DIGITAL Software Product Description ___________________________________________________________________ PRODUCT NAME: DECnet[TM] SNA Gateway for SPD 25.C6.05 Synchronous Transport, Version 1.3 DESCRIPTION DECnet[TM] SNA Gateway for Synchronous Transport (DECnet SNA Gateway- ST) is a member of the DECnet SNA Gateway product family. This family consists of hardware and software products that allow users to exchange information and share resources bidirectionally between suitably configured DIGITAL[TM] systems in a DECnet environment and IBM[R] systems in a Systems Network Architecture (SNA) environment. Users on one or more DIGITAL systems can simultaneously perform functions such as accessing IBM application programs or other system resources, act as a 3270 display station, perform data transfer between DIGITAL and IBM file systems, exchange electronic documents and mail messages, submit jobs to IBM batch subsystems acting as a Remote Job Entry workstation, and implement distributed, task-to-task application programs that run between DIGITAL and IBM systems. The DECnet SNA Transport product set provides a means of connecting DECnet and SNA networks that can be used by a wide variety of DIGITAL- supplied access routines running on OpenVMS[TM] Alpha and OpenVMS VAX[TM] operating environments. DECnet SNA Gateway-ST is managed and config- ured using the DECnet SNA gateway management software that is part of the DECnet SNA Gateway-ST product. For additional information on the various access routines and their capabilities, see the Optional Soft- ware section of this Software Product Description. August 1998 AE-JE94F-TE DECnet SNA Gateway-ST works with either of the DEC[TM] MicroServer hard- ware platforms. The DEC MicroServer (DEMSA-S*) provides connectivity for up to four synchronous lines and the DEC MicroServer-SP (DEMSB- S*) provides a single synchronous line connection. (Note: In this doc- ument, the term "DEC MicroServer" refers to either hardware device, unless specifically stated otherwise. Both hardware devices are re- tired but are still supported.) DECnet SNA Gateway-ST is part of both the DECnet and the SNA networks. Architecturally, it is a DECnet end node implementation to DECnet and a Physical Unit (PU) Type 2.0 to SNA. It provides bidirectional net- work access between DECnet and SNA networks. The DEC MicroServer pro- vides physical connectivity to an Ethernet local area network (LAN) and, when used in conjunction with DECnet SNA Gateway-ST software, it provides SNA connectivity to the DECnet network. This product can be used in networks currently using other DECnet SNA Gateway systems and can share access routines, Ethernet LANs, and load host resources with those systems. DECnet SNA Gateway-ST software is downline loaded into the DEC MicroServer system. The gateway management software, which is part of the DECnet SNA Gateway-ST, is required for the OpenVMS node designated as the load host for DECnet SNA Gateway-ST. Other DECnet systems wishing access to the SNA network through the DEC MicroServer should be configured with the appropriate DECnet SNA access routines. DECnet SNA Gateway-ST V1.3 supports SNA synchronous communications us- ing the SDLC protocol. The number of links supported depends on the hardware unit being used (DEC MicroServer or DEC MicroServer-SP), line speeds required by the customer, and the electrical interface used. Table 1 shows the configuration matrix for connecting to the SNA net- work. 2 Table 1: Number of Synchronous Lines Supported ___________________________________________________________________ Maximum Line Speed (Kbps) Electrical Interface 19.2 56/64 128 256 ___________________________________________________________________ DEC MicroServer RS232-D/V.24 4 - - - V.35 4 4 2 1 DEC MicroServer-SP RS232-D/V.24 1 - - - ___________________________________________________________________ Lines connected to the DEC MicroServer or DEC MicroServer-SP should be configured according to guidelines specified in the DECnet SNA Gateway- ST user documentation. Loading DECnet SNA Gateway-ST Software The DEC MicroServer requires software to be loaded into memory before DECnet SNA Gateway operation. DECnet SNA Gateway-ST software is down- line loaded into the hardware across the Ethernet LAN from an OpenVMS Alpha or OpenVMS VAX system acting as a DECnet load host system. Most Alpha, VAX, MicroVAX[TM], VAXstation[TM], VAXserver[TM], DECsystem[TM], and DECstation[TM] systems running Open-VMS software are supported as Ethernet load hosts for DECnet SNA Gateway-ST. Supported OpenVMS configurations are described in the OpenVMS Operating System for Alpha and VAX Software Product Description (SPD 25.01.xx). DECnet SNA Gateway Management Software DECnet SNA gateway management software, which is part of the DECnet SNA Gateway-ST, provides configuration and management functions for use with the DECnet SNA Gateway for Synchronous Transport V1.3 or higher. This management software allows the gateway administrator to config- ure the software executing in the DECnet SNA Gateway-ST system. The 3 administrator can set up parameters relating to lines, circuits, phys- ical units, logical units, and other key variables necessary for network- to-network communications between the DECnet and SNA networks. In ad- dition, the software allows the administrator to manage and diagnose problems related to the DECnet SNA Gateway-ST. DECnet SNA gateway management software is required on the DIGITAL load host node for DECnet SNA Gateway-ST. It must also be present on any other OpenVMS node where users want to manage DECnet SNA Gateway-ST and the DEC MicroServer. It is strongly recommended that the software also be installed on OpenVMS systems in order to facilitate debugging functions where IBM Interconnect application programs are developed using the DECnet SNA Programming Interface products. Gateway management software includes DECnet style network management tools for configuring, controlling, monitoring, and troubleshooting the DECnet SNA Gateway-ST product. These activities are generally per- formed by the DIGITAL system manager responsible for the designated load host node. Most management functions are performed from a node on the DIGITAL network rather than at or on the Gateway itself. Management of the DECnet SNA Gateway-ST should be viewed as part of the DIGITAL environment, while management of the synchronous circuits connecting the DECnet SNA Gateway to the IBM network is a joint re- sponsibility of the IBM and Digital system managers. (See the Customer Responsibilities section of this Software Product Description for more information.) DECnet SNA gateway management software allows a DIGITAL system oper- ator to bootstrap or restart a DECnet SNA Gateway remotely and pro- vide configuration and initialization facilities for the DECnet SNA Gateway. Problem Isolation and Determination Tools for the Gateway In addition to event logging and error counters, a wide range of fault isolation tools are included. 4 Trace capabilities SNATRACE and NETTRACE for OpenVMS are provided with the DECnet SNA Gateway-ST to help debug application programs as well as assist in identifying system problems. An operator can run a trace at the Circuit, Physical Unit (PU), or Session level, and then for- mat the data on a specified DIGITAL system. The trace features are help- ful in identifying an error for remedial action. A snapshot monitoring utility is provided to display on a DIGITAL host- controlled terminal the status of the Gateway's buffer availability, the number of SNA sessions currently in progress, and other informa- tion that pertains to both the DECnet and SNA network. If an irrecoverable error should occur during operation of the DECnet SNA Gateway system, a memory image may be dumped to a designated Ethernet-attached Alpha or VAX host. This memory image may then be pro- vided to your DIGITAL support personnel for problem diagnosis. Features o NRZI support - Signaling mode for the line(s) from the Gateway to the IBM system can be set to NORMAL or NRZI (non-return-to-zero- inverted) so that line characteristics match those set in the IBM ACF/NCP LINE macro. o Support for FULL duplex transmission - Circuits can be set FULL du- plex to allow data to be sent and received simultaneously on full duplex lines. This setting corresponds to DATMODE=FULL in the IBM ACF/NCP PU macro. o Support for RECFMS - The Gateway can send Record Formatted Main- tenance Statistics (RECFMS) messages to the IBM system. These mes- sages contain counters requested by the IBM Network Problem Deter- mination Application (NPDA) using Request Maintenance Statistics (REQMS) messages. Not all RECFMS messages are supported by the Gate- way. Refer to the DECnet SNA Gateway-CT and -ST Management user doc- umentation for more information. 5 o A simplified configuration procedure - After installing Gateway- ST gateway management software, a single configuration procedure is run which creates command procedures that define items for the DECnet database on the load host, and the SNA and DECnet databases on the Gateway. o Extended SDLC - Support for Extended Response Mode SDLC (Modulo 128). When Using DEC MicroServer Hardware o Synchronous line support - DECnet SNA Gateway-ST supports up to four SDLC connections at speeds of 64 Kbs/circuit or less, two connec- tions at 128 Kbs/circuit, or a single connection at 256 Kbs. o Session support - DECnet SNA Gateway-ST supports up to 128 concur- rent (Logical Unit) sessions for selected access routines. When Using DEC MicroServer-SP Hardware o Synchronous line support - DECnet SNA Gateway-ST supports one SDLC connection at up to 19.2 Kbps. o Session support - DECnet SNA Gateway-ST supports up to 32 concur- rent (Logical Unit) sessions for selected access routines. INSTALLATION DIGITAL requires that a customer's first purchase of this software prod- uct include DIGITAL Installation Services (QSF01-SZ). These services provide for installation of the software product by an experienced DIG- ITAL installation specialist. Customer Responsibilities Before installation of the software, the customer must: o Previously have installed all requisite hardware, including ter- minals. o Obtain, install, and demonstrate as operational any modems and other equipment and facilities necessary to interface to DIGITAL's com- munications equipment. 6 o Demonstrate equivalence of operation for modems other than Bell[TM] System 201C, 208A, or 209A; IBM 5866 Model 1; AT&T[R] 2596, 2556, Data Phone[R] II, (2096A, Digital 2500, or equivalent) type modems; or, in Europe, PTT-approved modems. o Have generated, to DIGITAL's satisfaction, any necessary IBM host software that will be communicating with the DECnet SNA Gateway- ST. o Have completed any additional requirements as described in the Ori- entation/Installation Service. o Make available for a reasonable period of time, as mutually agreed by DIGITAL and the customer, all hardware, communications facil- ities, and terminals that are to be used during installation. o Be prepared to work with the DIGITAL and the IBM system manager in the preinstallation activities outlined in the Orientation/Installation Service. o Be prepared to modify IBM component generation parameters to sup- port DECnet SNA Gateway-ST. Delays caused by any failure to meet these responsibilities will be charged at the then prevailing rate for time and materials. HARDWARE REQUIREMENTS In Ethernet LANs o Alpha, VAX, MicroVAX, VAXstation, VAXserver, DECstation, or DEC- system configuration as specified in the OpenVMS Operating System for Alpha and VAX Software Product Description (SPD 25.01.xx) o DEC MicroServer (DEMSA-Ax or DEMSB-Ax) and appropriate adapter ca- bles o Bell System compatible modems as listed in the Customer Responsi- bilities section, or, in Europe, PTT-approved modems 7 Processors Supported For information about supported processors, refer to the OpenVMS Op- erating System for Alpha and VAX Software Product Description (SPD 25.01.xx). Processors Not Supported MicroVAX I[TM], VAXstation I, VAX-11/725[TM], VAX-11/730, VAX-11/750, VAX-11/780, VAX-11/782, VAX-11/785, VAXstation 8000 Processor Restrictions A TK50 tape drive is required for stand-alone MicroVAX 2000 and VAXstation 2000 systems. Other Requirements DECnet SNA Gateway-ST needs at least one DECnet Phase IV node on the same Ethernet local area network (LAN) to act as a load host. The load host must be an OpenVMS Alpha or OpenVMS VAX system. Every load host on which the DECnet SNA Gateway-ST software is installed must contain: o A valid system configuration for the relevant operating system and the appropriate DECnet-Plus product. (Refer to the DECnet-Plus and OpenVMS Operating System for Alpha and VAX Software Product Descrip- tions for more information.) o A supported connection on the same Ethernet LAN as DECnet SNA Gateway- ST o An appropriate device available to read the software during instal- lation - Magnetic tape, TK50 drive, or CD-ROM Disk Space Requirements (Block Cluster Size = 1) Disk space required for installation: OpenVMS Alpha 5,185 blocks (2,593 KB) OpenVMS VAX 5,185 blocks (2,593 KB) 8 Disk space required for use (permanent): OpenVMS Alpha 3,536 blocks (1,768 KB) OpenVMS VAX 2,674 blocks (1,337 KB) These counts refer to the disk space required on the system disk. The sizes are approximate; actual sizes may vary depending on the user's system environment, configuration, and software options. In addition to disk space allocated to DECnet SNA Gateway-ST software, some disk space (approximately 5,000 blocks) should be reserved for any dump files that may be generated by DECnet SNA Gateway-ST. The lo- cation of these dump files is determined by the system administrator. In addition, each Gateway-ST configured will require additional disk space (at least 40 blocks (20 KB)) for configuration scripts. Communications Hardware Requirements DEC MicroServer DECnet SNA Gateway-ST software runs on the DEC MicroServer unit, which is supported in the following forms: o DEMSA-AA for use with 120V AC power supplies o DEMSA-AB for use with 240V AC power supplies The DEC MicroServer has a built-in LAN controller but needs a suit- able connection to connect to the customer's LAN, together with any necessary extension cables. The DEC MicroServer uses adapter cables to provide the necessary in- terchange circuits at the appropriate electrical interface types and ISO standard connections for each synchronous line. One of these ca- bles is needed for each line used. Table 2 shows the cable numbers for each of the electrical interface types. 9 Table 2: Adapter Cables ___________________________________________________________________ Electrical Adapter Connector/ Interface Cable Pinout ___________________________________________________________________ RS232-D/V.24 BS19D-02 ISO 2110 V.35 BC19F-02 ISO 2593 ___________________________________________________________________ The BS19D-02 cable provides the RS232-D/V.24 interface, but is sup- plied with an adapter that allows it to be used for RS232-C as well. DEC MicroServer synchronous ports do not provide clock signals; an ex- ternal clock source (such as a modem or modem eliminator) is required. DEC MicroServer-SP DECnet SNA Gateway-ST software runs on the DEC MicroServer-SP unit, which is supported in the following forms: o DEMSB-AA for use with 120V AC power supplies o DEMSB-AB for use with 240V AC power supplies The DEC MicroServer-SP has a built-in LAN controller but needs a suit- able connection to connect to the customer's LAN, together with any necessary extension cables. The DEC MicroServer uses adapter cables to provide the necessary in- terchange circuits at the appropriate electrical interface types and ISO standard connections for each synchronous line. Table 3 shows the cable numbers for the electrical interface types supported. 10 Table_3:_Adapter_Cables ___________________________________________________________________ Electrical Adapter Connector/ Interface Cable Pinout ___________________________________________________________________ RS232-D/V.24 BS19D-02 ISO 2110 ___________________________________________________________________ The BS19D-02 cable provides the RS232-D/V.24 interface, but is sup- plied with an adapter that allows it to be used for RS232-C as well. The DEC MicroServer-SP synchronous port does not provide clock sig- nals; an external clock source (such as a modem or modem eliminator) is required. Other Hardware Required o VT series terminal for diagnostic use o IBM hardware support The DEC ChannelServer hardware has been tested and warranted with the following IBM and PCM hardware configurations: IBM 9370 Models 40 to 90 IBM 4381 All models IBM 3081 D,G,K IBM 3083 B,E,J,C IBM 3084 ES/3090[TM] All models ES/9000[R] All models Amdahl[R] 5860 Amdahl 5870 Amdahl 5990-700 Amdahl 5990-1400 NAS AS/XL-V60 NAS 8083 11 NAS 6650 IBM 3044 Channel-Extender Model 1* IBM ESCON[R] Converter 9034 connected to ESCON compatible ES/9000 or ES/3090* * Supported only with IBM mainframes. OPTIONAL HARDWARE Optional hardware consists of additional adapter cables (with the nec- essary extension cables and modems) to make use of additional synchronous lines on the DEC MicroServer, up to the maximum defined in the SPD. SOFTWARE REQUIREMENTS OpenVMS Alpha Environment o OpenVMS Alpha Operating System V6.2 or higher (SPD 25.01.xx) o DECnet-Plus V7.1 for OpenVMS Alpha (SPD 50.45.xx) OpenVMS VAX Environment o OpenVMS VAX Operating System V6.2 or higher (SPD 25.01.xx) o DECnet-Plus V7.1 for OpenVMS VAX (SPD 25.03.xx) or DECnet/OSI V6.3 for OpenVMS See the Optional Software section of this Software Product Descrip- tion for availability and required versions of optional software. 12 SOFTWARE LICENSING Users need a separate license for each DEC MicroServer unit on which they will be using DECnet SNA Gateway-ST (except as otherwise spec- ified by DIGITAL). The DECnet SNA Gateway for Synchronous Transport license applies to the DEC MicroServer unit on which the software executes. This software is furnished only under a license. For more information about DIGITAL's licensing terms and policies, contact your local DIG- ITAL office. License Management Facility Nonsupport This product does not provide support for the OpenVMS License Manage- ment Facility. A Product Authorization Key (PAK) is not required for installation or use of this version of the product. CLUSTER ENVIRONMENT This layered product is fully supported when installed on any valid and licensed VMScluster[TM]* configuration without restrictions. The Hardware Requirements section of this product's Software Product De- scription explains any special hardware required by this product. * VMScluster configurations are fully described in the OpenVMS Clus- ter Software Product Description (29.78.xx) and include CI[TM], Eth- ernet, and Mixed Interconnect configurations. OpenVMS TAILORING CLASSES The following OpenVMS classes are required for full functionality of this layered product: o OpenVMS Required Saveset o Network Support 13 For more information on OpenVMS classes and tailoring, refer to the OpenVMS Operating System for Alpha and VAX Software Product Descrip- tion (SPD 25.01.xx). OPTIONAL SOFTWARE Table 4 lists the optional DECnet SNA access routines available for use with DECnet SNA Gateway-ST. For information on these products, con- sult the respective Software Product Descriptions. Table_4:_Access_Routines ___________________________________________________________________ Supported on OpenVMS Alpha Systems ___________________________________________________________________ Digital SNA 3270 Terminal Emulator for OpenVMS (SPD 26.84.xx) Digital SNA APPC/LU6.2 Programming Interface for OpenVMS (SPD 26.88.xx) Digital SNA Data Transfer Facility for OpenVMS (SPD 27.85.xx) DECnet SNA Application Programming Interface for OpenVMS (SPD 26.86.xx) DECwindows[TM] DECnet SNA 3270 Terminal Emulator for OpenVMS (SPD 31.58.xx) Digital SNA 3270 Data Stream Programming Interface for OpenVMS (SPD 26.87.xx) Digital SNA Printer Emulator for OpenVMS (SPD 26.70.xx) Digital SNA Remote Job Entry for OpenVMS (SPD 26.85.xx) 14 ___________________________________________________________________ Supported on OpenVMS VAX Systems ___________________________________________________________________ Digital SNA 3270 Terminal Emulator for OpenVMS (SPD 26.84.xx) Digital SNA APPC/LU6.2 Programming Interface for OpenVMS (SPD 26.88.xx) Digital SNA Data Transfer Facility for OpenVMS (SPD 27.85.xx) DECnet SNA Application Programming Interface for OpenVMS (SPD 26.86.xx) DECwindows DECnet SNA 3270 Terminal Emulator for OpenVMS (SPD 31.58.xx) Digital SNA 3270 Data Stream Programming Interface for OpenVMS (SPD 26.87.xx) Digital SNA Printer Emulator for OpenVMS (SPD 26.70.xx) Digital SNA Remote Job Entry for OpenVMS (SPD 26.85.xx) DECmessageQ[TM] for OpenVMS (SPD 46.25.xx) VAX Message Router/P Gateway (SPD 28.94.xx) VAX Message Router/S Gateway (SPD 29.24.xx) ___________________________________________________________________ Supported on MS[R]-Windows[TM] Systems ___________________________________________________________________ RUMBA[R] for Digital, Mainframe Edition (formerly RUMBA for PATHWORKS[TM]) (SPD 44.95.xx) ___________________________________________________________________ IBM SUPPORTED CONFIGURATIONS The DECnet SNA Gateway-ST software is warranted with the IBM software configurations listed in Table 5. 15 Table 5: IBM Software Configurations ___________________________________________________________________ Software Product Version Release ___________________________________________________________________ MVS/SP[TM] (MVS/XA[TM]) 2 2.3 MVS/ESA[TM] SP 4 2.0, 3.0 VM/XA SP 1 2.1 VM/ESA[R] 2 2.0 VSE/SP 3 2.0 ACF/VTAM[TM] 4 2.0, 3.0, 4.0 ACF/NCP/VS (for the 3745) 6 3.0 7 3.0, 4.0, 5.0, 6.0 NetView[R] 2 3.0, 3.1 OS/390[R] 1 2.0, 3.0 2 4.0 ___________________________________________________________________ FUJITSU SUPPORT The Fujitsu hardware and software environments listed below are sup- ported with the following restrictions: These configurations are supported by DIGITAL Japan for installations in the Country of Japan only and only with the "F" version access rou- tines listed below, which are available from and supported by DIGI- TAL Japan. Please contact DIGITAL Japan for additional information. Hardware o FUJITSU FACOM M-series mainframe o FUJITSU F2806G front end 16 Software o FUJITSU NCP-G V10L20 (similar to IBM's ACF/NCP) o FUJITSU OS IV/F4 MSP E20 (similar to IBM's MVS/XA[TM]) o FUJITSU VTAM-G V10L20 (similar to IBM's VTAM) "F" Access Routines The following products provide local language support and are supported by DIGITAL Japan for use with Fujitsu environments in Japan. ___________________________________________________________________ F Access Routines Version SPD (Japan) ___________________________________________________________________ F6650 Terminal 1.0 27.J3.xx Emulator F6650 Data Stream 1.0 27.J4.xx Programming Interface DECwindows F6650 1.0 27.T7.xx Terminal Emulator for VMS F-RJE 1.0 27.J5.xx F-PRE 1.0 26.T8.xx ___________________________________________________________________ GROWTH CONSIDERATIONS The minimum hardware and software requirements for any future version of this product may be different from the requirements for the cur- rent version. 17 DISTRIBUTION MEDIA For Alpha Systems This product is available as part of the OpenVMS Alpha Software Product Library on CD-ROM. The software documentation for this product is available as part of the OpenVMS Alpha Online Documentation Library on CD-ROM. Documen- tation in hardcopy format can be ordered separately. For VAX Systems 9-track 1600 BPI Magtape This product is also available as part of the OpenVMS VAX Software Product Library on CD-ROM. The software documentation for this product is also available as part of the OpenVMS VAX Online Documentation Library on CD-ROM. Documentation in hardcopy format can be ordered separately. YEAR 2000 READY The product was installed on a test machine and the system date was set so that the rollover to 1-JAN-2000 and date handling in the twenty- first century were observed to work correctly. SOFTWARE WARRANTY This software is provided by DIGITAL with a 90-day warranty in accordance with the DIGITAL warranty terms applicable to the license purchase. 18 Warranty Limitations IBM Supported Configurations This product has been designed to operate with the IBM host systems and software subsystems listed in the Other Hardware Required and IBM Supported Configurations sections of this Software Product Description. While this software may function correctly with other IBM software and equipment, and with hardware and software other than that supported by IBM, DIGITAL cannot offer its standard warranty for this product unless it has been tested with such equipment and software configurations and found acceptable to DIGITAL. For a complete list of IBM application subsystems that the various DECnet SNA access routines have been certified against and that are supported configurations by DIGITAL, please consult the respective access routine Software Product Descriptions. (See Table 4 in the Optional Software section of this product's Software Product Description.) ORDERING INFORMATION [Note: The license, media, and documentation for this product are the same on both the OpenVMS Alpha and OpenVMS VAX platforms.] Software License: QL-S01A9-AA Software Media: QA-S01AA-** Media and documentation for this product are also available on the OpenVMS Alpha and OpenVMS VAX Software Product Libraries and Online Documentation Libraries on CD-ROM. Documentation in hardcopy format can be ordered separately. Software Documentation: QA-S01AA-GZ Software Product Services: QT-S01A*-** QSF01-SZ (Orientation/Installation) o Denotes variant fields. For additional information on available licenses, services, and media, refer to the appropriate price book. The above information is valid at time of release. Please contact your local DIGITAL office for the most up-to-date information. 19 SOFTWARE PRODUCT SERVICES A variety of service options are available from DIGITAL. For more information, contact your local DIGITAL office. [R] Amdahl is a registered trademark of Amdahl Corporation. [R] AT&T and Data Phone are registered trademarks of American Telephone & Telegraph Company. [R] IBM, ES/9000, ESCON, NetView, OS/390, and VM/ESA are registered trademarks of International Business Machines Corporation. [R] MS and Windows are registered trademarks of Microsoft Corporation. [R] RUMBA is a registered trademark of Wall Data, Inc. [TM] Bell is a trademark of Bell Telephone Companies. [TM] ES/3090, MVS/ESA, MVS/SP, MVS/XA, and VTAM are trademarks of International Business Machines Corporation. [TM] CI, DEC, DECmessageQ, DECnet, DECstation, DECsystem, DECwindows, DIGITAL, MicroVAX, MicroVAX I, OpenVMS, PATHWORKS, TK, VAX, VAX-11/725, VAXcluster, VAXserver, VAXstation, VMS, VMScluster, VT, and the DIGITAL logo are trademarks of Digital Equipment Corporation. All other trademarks and registered trademarks are the property of their respective holders. © 1998 Digital Equipment Corporation. All rights reserved. 20