Compaq AlphaServer DS20 Systems
Technical Summary
System Overview
Features and Benefits
System Block Diagram
System Board
RAID (Redundant Array of Independent Disks)
Split Bus StorageWorks Shelf
Server Management
Operational Management
Platform Management
Error Reporting
Reliability and Availability Features
Component and Connector Locations
Processor Features
Third-Generation Alpha Chip
Chip Operation
Alpha 21264 Features
Processor Module
Memory Features
I/O Features
System Features
Processor Configuration Rules
Installation and Maintenance
Security Features
Memory Options
Memory Configuration Rules
PCI to Memory Channel Interconnect
Operating System Support
System I/O
I/O Configuration Rules
I/O Implemenation
System Control
Service and Support
Sources of Performance Information
Information for COMPAQ Partners
Hardware Warranty
Software Warranty
Compaq AlphaServer DS20 System Diagrams
System Features at a Glance
Physical Characteristics
Compaq AlphaServer DS20 Systems
The Compaq AlphaServer DS20 system delivers high
of tomorrow. You can choose from three popular operating
performance for business, technical, and scientific
environments— DIGITAL UNIX , Windows NT, and OpenVMS
applications at an affordable price. As a high-capacity
operating systems  as well as thousands of applications.
database server, high-performance application server,
The AlphaServer DS20 system integrates into your current
Network File System (NFS) server, or Internet server, the
operating environment and anticipates future needs with
AlphaServer DS20 delivers exceptional value and
upgrade capabilities.
investment protection.
More information on Compaq AlphaServer DS20 systems
The 64-bit Alpha RISC architecture, at the heart of DIGITAL
is on the World Wide Web:
AlphaServer products, and now Compaq AlphaServer
products, provides fast processing and quick response for
today’s applications and will run the advanced applications
System Overview
The Compaq AlphaServer DS20 introduces the thirdgeneration Alpha processor, the Alpha 21264, in a pedestal
system that offers twice the performance of a comparable
speed EV56 Alpha chip. The switch-based system
interconnect exploits the full potential of the 21264 chip.
The system is available with one or two processors (500
MHz), each with a 4-MB ECC cache. The pedestal system
offers up to 10 internal storage devices, including a floppy
diskette drive, a CD-ROM, one additional 5.25-inch removable
media device, and seven hot-swap StorageWorks wide disk
drives. The system supports up to 128 GB of internal storage
using 18.2 GB disks.
The AlphaServer DS20 offers the following high-reliability
features: heat sensor, fan status and power supply sensors, and
ECC memory. Integrated on the system board are controllers
for two SCSI devices, a diskette, two serial ports, one parallel
port, and the keyboard and mouse.
Three operating systems are supported: DIGITAL UNIX,
OpenVMS, and Microsoft Windows NT Server. Customers
can order the system that meets their present application needs;
they choose the size of the system disk, two SCSI channels,
and an ethernet adapter. Systems can also be configured in a
choice of two cabinet enclosures: a 67-inch or 79-inch Mseries cabinet.
Features and Benefits
Leadership 64-Bit Architecture
The Alpha 64-bit architecture was introduced with the Alpha
21064 chip in 1992 and now the 21264, builds upon that
proven architecture.
The Alpha 21264 chip when combined with a switch-based
interconnect demonstrates its full potential. This switch-based
system provides a memory bandwidth of up to 5.2 Gbytes/sec
(peak) using two 256-bit memory buses running at 83 MHz.
Outstanding Value
The world’s fastest microprocessor is now offered in a lowend server. Use it to validate the performance that can be
achieved with the new Alpha 21264.
Reliability and Availability
The AlphaServer DS20 uses the latest technologies to achieve
redundancy, error correction, and fault management. The
balance between simple error detection and error correction
provides high availability at low cost.
Driving the design for this system was the objective to
maximize the potential of the Alpha 21264 chip. Rather than
implementing the traditional bus interconnect, the system
designers moved to a switch-based interconnect system. With
a bus design, the processors, memory, and I/O modules must
share the bus. As the number of bus users increases, the
bandwidth is used up. However, with a switch-based system
there is no degradation in performance as the number of CPUs,
memory, and I/O users increase. Although the users increase,
the speed is maintained.
C-chip. Provides the interface from the CPUs and main
memory. Although there is only one in the system, it
allows each CPU to do transactions simultaneously.
D-chips. Provide the data path for the CPUs, main
memory, and I/O.
P-chips. Provide the interface to two independent 64-bit
PCI buses.
The DS20 system supports up to two CPUs and up to 4 Gbytes
memory in 16 DIMM slots. Each memory option contains
four DIMMs, so each bank has four DIMMs.
Two 256-bit memory buses support four memory arrays.
Transactions are ECC protected. Upon the receipt of data, the
receiver checks for data integrity and corrects any errors.
Commands and addresses are parity protected.
With a switch-based, or point-to-point interconnect, the
performance remains constant, even though the number of
transactions multiplies. The switched system bus is made
possible through the use of a set of complex chips that route
the traffic over multiple paths. The chipset consists of one
C-chip, two P-chips, and eight D-chips.
The system bandwidth is 5.2 Gbytes/sec.
Command, Address, and Control lines for each Memory Array
C chip
Control lines for D chips
P chip
64 bit PCI
P chip
64 bit PCI
1 or 2
8 D chips
1 or 2
B cache
B cache
System Block Diagram
System Board
The interconnect switch is implemented on the system board
by the chipset consisting of one C-chip, two P-chips, and eight
D-chips. This complex chipset provides the data and address
path between the CPUs, memory, and the I/O subsystem.
Connectors are provided for the following:
2 CPU modules
16 DIMM memory modules
6 PCI devices
1 ISA device
1 floppy diskette drive
I/O panel for parallel port, COM1 and COM2 ports, keyboard
and mouse
A flash ROM holds the AlphaBIOS console code, the SRM
console code, and the NVRAM data.
Integrated into the system board are controllers for the floppy
diskette, two serial ports, one parallel port, and keyboard and
DIMM Slots
Parellel Port
Keyboard & Mouse
DIMM Slots
PCI 0 Slot 7
PCI 0 Slot 8
Firmware Flash ROM
PCI 0 Slot 9
PCI 1 Slot 7
PCI 1 Slot 8
PCI 1 Slot 9
ISA Slot
Component and Connector Locations
Third-Generation Alpha Chip
The Alpha 21264 microprocessor (EV6) is a superscalar
superpipelined implementation of the Alpha architecture. The
Alpha 21264 chips are manufactured using state of the art
CMOS-6 process, using a feature size of 0.35 micron. Over
15.2 million transistors are on one die.
Designed for performance, the 21264 achieves this goal by
carefully studied and simulated architectural and circuit
analysis. The 21264 memory system also enables the high
performance levels. On-chip and off-chip caches provide for
very low latency data access, which allows for very high
bandwidth data access. The large, off-chip cache—4 MB—
runs at 200 MHz.
Internal to each chip is a 64-Kbyte instruction cache (I-cache)
and a 64-Kbyte data cache (D-cache).
• I-cache. 64 Kbytes, two-way set-associative, virtually
addressed cache with 64-byte blocks
• D-cache. 64 Kbytes, two-way set-associative, virtually
indexed, physically tagged, writeback cache with 64-byte
Chip Operation
Several key design choices were made in the EV6 architecture
to maximize performance: Four instructions are fetched each
cycle, and then how those instructions are handled boosts the
speed of execution. Register renaming assigns a unique
storage location with each write reference to a register,
avoiding register dependencies that can be a potential
bottleneck to processor performance.
Alpha 21264 Features
Out-of-order instruction execution
Large (64 Kbyte) on-chip data and instruction caches
Improved branch prediction through intuitive execution
Register renaming
Increased bandwidth for high-speed access to second-level
cache and system memory
Motion video instructions
Square root and divide instructions
All instructions are 32 bits long and have a regular
instruction format
Floating-point unit, supports DIGITAL and IEEE floatingpoint data types
80 integer registers, 64 bits wide
72 floating-point registers, 64 bits wide
Processor Module
An AlphaServer DS20 can have one or two CPU modules.
In addition to the Alpha 21264 chip, the CPU module has a
4-Mbyte second-level cache and a 2.2V DC to DC converter
with heatsink that provides the required voltage to the Alpha
chip. Power-up diagnostics are in a flash ROM on the module.
Cooling of the microprocessor chip is provided by a fan on the
chip heatsink, as shown here.
Out-of-order execution implies that instructions can execute in
an order that is differnet from the order that the instructions are
fetched. In effect, instructions execute as soon as possible.
This allows for faster execution since critical path
computations are started and completed as soon as possible.
In addition, the 21264 employs speculative execution to
maximize performance. It speculatively fetches and executes
instructions even though it may not know immediately whether
the instruction will be on the final execution path. This is
particularly useful, for instance, when the 21264 predicts
branch directions and speculatively executes down the
predicted path. The sophisticated branch prediction in the
21264 coupled with the speculative and dynamic execution
extracts the most instruction parallelism from applications.
Processor Configuration Rules
The first CPU module is installed in CPU slot 0. The second
CPU is installed in CPU slot 1.
For more information about the chip, see:
System I/O
The switch interconnect can move a large amount of data over
two independent memory data buses. Each memory bus is 256
bits wide (32 bytes). The memory bus speed is 83 MHz. This
yields 2.67 GB/sec bandwidth per bus (32 x 83 MHz = 2.6
GB/sec). With two CPUs the bandwidth becomes 5.2 GB/sec.
There are two 64-bit PCI buses. Industry-standard PCI I/O
buses allow you to use inexpensive, widely available I/O
options. Both 32-bit and 64-bit PCI options can be used.
Six slots can be used for PCI controllers, or five slots for PCI
and one slot for an ISA option.
Memory throughput in this system is maximized by the
following features:
• Two 256-bit wide memory data buses
• Very low memory latency (120 ns) and high bandwidth
with 12 ns clock
• Numerous reliability and availability features, such as
ECC memory and command/address parity
Memory Options
Each memory option consists of four 200-pin DIMM modules.
The DIMMs are synchronous DRAMs. Each system supports
up to four memory options (16 DIMMs) for a total of 4
gigabytes of memory. The options run at a speed of 83 MHz.
Memory options are supported in the following sizes:
• 128 Mbytes
• 256 Mbytes
• 512 Mbytes
• 1 Gbyte
Memory Configuration Rules
A memory option consists of four DIMMs, and all four
DIMMs must be the same size.
Convention places the largest memory option in slots
marked 0 on the system board.
Other memory options can be the same size or smaller
than the first memory option.
Memory options must be installed in slots designated for
each bank. The first bank goes into slots marked 0, the
second bank into slots marked 1, and so on.
The industry-standard PCI bus is the number one choice for
high-performance I/O options, such as disk storage and highperformance video applications.
The PCI bus implementation has the following characteristics:
• Fully compliant with the PCI Version 2.1 Specification
• Operates at 33 MHz, delivering a peak bandwidth of 500
MB/sec; over 250 Mbytes/sec for each PCI bus
• Supports 6 option slots
• Supports peer-to-peer I/O operations
• Supports three address spaces: PCI I/O, PCI memory, and
PCI configuration space
• Supports byte/word, tri-byte, and longword operations
• Exists in noncached address space only
The Adaptec 7895 chip provides the bridge from PCI to SCSI,
providing two separate devices to the PCI bus. (Today only
Windows NT can use the integral SCSI adapters.) Two ports
that support UltraSCSI devices are offered.
The ISA bus provides system support functions and the use of
peripheral devices. An ISA connector is available for devices
that provide functions not offered in a PCI implementation.
The Cypress SIO chip, which provides the bridge between the
PCI bus and the ISA bus, incorporates the logic for the
• ISA interrupt controller
• Speaker driver
• Decoding and control for utility bus peripheral devices
• IDE interface
This system does not support IDE devices.
I/O Configuration Rules
A graphics adapter, if present in the system, must be installed
in PCI 0.
I/O Implementation
Two separate 64-bit PCI buses are provided, each with three
slots. As can be seen in the block diagram, the C-chip controls
both PCI control chips.
At the rear of the system are connectors offering access to two
serial communications ports, one parallel port, and ports for
the keyboard and mouse. Two breakouts are also on the back
PCI 0 offers the following:
• Slots for three PCI devices or two PCI devices and one
ISA device
• Integrated control for system functions and bulkhead ports
• Integrated control for two IDE ports and a universal serial
PCI 1 offers three PCI slots.
PCI Bus 0
P-chip 0
ISA Slot
Flash ROM
(NVRAM functions)
SCSI device
SCSI device
PCI Slot
P-chip 1
PCI Slot
PCI Bus 1
Block Diagram of I/O Control
System Control
The server feature card is located in the compartment to the
right of the system board. This module provides for the
• Remote server management
• Environmental monitoring
• Power system event data collection
The AlphaServer DS20 system offers up to 10 internal storage
devices including a CD-ROM drive, floppy diskette drive, one
additional 5.25-inch removable media device, and seven hotswap StorageWorks disk drives. The system supports up to
128 Gbytes of internal storage (using 18.2 GB disks). The
StorageWorks shelf is 16-bit (wide) UltraSCSI.
RAID (Redundant Array of Independent Disks)
The system can be configured with optional PCI RAID
controllers to organize disk data cost-effectively, improve
performance, and provide high levels of storage integrity.
The optional RAID controllers have the following features:
• Support for hot-swap drives
• Automatic rebuild after hot swap
• Console support for booting system from RAID
• RAID levels 0, 1, 0+1, 5
• Optional write cache
• Optional read cache
• Support for command queuing
Split Bus StorageWorks Shelf
The StorageWorks shelf can be reconfigured as two SCSI
buses by installing a second repeater card. The card is part of
the UltraSCSI Bus Splitter Kit (H8253-AA).
Server Management
The AlphaServer products support important operational and
platform management requirements.
Operational Management
Server/Network Management. ServerWORKS Manager software is included with each system. This software utilizes the
Simple Network Management Protocol (SNMP) environment
to assist the network or server administrator by constantly
monitoring the network for problems, thus avoiding expensive
downtime. The software monitors vital server information,
such as CPU and file system utilization, as well as the condition of the network supported by the management console.
Remote Server Management. An integral remote console
manager (RCM) lets the administrator perform several tasks
from a serial console: monitor the system power, temperature,
and fans, and reset, halt, and power the system on or off,
regardless of the operating system or hardware state.
These systems support all the management tools and features
provided by the operating systems to manipulate and monitor
system resources such as disks, printers, networks, and backups.
Platform Management
The AlphaServer DS20 systems support platform management
tasks such as manipulating and monitoring hardware
performance, configuration, and errors. For example, the
operating systems provide a number of tools to characterize
system performance and display errors logged in the system
error log file.
In addition, system console firmware provides hardware
configuration tools and diagnostics to facilitate quick hardware
installation and troubleshooting. The system operator can use
simple console commands to show the system configuration,
devices, boot and operational flags, and recorded errors. Also,
the console aids in inventory support by giving access to serial
numbers and revisions of hardware and firmware.
Error Reporting
Compaq Analyze, a diagnostic tool used to determine the
cause of hardware failures, is installed with the operating
systems. It provides automatic background analysis, as it
constantly views and reads the error log file. It analyzes both
single error/fault events and multiple events. When an error
condition is detected, it collects the error information and
sends it and an analysis to the user. The tool requires a
graphics monitor for its output display.
Reliability and Availability Features
The AlphaServer DS20 system achieves an unparalleled level
of reliability and availability through the careful application of
technologies that balance redundancy, error correction, and
fault management. Reliability and availability features are
built into the CPU, memory, and I/O, and implemented at the
system level.
Processor Features
CPU data cache provides error correction code (ECC)
• Parity protection on CPU cache tag store.
• Multi-tiered power-up diagnostics to verify the
functionality of the hardware.
With two processors, when you power up or reset the system,
each CPU, in parallel, runs a set of diagnostic tests. If any
tests fail, the failing CPU is configured out of the system.
Responsibility for initializing memory and booting the console
firmware is transferred to the other CPU, and the boot process
continues. This feature ensures that a system can still power
up and boot the operating system in case of a CPU failure.
Messages on the operator control panel power-up/diagnostic
display indicate the test status. and component failure
Memory Features
The memory ECC scheme is designed to provide
maximum protection for user data. The memory scheme
corrects single-bit errors and detects double-bit errors and
total DRAM failure. It also detects RAM address errors.
Memory failover. The power-up diagnostics are designed
to provide the largest amount of usable memory, configuring around errors.
I/O Features
ECC protection on the switch interconnect and parity
protection on the PCI and SCSI buses.
Extensive error correction built into disk drives.
Optional internal RAID improves reliability and data
Disk hot swap on systems configured with RAID.
System Features
Auto reboot. On systems running DIGITAL UNIX or
OpenVMS, a firmware environment variable lets you set the
default action the system takes on power-up, reset, or after an
operating system crash. For maximum system availability, the
variable can be set to cause the system to automatically reboot
the operating system after most system failures. Windows NT
auto reboots by default, but lets you specify a countdown value
so you can stop the system from booting if you need to carry
out other tasks from the console firmware.
Software installation. The operating systems are factory
installed. Factory installed software (FIS) allows you to boot
and use your system in a shorter time than if you install the
software from a distribution kit.
Diagnostics. During the power-up process, diagnostics are run
to achieve several goals:
• Provide a robust hardware platform for the operating
system by ensuring that any faulty hardware does not
participate in the operating system session. This maximizes system uptime by reducing the risk of system
• Enable efficient, timely repair.
The system has a built-in firmware update utility (LFU) that
provides update capability for console and PCI I/O adapter
firmware. A fail-safe loader provides a means of reloading the
console in the event of corrupted firmware.
Thermal management. The air temperature and fan operation
are monitored to protect against overheating and possible
hardware destruction. Two fans in the front of the enclosure
cool the system box, and additional cooling is provided in the
rear to cool the StorageWorks disks. In addition, each
processor has its own fan on the chip heatsink. If a processor
fan or fan in the front of the box fails, the system will shut
Error handling. Parity and other error conditions are detected
on the PCI and ISA buses. The memory checking scheme
corrects single-bit errors and detects double-bit errors.
Multiple ECC corrections to single-bit errors detected by the
operating systems help in determining where in the system the
error originated. Errors are logged for failure analysis.
Disk hot swap. The hardware is designed to enable hot swap
of disks. Hot swap is the removal of a disk or disks from any
of the storage compartments while the rest of the system
remains powered on and continues to operate. This feature
contributes significantly to system availability. Since many
disk problems can be fixed without shutting down the entire
system, users lose access only to the disks that are removed.
N+1 power redundancy A second power supply can be added
to provide redundant power to the system box.
An external UPS can be used to support critical customer configurations. Because power is maintained for the entire system
(CPU, memory, and I/O), power interruptions are completely
transparent to users.
Installation and Maintenance
The systems are designed for easy hardware, software, and
option installation. Options ordered with a system are
preinstalled and tested at the factory. The operating systems
are also installed at the factory.
Installation of the pedestal system is relatively simple, and
may take only 30 minutes.
Security Features
A key lock controls access to the StorageWorks disk area,
and when locked, the panels covering the system cannot
be removed.
A security loop on the rear of the system allows the
system to be secured in place.
An interlock sensor switch shuts down power if the top
cover is removed while power is on.
A cluster is a loosely coupled set of systems that behaves (is
addressed and managed) like a single system, but provides
high levels of availability through redundant CPUs, storage,
and data paths. Clusters are also highly scalable, meaning that
CPU, I/O, storage, and application resources can be added
incrementally to efficiently grow capacity. For customers, this
translates to reliable access to system resources and data, and
investment protection of both hardware and software.
Clustering allows multiple computer systems to communicate
over a common interface, share disks, and spread the
computing load across multiple CPUs. Clustering is implemented using our traditional interconnects and using the
newest technology.
PCI to Memory Channel Interconnect
Under DIGITAL UNIX and OpenVMS, you can build highavailability clusters using the PCI to Memory Channel
interconnect. The Memory Channel interconnect is a highbandwidth, low-latency PCI-based communications
interconnect for up to eight AlphaServer systems. Data written
to one computer’s memory is shared by other computers on the
Memory Channel bus.
Operating System Support
For clustered UNIX systems, TruCluster Software solutions
allow users access to network services and provide further
failover recovery from server, network, or I/O failures. UNIX
cluster systems use the SCSI bus and/or PCI to Memory
Channel interconnect bus between disks and systems.
OpenVMS cluster systems use the CI, SCSI, Ethernet, FDDI,
DSSI, and Memory Channel as the interconnect between disks
and systems. OpenVMS systems can be configured into DSSI
clusters using the following two options:
• The KFPSA DSSI adapter, which gives the system the
capability of creating DSSI clusters.
• The HSD family of storage controllers.
Windows NT cluster systems use SCSI buses and Ethernet.
The primary means of clustering AlphaServer DS20 systems
depends on the operating system.
• CI clusters, OpenVMS only
• Memory Channel, DIGITAL UNIX and OpenVMS
• SCSI clusters, DIGITAL UNIX, OpenVMS, and
Windows NT
• DSSI clusters, OpenVMS only
The PCI CCMAB adapter is the interface between a PCI and a
Memory Channel bus. This bus is a memory-to-memory
computer system interconnect that permits I/O space writes in
one computing node to be replicated into the memories of all
other nodes on the Memory Channel bus. A write performed
by any CPU to its reflected address region will result in
automatic hardware updates to memory regions in other nodes.
One node’s write is “reflected” to other nodes as a direct side
effect of the local write. This provides a memory region with
properties similar to a high-performance shared memory
across a group of nodes.
COMPAQ has an ongoing program of performance
engineering, using industry-standard benchmarks that allow
comparisons across major vendors’ systems. These
benchmarks against competitive systems are based on
comparable CPU performance, coupled with comparable
memory and disk expandability.
See Table 1 for the record-breaking performance numbers of
the AlphaServer DS20 systems. For example:
SPECweb96 Internet Server — 6,065 operations per
second, using an AlphaServer DS20 UNIX system with
two processors, and 4,092 ops/sec with a single processor.
The SPECweb96 benchmark focuses on server performance
for static Web pages, measuring the ability of the server to
service HTTP requests or “gets.” One or more clients are used
by SPECweb96 to send the HTTP requests to the Web server.
The software then measures the response time for each
request. At the end of the benchmark run, SPECweb96
calculates a metric based on overall throughput, measured as
maximum benchmark operations per second.
System performance, however, is highly dependent upon
application characteristics. Thus, benchmark information is
one helpful “data point” to be used in conjunction with other
purchase criteria such as features, service, and price.
Sources of Performance Information
Performance information is available on the internet, and you
can have it delivered directly to your fax machine.
InstaFACTS. The InstaFACTS fax service delivers
information directly to your fax machine. Call 1-800DIGITAL (via a touch-tone phone in the U.S.A. and
Canada) and 908-885-6426 (outside the U.S.A. and
Canada). A catalog of documents is available from which
you can order an abbreviated table of performance
information, including performance briefs and flashes,
TPC results, AIM results, and graphics results.
FTP. Access performance documents from
The directory is pub/DEC/DECinfo/performance/sys.
World Wide Web. The document URL is
Information for COMPAQ Partners
COMPAQ and its partners and customers can register with
DIGITAL Business Link to access information needed to
purchase and sell COMPAQ products and services; including
access to pricing, product, sales, and marketing information.
Also see the Alliances and Partners Web site located at
Service and Support
COMPAQ provides a comprehensive set of services that
range from migration, consulting, and training, to direct
support of Alpha systems, software, and applications. For
information on COMPAQ Services, point your Web browser
Hardware Warranty
The AlphaServer DS20 system and components, including
CPU, memory, PCI controllers, and power supplies, have a 3year onsite, 5-day per week, 9-hour per day hardware warranty
with next-day response time.
StorageWorks components contained in the pedestal or cabinet
systems are supported by the comprehensive StorageWorks
warranty: five years for disks, three years for controllers, two
years for tape devices, and one year for other components. The
first year includes onsite next-day response time. Network
products in the pedestal or cabinet systems carry the network
products warranty.
Users can upgrade to higher levels of service through a variety
of hardware supplemental services.
Software Warranty
The warranty for DIGITAL UNIX and OpenVMS is
conformance to SPD with advisory telephone support for
a period of 90 days. The warranty for Windows NT is
conformance to the written material accompanying the
software. Users can upgrade to higher levels of service
through a variety of software supplemental services.
AlphaServer DS20 System Diagrams
4. Floppy diskette drive
5. Control panel display
6. Control panel switches
1. StorageWorks shelf for hard disk drives
2. SCSI CD-ROM drive
3. Optional removable media drive bay
1. CPU modules
2. Server feature card
3. Memory DIMMs
4. PCI slots
5. SCSI breakouts
6. PCI/ISA bulkhead ports
7. Power inlet and power supply
8. Optional power inlet
9. Fan or optional power supply
10. Parallel port
11. Serial port (COM2)
12. Serial port (COM1)
13. Keyboard port
14. Mouse port
System Features at a Glance
Table 1 provides a quick reference to features of the Compaq AlphaServer DS20 systems.
Table 1 AlphaServer DS20 Features
CPU Features
Symmetric multiprocessing
CPU clock speed
Cache on chip
On-board cache
Upgradable in pedestal and cabinet
1–2 processors
Alpha 21264
500 MHz
64 KB I-cache
64 KB D-cache
4 MB
CPU, memory, I/O, storage
Memory (maximum)
4 GB
11,616 tpmC @ $50.58
1.44 MB diskette drive, CD-ROM drive, Ethernet controller, SCSI controller, 2 serial ports, 1 parallel
port, keyboard and mouse, integral remote system console, operating system license and customer
documentation, Internet software
Standard Features
2 CPUs
Internal Storage
Removable media
Maximum internal storage
Total storage
I/O slots
Maximum PCI throughput
CD-ROM, floppy diskette, one additional 5.25-inch removable media bay
7 hot swap disks (126 GB)
128 (18.2 GB each)
6 PCI slots (5 PCI and 1 PCI/ISA)
Over 500 MB/sec with two 256 MB/sec buses
Availability Features
OpenVMS clusters
UNIX TruClusters Solutions
Windows NT cluster
System auto reboot, thermal management, remote system management, RAID 0, 1, 0+1, 5, disk hot
swap, memory failover, ECC memory, ECC cache, N+1 power supply, SMP CPU failover, error
logging, optional uninterruptible power supply
CI, Ethernet, DSSI, SCSI, FDDI, PCI to Memory Channel Interconnect
SCSI, PCI to Memory Channel Interconnect
Ethernet, FDDI, SCSI
Operating Systems
DIGITAL UNIX, OpenVMS, Microsoft Windows NT Server
3-year, on-site
90-day telephone advisory support for OpenVMS and DIGITAL UNIX
Physical Characteristics
Table 2 details basic physical characteristics of the system.
Table 2 AlphaServer DS20 Physical Characteristics
Shipping Dimension
60 cm (23.8 in.)
43 cm (16.9 in)
65 cm (25.6 in)
43 kg (95 lb) typical; 71 kg (156 lb) maximum
Installed Dimensions
46 cm (18.1 in.)
35.8 cm (14.1 in.)
58.6 cm (23.1 in.)
39 kg (86 lb) typical; 51 kg (113 lb) maximum
75 cm (29.5 in.)
75 cm (29.5 in.)
15 cm (6 in.)
75 cm (29.5 in.)
75 cm (29.5 in.)
Relative humidity
Maximum wet bulb
Minimum dew point
Maximum heat dissipation
Single supply
Dual supply
Airflow and quality
Mechanical shock
Rate of change
Storage (60 days)
Rate of change
Storage (60 days)
Rate of change
Storage (60 days)
Storage (60 days)
2390 Btu/hr
4097 Btu/hr
Intake location
Exhaust location
Particle size
10−40° C (50−104° F)
11° C/hr (20° F/hr)
-40−66° C (-40−151° F)
-40−66° C (-40−151° F)
20° C/hr (36° F/hr)
28° C (82° F)
46° C (115°F)
2° C (36° F)
Not tested
3048 m (10,000 ft)
12192 m (40,000 ft)
10 G 10 ms
20 G peak 30 ms
10-500 Hz .1 G peak
1.03 Grms 5-300Hz
38 LpAm, dba
5.7 LwA, B
37 LpAm, dba
5.6 L , B
Electrical—Power supplies are universal 120/240 Vac
Nominal ac voltage
Operating Voltage range
Power source phase
Nominal frequency
Frequency range
Maximum inrush current
RMS current at nominal
voltage (steady state)
Single power supply
Dual power supply
Power cord
100-120 Vac
90-128 Vac
60 Hz
59-61 Hz
50 Amps
220-240 Vac
180-256 Vac
50 Hz
49-51 Hz
50 Amps
8.0 Amps
4.6 Amps each supply
U.S. plug
4.0 Amps
2.2 Amps each supply
IEC 320 C13
190 cm (75 in.)
NEMA 5-15
* Maximum operating temperature at Sea Level. Reduce by 1 C (1.8 F) for each 600 m (2000 ft) above Sea Level.
Higher altitudes are possible if maximum operating temperature is reduced (see Temperature, above); other restrictions may apply,
such as maximum permissible altitude for hard drives.
Features may differ among operating environments. Performance may vary
depending on configuration, application, and operating environment.
Compaq believes the information in this publication is accurate as of its
publication date; such information is subject to change without notice.
Compaq is not responsible for any inadvertent errors.
COMPAQ conducts its business in a manner that conserves the environment
and protects the safety and health of its employees, customers, and the
COMPAQ and the Compaq logo are trademarks or registered trademarks of
Compaq Computer Corporation: AlphaServer, DIGITAL, OpenVMS,
ServerWORKS, StorageWorks, and TruCluster are registered trademarks of
Digital Equipment Corporation.
Digital Equipment Corporation now owned by Compaq Computer
Microsoft, Windows, and Windows NT are registered trademarks of
Microsoft Corporation. SPECint95, SPECfp95, SPECfp95 SMP,
SPECint_rate95, SPECfp_rate95, and SPECweb96 are registered trademarks
of the Standard Performance Evaluation Corporation. UNIX is a registered
trademark in the United States and other countries, licensed exclusively
through X/Open Company.
Copyright © 1999 Compaq Computer Corporation.
All rights reserved.