuss What DIGITAL has defined blesome to bus users in the past because of for you. The specification for the VAXBI bus lack of definition have been specified for the addresses various levels of compatibility. VAXBI. For example, on some buses device We explain the intent of the specification and types are associated with specific address give some examples of what has been locations. However, on the VAXBI bus, control defined. and status registers for a particular device are located in a predefined section of I/O space . • We then explain What DIGITAL has done for Sixteen sections are defined; one section is you.