Digital Equipment AXPpci 33 Guide

DigitalAXPpci33
Alpha PC Motherboard
OEMDesignGuide
Order Number: EK–AXPCI–DG. C01
This guide supplies reference, configuration, and installation information for
the Digital AXPpci 33 Alpha PC motherboard.
Revision/Update Information: This manual supersedes the Digital AXPpci
33 Alpha PC Motherboard OEM Design
Guide , EK–AXPCI–DG. B01.
Digital Equipment Corporation
Maynard, Massachusetts

First Printing, October 1994
Revised, August 1995
While Digital believes the information in this publication is correct as of the date of
publication, it is subject to change without notice.
Digital Equipment Corporation makes no representations that the use of its products
in the manner described in this publication will not infringe on existing or future
patent rights, nor do the descriptions contained in this publication imply the granting
of licenses to make, use, or sell equipment or software in accordance with the
description.
© Digital Equipment Corporation 1994, 1995. All Rights Reserved.
Printed in U.S.A.
The postpaid Reader’s Comments form at the end of this document requests your
critical evaluation to assist in preparing future documentation.
The following are trademarks of Digital Equipment Corporation: Alpha AXP, AXP,
DEC, DECchip, and the DIGITAL logo.
The following are third-party trademarks:
AT and PS/2 are registered trademarks of International Business Machines, Inc.
IEEE is a registered trademark of the Institute of Electrical and Electronic Engineers,
Inc.
Intel is a registered trademark of Intel Corporation.
Grafoil is a trademark of Aavid Engineering, Inc.
Microsoft and MS–DOS are registered trademarks and Windows NT is a trademark of
Microsoft Corporation.
NCR is a registered trademark of NCR Corporation.
UNIX is a registered trademark in the United States and other countries licensed
exclusively through X/Open Company Ltd.
VxWorks is a registered trademark of Wind River Systems, Inc.
All other trademarks and registered trademarks are the property of their respective
holders.
S2843

Contents
PREFACE xi
CHAPTER 1 SYSTEM SUMMARY 1–1
CHAPTER 2 PHYSICAL DESCRIPTION 2–1
2.1 CORE MODULE ASSEMBLY 2–1
2.2 MAIN LOGIC BOARD 2–1
2.2.1 Physical Mounting 2–2
2.2.2 Connectors 2–3
2.2.2.1 DC Power Input Connectors (J33 and J34) • 2–3
2.2.2.2 Engineering and Manufacturing Test Connector (J32) • 2–6
2.2.2.3 Fan Connector (J1) • 2–7
2.2.2.4 Floppy Disk Connector (J12) • 2–7
2.2.2.5 Halt/Reset Switch Connector (J11) • 2–8
2.2.2.6 IDE Disk Connector (J18) • 2–8
2.2.2.7 ISA Slot Connectors (J20–J24) • 2–9
2.2.2.8 Keyboard Connectors (J39 and J38) • 2–9
2.2.2.9 Keylock and Power LED Connector (J9) • 2–10
2.2.2.10 LED Display Connector (J6) • 2–11
2.2.2.11 Mouse Connector — PS/2 Compatible (J40) • 2–13
2.2.2.12 Parallel Port Connector (J36) • 2–14
2.2.2.13 PCI Slot Connectors (J25–J27) • 2–14
2.2.2.14 SCSI/IDE Busy LED Connector (J14) • 2–14
2.2.2.15 SCSI–2 Cable Connector (J19) • 2–15
2.2.2.16 Serial Ports COM1 (J35) and COM2 (J37) • 2–16
2.2.2.17 SIMM Interconnect (J2–J5) • 2–17
2.2.2.18 Speaker Connector (J10) • 2–18
2.2.3 Device Sockets 2–19
2.2.3.1 AXPpci 33 Processor Socket (XE15) • 2–19
2.2.3.2 Cache Sockets (XE100–XE110) • 2–19
2.2.4 MLB Jumpers 2–20
2.2.4.1 Cache Speed Select (J17) • 2–20
2.2.4.2 CPU Clock Frequency Select Jumper (J7) • 2–20
2.2.4.3 Halt/Reset Select Jumper (J8) • 2–21
2.2.4.4 IDE DMA Request and Grant Jumpers (J15 and J16) • 2–22
2.2.4.5 SROM Select Jumpers (J28 and J29) • 2–22
2.2.4.6 SCSI Terminator Jumper (J13) • 2–23
iii

Contents
2.3 SINGLE INLINE MEMORY MODULES 2–24
2.3.1 Connector 2–24
2.3.2 Physical Mounting 2–25
2.4 ISA OPTION MODULES 2–25
2.5 PCI OPTION MODULES 2–26
CHAPTER 3 ENVIRONMENTAL DATA 3–1
3.1 COOLING REQUIREMENTS 3–1
3.1.1 Air Flow 3–1
3.1.2 DECchip 21066 Heatsink Selection 3–1
3.1.2.1 DECchip 21066 (166 MHz) Cooling Requirements • 3–2
3.1.2.2 DECchip 21066A (233 MHz) Cooling Requirements • 3–4
3.1.2.3 DECchip 21068 (66 MHz) Cooling Requirements • 3–5
3.1.2.4 DECchip 21068A (100 MHz) Cooling Requirements • 3–6
3.1.2.5 Custom Heatsink Design • 3–8
3.2 DC POWER INPUTS 3–9
3.2.1 System Power Requirements 3–9
3.2.2 Power Sequencing 3–10
3.2.3 POWER GOOD Signal 3–10
3.3 ELECTROSTATIC DISCHARGE CONSIDERATIONS 3–11
3.4 TELECOMMUNICATION REGULATORY STANDARDS 3–11
3.5 ELECTROMAGNETIC COMPATIBILITY CONSIDERATIONS 3–11
3.6 RELIABILITY DATA 3–12
APPENDIX A SUPPLIERS AND PART NUMBERS A–1
A.1 MAIN LOGIC BOARD CONFIGURATIONS A–1
iv

Contents
A.2 ACCESSORIES AND SUPPLIERS A–4
APPENDIX B CONNECTOR SUMMARY B–1
APPENDIX C TESTED OPTIONS C–1
APPENDIX D INSTALLATION AND HANDLING INSTRUCTIONS D–1
D.1 ANTISTATIC PRECAUTIONS D–1
D.2 INSTALLATION INSTRUCTIONS D–1
D.2.1 Heatsink Labeling D–1
D.2.2 Grafoil Thermal Pad — Pick and Place D–1
D.2.3 Heatsink Attachment D–1
D.2.4 Heatsink Removal/Replacement D–2
D.2.5 Heatsink Assembly Instructions D–2
D.2.6 Heatsink/Fan Assembly Instructions D–3
D.2.7 Installation into ZIF Socket D–3
D.3 SIMM INSTALLATION AND REMOVAL INSTRUCTIONS D–4
D.4 CACHE INSTALLATION INSTRUCTIONS D–5
APPENDIX E CONSOLE COMMANDS E–1
E.1 OVERVIEW E–1
E.2 ARC CONSOLE E–1
E.2.1 Menu Option: Boot Windows NT E–1
E.2.2 Menu Option: Boot an Alternate Operating System E–1
E.2.3 Menu Option: Supplementary Menu E–2
E.2.3.1 Menu Option: Install New Firmware • E–2
E.2.3.2 Menu Option: Install Windows NT from CD–ROM • E–2
E.2.3.3 Menu Option: Set Up the System • E–2
E.2.3.3.1 Menu Option: Display Hardware Configuration • E–3
v

Contents
E.3 SRM CONSOLE E–3
E.3.1 Conventions E–4
E.3.2 Special Characters E–4
E.3.3 boot Command E–5
E.3.3.1 Syntax • E–5
E.3.3.2 Options • E–5
E.3.3.3 Examples • E–6
E.3.4 set Command E–6
E.3.4.1 Syntax • E–6
E.3.4.2 Options • E–6
E.3.4.3 Examples • E–6
E.3.5 show Command E–7
E.3.5.1 Syntax • E–7
E.3.5.2 Options • E–7
E.3.5.3 Examples • E–8
E.3.6 Environment Variables E–8
E.3.7 examine Command E–8
E.3.7.1 Syntax • E–8
E.3.7.2 Options • E–9
E.3.7.3 Examples • E–9
E.3.8 deposit Command E–10
E.3.8.1 Syntax • E–10
E.3.8.2 Options • E–10
E.3.8.3 Examples • E–11
E.3.9 ISA Configuration Utility, isacfg E–11
E.3.9.1 Syntax • E–12
E.3.9.2 Options • E–12
E.3.9.3 Examples • E–13
E.3.9.4 add_de205 Command • E–14
APPENDIX F OPERATING SYSTEM INSTALLATION NOTES F–1
F.1 GETTING STARTED F–1
F.2 HOW TO OBTAIN THE LATEST FIRMWARE F–1
F.3 WINDOWS NT INSTALLATION NOTES F–1
F.3.1 How to Plan and Create Your Disk Partitions F–2
F.3.2 Installing ISA and PCI Option Cards F–2
F.4 DIGITAL UNIX INSTALLATION NOTES F–2
vi

Contents
APPENDIX G FREQUENTLY ASKED QUESTIONS G–1
G.1 WINDOWS NT SYSTEM CONFIGURATION G–1
G.2 DIGITAL UNIX SYSTEM CONFIGURATION G–3
EXAMPLES
E–1 Typical Windows NT Console Menu E–1
E–2 Sample Supplementary Menu E–2
E–3 Sample Setup Menu E–2
E–4 Sample Boot Selection Menu E–3
FIGURES
1–1 Main Logic Board 1–4
2–1 Core Module Assembly Outline 2–2
2–2 MLB Mechanical Drawing 2–4
2–3 MLB Component Outline Drawing 2–5
2–4 Halt/Reset Switch Circuit 2–8
2–5 Keylock and Power LED Circuit 2–11
2–6 LED Display Circuit 2–12
2–7 SCSI/IDE Busy LED Circuit 2–15
2–8 Speaker Circuit 2–19
2–9 Cache Socket 2–20
2–10 SROM Select Jumper Positions (J28 and J29) 2–23
2–11 Use of the Terminator on the SCSI Bus 2–23
2–12 Example SIMM Outline 2–24
2–13 Typical ISA Option Module 2–25
2–14 Typical PCI Option Drawing 2–26
3–1 POWER GOOD Timing Diagram 3–10
D–1 Heatsink Assembly D–2
D–2 Fan/Heatsink Assembly D–3
D–3 SIMM Installation D–5
TABLES
1 Conventions xi
1–1 Digital AXPpci 33 System Summary 1–1
1–2 SPECint92, SPECfp92, Dhrystone VI, and Whetstone Performance
Metrics 1–3
1–3 Rhealstone Performance Metrics 1–3
vii

Contents
2–1 DC Power Connector (±5 V/±12 V) Pin-Out (J33) 2–6
2–2 DC Power Connector (+3.3 V) Pin-Out (J34) 2–6
2–3 Fan Connector Pin-Out (J1) 2–7
2–4 Floppy Disk Connector Pin-Out (J12) 2–7
2–5 Halt/Reset Switch Connector Pin-Out (J11) 2–8
2–6 IDE Disk Connector Pin-Out (J18) 2–8
2–7 Keyboard Connector — AT Style Pin-Out (J39) 2–10
2–8 Keyboard Connector — PS/2 Style Pin-Out (J38) 2–10
2–9 Keylock and Power LED Connector Pin-Out (J9) 2–10
2–10 LED Display Connector Pin-Out (J6) 2–12
2–11 LED Display Codes 2–13
2–12 Mouse Connector Pin-Out (J40) 2–13
2–13 Parallel Port Connector Pin-Out (J36) 2–14
2–14 SCSI/IDE Busy LED Connector Pin-Out (J14) 2–15
2–15 SCSI–2 Connector Pin-Out (J19) 2–15
2–16 Serial Ports COM1 (J35) and COM2 (J37) Pin-Outs 2–16
2–17 SIMM Connector Pin-Outs (J2–J5) 2–17
2–18 Speaker Connector Pin-Out (J10) 2–18
2–19 Cache Speed Select Jumper (J17) 2–20
2–20 CPU Clock Frequency Select Jumper (J7) 2–21
2–21 Halt/Reset Select Jumper (J8) 2–21
2–22 Halt/Reset Operational Settings 2–21
2–23 IDE DMA Request Jumper (J15) 2–22
2–24 IDE DMA Grant Jumper (J16) 2–22
2–25 SROM Select Jumpers (J28 and J29) 2–22
2–26 SCSI Terminator Jumper (J13) 2–23
2–27 SIMM Options 2–25
2–28 Variable Lengths of ISA Options 2–26
2–29 Variable Lengths of PCI Options 2–27
3–1 DECchip 21066 Maximum Case Temperature Limits 3–1
3–2 DECchip 21066 (166 MHz) Cooling Using Low-Profile Heatsink 3–2
3–3 DECchip 21066 (166 MHz) Cooling Using High-Profile Heatsink 3–3
3–4 DECchip 21066 (166 MHz) Cooling Using Fan/Heatsink 3–3
3–5 DECchip 21066A (233 MHz) Cooling Using Low-Profile Heatsink 3–4
3–6 DECchip 21066A (233 MHz) Cooling Using High-Profile Heatsink 3–4
3–7 DECchip 21066A (233 MHz) Cooling Using Fan/Heatsink 3–5
3–8 DECchip 21068 (66 MHz) Cooling Using Low-Profile Heatsink 3–5
3–9 DECchip 21068 (66 MHz) Cooling Using High-Profile Heatsink 3–6
3–10 DECchip 21068 (66 MHz) Cooling Using Fan/Heatsink 3–6
3–11 DECchip 21068A (100 MHz) Cooling Using Low-Profile Heatsink 3–7
3–12 DECchip 21068A (100 MHz) Cooling Using High-Profile Heatsink 3–7
3–13 DECchip 21068A (100 MHz) Cooling Using Fan/Heatsink 3–8
3–14 System DC Power Requirements (Using 21066 at 166 MHz) 3–9
3–15 System DC Power Requirements (Using 21066A at 233 MHz) 3–9
3–16 System DC Power Requirements (Using 21068 at 66MHz) 3–9
viii

Contents
3–17 System DC Power Requirements (Using 21068A at 100 MHz) 3–9
3–18 POWER GOOD — Undervoltage Threshold 3–11
3–19 POWER GOOD — Electrical Characteristics 3–11
3–20 MTBF Data for the AXPpci 33 MLB 3–12
A–1 MLB and Bundled Kit Configurations A–1
A–2 MLB Options A–3
A–3 Accessories and Suppliers A–4
B–1 MLB Connectors and Jumpers B–1
C–1 Tested Options C–1
E–1 SRM Console Conventions E–4
E–2 SRM Console Special Characters E–4
E–3 boot Command Options E–5
E–4 boot Command Examples E–6
E–5 set Command Options E–6
E–6 set Command Examples E–7
E–7 show Command Options E–7
E–8 show Command Examples E–8
E–9 Environment Variables E–8
E–10 examine Command Options E–9
E–11 examine Command Examples E–9
E–12 deposit Command Options E–10
E–13 deposit Command Examples E–11
E–14 isacfg Command Options E–12
E–15 isacfg Command Examples E–13
G–1 IRQ Defaults G–2
ix

Preface
This guide supplies reference, configuration, and installation information
for the Digital AXPpci 33 Alpha PC motherboard. Included are details on
physical, electrical, environmental, and operational characteristics.
The guide furnishes system integration customers with design details of
the motherboard so they can integrate this subsystem component into a
standard or custom application. Information about console commands is
also supplied.
Digital tried to provide every detail required for design integration in one
complete and concise document. If you find any errors or omissions, please
inform Digital so that the quality and completeness of this and future
documents can be enhanced.
Document Structure
This guide contains three chapters and seven appendixes:
Chapter 1 Provides overall system characteristics.
Chapter 2 Describes dimensions, connectors, mounting, and configurable
features of the module and connectors.
Chapter 3 Supplies required environmental constraints.
Appendix A Contains part numbers for orderable main logic boards (MLBs),
bundled kit configurations, MLB options, and accessories.
Appendix B Lists and briefly describes all connectors and jumpers used on the
MLB.
Appendix C Lists tested options.
Appendix D Provides installation and handling instructions.
Appendix E Describes the console commands.
Appendix F Presents information for installing Digital UNIX and Windows NT.
Appendix G Lists frequently asked questions about configuring the AXPpci 33
for Digital UNIX and Windows NT systems.
Conventions The following conventions are used in this guide:
Table 1 Conventions
Convention Meaning
Ctrl/ x Press the key labeled Ctrl while you simultaneously
press another key. For example: Ctrl/C.
xi

Preface
Table 1 (Cont.) Conventions
Convention Meaning
italic type The following items appear in italic type:
• Variable information, such as user-supplied
information in commands. For example:
>>> set envar value [-default] [-integer]
[-string]
• Directory and file specifications when these appear
in text. For example:
The files are located in the directory
pub/Digital/axppci .
bold type This typeface indicates the name of a console command
or command option when it appears in text. For example:
Use the set boot_osflags command to set an
environment variable that specifies a default boot
flag value.
[] Square brackets, in command syntax, enclose optional
items. For example:
>>> set envar value [-default] [-integer]
[-string]
. . . Horizontal ellipsis points indicate that the preceding item
can be repeated one or more times. These are used in
syntax descriptions and function definitions.
Horizontal ellipsis points also indicate that a portion of an
example or figure is omitted.
Key In tables, key names are designated by a box. For
example, Return .
DECchip 21066 Except where noted differently, DECchip 21066 refers to
the DECchip 21066/21066A/21068/21068A processor.
MLB Main logic board refers to the system module or
motherboard with the DECchip 21066 processor chip
socket.
PCB Printed circuit board, also known as a printed wire board.
Side 1 The primary component (DECchip 21066) side of a
printed circuit board.
Side 2 The passive component side of a printed circuit board.
Figure dimensions Except where noted differently, all figure dimensions are
in inches.
xii

Preface
Reference Documents
The next sections list associated documents to which you may want to
refer.
Digital Documents
•Digital AXPpci 33 Data Sheet (EC–F2938–56)
•Alpha AXP Architecture Reference Manual (EY–L520E–DP)
•Alpha AXP Architecture Handbook (EC–H1689–10)
•AlphaServer 2000/2100 Firmware Guide (EK–AXPFW–RM)
•DECchip 21066/21066A Microprocessor Chip Data Sheet
(EC–QC4HA–TE)
•DECchip 21068 Microprocessor Chip Data Sheet (EC–N0627–72)
•DECchip 21066 and DECchip 21068 Alpha AXP Microprocessor
Hardware Reference Manual (EC–N2681–72)
Third-Party Documents
Contact these organizations for the latest revisions of the documents:
•PCI Local Bus Specifications
PCI Special Interest Group
M/S HF3–15A
5200 N.E. Elam Young Parkway
Hillsboro, Oregon 97124–6497
Telephone: [phone]
•ISA Bus Specification P996
IEEE Service Center
445 Hoes Lane
P.O. Box 1331
Piscataway, New Jersey 08855
•Intel 180 Watt Baby–AT +3.3/5 V Switching Power Supply
Specification
Intel Corporation
Literature Sales
P.O. Box 7641
Mt. Prospect, IL 60056–7641
Telephone: [phone]
xiii

1SystemSummary
This chapter presents the physical, performance, and operating
characteristics of the Digital AXPpci 33 motherboard.
Table 1–1 includes features of the DECchip 21066 processor used for
the Digital AXPpci 33. Features are common across all versions of the
motherboard unless specifically differentiated.
Table 1–1 Digital AXPpci 33 System Summary
Software
Operating systems Microsoft Windows NT, Digital UNIX
System Characteristics
CPU and clock speed DECchip 21066 RISC microprocessor at 166 MHz (6 ns)
DECchip 21066A RISC microprocessor at 233 MHz (4.3 ns)
DECchip 21068 RISC microprocessor at 66 MHz (15 ns)
DECchip 21068A RISC microprocessor at 100 MHz (10 ns)
Processor upgradeable ZIF socket for DECchip 21066 processor upgrades
Instruction issue Up to two instructions issued per clock cycle
Word size 64 bits
Address size
 Physical address: 34 bits
 Virtual address: 43 bits
Floating-point format VAX (F and G) and IEEE
Memory (RAM)
Minimum
Maximum
Recommended minimums
8 MB ECC protected
256 MB ECC protected
Windows NT: 16 MB
Digital UNIX: 32 MB
Memory (ROM) 512 KB flash ROM
External cache Configurable for 0, 256 KB, or 1 MB
(64 data bits and 8 ECC protection bits; 20 ns or 15 ns access)
Memory bus width 64 data bits and 8 ECC bits
Memory bus speed (peak) 80 MB/s
Graphics
Integral graphics None included.
Graphics options See Appendix C for a list of tested options.
1–1

System Summary
Table 1–1 (Cont.) Digital AXPpci 33 System Summary
Input/Output
Input device interfaces AT or PS/2 style keyboard and mouse.
Serial Two RS–423 (9-position) compatible serial communications ports.
Parallel One parallel (Centronics compatible) communications port.
Bus options Total of seven option slots.
PCI Peripheral component interconnect. Supports three 5 V/32-bit PCI
(33 MHz) option slots with a peak performance of 132 MB/sec: two
long (12.354 inches) and one short (6.946 inches) module. One
long PCI slot shares the same bulkhead slot with one long ISA
(industry-standard architecture) slot. See Appendix C for a list of
tested options.
ISA Supports five ISA option slots: two long (13.415 inches) and three
short (6.945 inches) modules. One long ISA slot shares the same
bulkhead with one long PCI slot. See Appendix C for a list of tested
options.
FAST SCSI–2 One NCR 53C810 SCSI controller supporting a single-ended bus.
One internal SCSI connector; seven devices plus a controller.
Asynchronous operation at 5 MB/s or synchronous operation at
10 MB/s. See Appendix C for a list of tested options.
IDE One IDE interface supporting up to two drives.
Floppy One 82077-compatible diskette controller supporting up to two drives:
 For Windows NT: 1.2 MB, 1.44 MB, and 2.88 MB formats.
 For Digital UNIX: 1.44 MB and 2.88 MB formats.
See Appendix C for a list of tested options.
Physical Characteristics
Form factor Baby–AT system module
Width/depth/height
(with the DECchip 21066, high-profile
heatsink and option modules)
English: 8.65 inches/13.865 inches/5.573 inches
Metric: 220 mm/353 mm/142 mm
Weight
(with the DECchip 21066 and high-profile
heatsink)
1.85 lbs/840 grams
Power supply voltages
(main logic board [MLB] only) +5 V, +12 V, -12 V, -5 V (+3.3 V supply connection is available for PCI options.)
Refer to Chapter 3 for current consumption.
Environmental Characteristics (Operational)
Temperature See Chapter 3 for air flow ambient temperatures.
Temperature change rate (maximum) 20°C/hr (36°F/hr)
Relative humidity 10–95% noncondensing
Maximum wet bulb 32°C (90°F)
Minimum dew point 2°C (36°F)
1–2

System Summary
Tables 1–2 and 1–3 show the configuration performance metrics for the
Alpha processor type, clock frequency, and cache. All benchmarks were
performed using the Digital UNIX operating system.
Table 1–2 SPECint92, SPECfp92, Dhrystone VI, and Whetstone Performance Metrics
Alpha
Processor Clock Frequency Cache SPECint92 SPECfp92 Dhrystone VI Whetstone
DECchip 21066 166 MHz 1 MB 15 ns 76.05 86.59 333,374 178,500
DECchip 21066A 233 MHz 1 MB 15 ns 91.23 107.83 263,012 249,900
Table 1–3 Rhealstone Performance Metrics
Alpha
Processor Clock Frequency Cache
Context
Switch
Time1Preemption Time1
Intertask
Message
Latency1Semaphore
Shuffle Time1
DECchip 21066 166 MHz 1 MB 15 ns 22.6 52.97 116.17 239.74
DECchip 21066A 233 MHz 1 MB 15 ns 18.6 44.02 93.83 189.57
1All Rhealstone results are reported in microseconds (
 sec).
Figure 1–1 identifies the MLB major components and connectors. The
main figure shows the AT style keyboard connector, and the breakout
figure in the top-left corner shows the configuration using the PS/2 style
keyboard and mouse connectors.
CAUTION: You must follow proper antistatic protection procedures whenever
you handle the MLB or its components. Failure to do so may
damage the components.
1–3

System Summary
Figure 1–1 Main Logic Board
MR-6391-AI
1–4

2PhysicalDescription
This chapter describes the following physical features of the Digital
AXPpci 33:
• Core module assembly
• Main logic board (MLB)
• Single inline memory modules (SIMMs)
• ISA option modules
• PCI option modules
2.1 Core Module Assembly
Figure 2–1 depicts a typical core module assembly consisting of:
• MLB
• DECchip 21066 processor
• Four SIMMs
• Socketed cache SRAMs
• PCI and ISA option modules
Not shown are any bulkhead connector adapters required for external
serial ports, parallel ports, and a SCSI port. Use the core module assembly
dimensions to size the overall module assembly for a specific enclosure.
2.2 Main Logic BoardThe MLB contains these sockets and connectors:
• Zero insertion force (ZIF) socket for a DECchip 21066 processor chip
• Sockets for cache
• Connector for the floppy disk controller (FDC)
• Connector for the integrated device electronics (IDE) disk controller
• Connector for the SCSI controller
• Connector for the parallel port
• Connectors for two serial ports
• Connectors for the keyboard/mouse controller
• Connectors for the memory subsystem, which supports four SIMMs
2–1

Physical Description
Figure 2–1 Core Module Assembly Outline
MR-6399-AI
• Connectors for the PCI and ISA option modules
• Connectors for the light emitting diodes (LEDs)
• Connector for the Reset switch
• Connector for the speaker
All MLB sockets and connectors are on side 1.
2.2.1 Physical Mounting
The AXPpci 33 MLB is a standard Baby–AT form factor with the addition
of three 0.157 inch diameter ‘‘B’’ holes. The ‘‘B’’ holes are module tooling
holes used during manufacturing. As shown in Figure 2–2, nine 0.157
inch diameter holes and one 0.157 inch x 0.256 inch slot are available for
securing the MLB to the chassis. The maximum screw-head diameter or
stand-off diameter used in any hole is 0.380 inches. An exception is the
2–2