Introduction _____________________________ 1.5.2 OpenVMS Ambassadors? The OpenVMS Ambassadors are senior HP engineers with advanced technical knowledge and advanced training in OpenVMS, with detailed knowledge of current and future OpenVMS releases and product plans, and with contacts directly with the HP and ISV hardware and software engineering organizations developing OpenVMS and OpenVMS hardware platforms, as well as layered products and tools. Further, Ambassadors are experienced with integrating HP OpenVMS and application-specific products and ISV applications to solve specific business requirements. OpenVMS Ambassadors are based throughout the world. Your HP sales representative or HP reseller will be able connect you with your local OpenVMS Ambassador. _____________________________ 1.5.3 Contact for OpenVMS Marketing Issues and Questions? Please see Section 3.5. _____________________________ 1.5.4 Contact URLs for OpenVMS Technical Issues? For technical issues and technical support, please contact your software support organization, or your local HP Customer Support Center or HP Reseller. In North America, you can call 1-800-OK-COMPAQ. Please remember to review and to bookmark the following support URLs: o http://www.openvms.compaq.com/support/ o http://askq.compaq.com/ o http://www.hp.com/go/openvms/wizard/ o ftp://ftp.support.compaq.com/public/vms/vax/... o ftp://ftp.support.compaq.com/public/vms/axp/... 1-10 _______________________________________________________ 2 General Information __________________________________________________________ 2.1 What is OpenVMS? What is its history? OpenVMS, originally called VMS (Virtual Memory System), was first conceived in 1976 as a new operating system for the then-new, 32-bit, virtual memory line of computers, eventually named VAX (Virtual Address eXtension). The first VAX model, the 11/780, was code-named "Star", hence the code name for the VMS operating system, "Starlet", a name that remains to this day the name for the system library files (STARLET.OLB, etc.). VMS version X0.5 was the first released to customers, in support of the hardware beta test of the VAX-11/780, in 1977. VAX/VMS Version V1.0 shipped in 1978, along with the first revenue-ship 11/780s. OpenVMS was designed entirely within HP and specifically within the former Digital Equipment Corporation (DIGITAL). Two of the principal designers were Dave Cutler and Dick Hustvedt, though with a wide variety of other contributors. OpenVMS was conceived as a 32-bit, virtual memory successor to the RSX- 11M operating system for the PDP-11. Many of the original designers and programmers of OpenVMS had worked previously on RSX-11M, and many concepts from RSX-11M were carried over to OpenVMS. OpenVMS VAX is a 32-bit, multitasking, multiprocessing virtual memory operating system. Current implementations run on VAX systems from HP and other vendors. OpenVMS Alpha is a 64-bit multitasking, multiprocessing virtual memory operating system. Current implementations run on Alpha systems from HP, and other vendors. 2-1 General Information Work to port OpenVMS to systems based on the Intel IA-64 architecture and specifically to the Itanium Processor Family is presently underway. For more details on OpenVMS and its features, please read the OpenVMS Software Product Description at: o http://www.compaq.com/info/spd/ OpenVMS typically uses SPD 25.01.xx and/or SPD 41.87.xx. Additional information on the general features of various OpenVMS releases, release dates, as well as the development project code names of specific releases, is available at: o http://www.openvms.compaq.com/openvms/os/openvms- release-history.html Additional historical information-as well as pictures and a variety of other trivia-is available in the VAX 20th anniversary book: o http://www.openvms.compaq.com/openvms/20th/vmsbook.pdf For information on the FreeVMS project, and on hobbyist and educational versions of OpenVMS, please see: o http://www.free-vms.org/ o http://www.openvmshobbyist.org/ o http://www.openvmsedu.com/ Also please see the related software licensing topics Section 2.7.4, Section 2.7.1, and Section 2.14. __________________________________________________________ 2.2 What is the difference between VMS and OpenVMS? VMS and OpenVMS are two names for the same operating system. Originally, the operating system was called VAX-11/VMS; it changed to VAX/VMS at around VAX/VMS V2.0. When the VMS operating system was ported to the Alpha platform, it was renamed OpenVMS, for both VAX and Alpha (and for the Itanium Processor Family), in part to signify the high degree of support for industry 2-2 General Information standards such as POSIX, which provides many features of UNIX systems. For those versions with POSIX, an OpenVMS license allows you to install and run POSIX for OpenVMS at no additional charge; all you need is the media and documentation which can be found on the Consolidated Distribution and On-Line Documentation CD-ROMs. Support for the POSIX package on more recent OpenVMS releases is not available, various parts of POSIX such as calls from the API are being integrated more directly into OpenVMS. For more information on POSIX for VMS see question SOFT2 What became confusing is that the OpenVMS name was introduced first for OpenVMS AXP V1.0 causing the widespread misimpression that OpenVMS was for Alpha AXP only, while "regular VMS" was for VAX. In fact, the official name of the VAX operating system was changed as of V5.5, though the name did not start to be actually used in the product until V6.0. The proper names for OpenVMS on the two platforms are now "OpenVMS VAX" and "OpenVMS Alpha", the latter having superseded "OpenVMS AXP". _____________________________ 2.2.1 How do I port from VMS to OpenVMS? You already did. Wasn't that easy? Please see Section 2.2 for details. __________________________________________________________ 2.3 Which is better, OpenVMS or UNIX? This question comes up periodically, usually asked by new subscribers amd new posters who are long-time UNIX or Linux users. Sometimes, the question is ignored totally; other times, it leads to a long series of repetitive messages that convince no one and usually carry little if any new information. Please do everyone a favor and avoid re-starting this perpetual, fruitless debate. 2-3 General Information That said, OpenVMS and the better implementations of UNIX are all fine operating systems, each with its strengths and weaknesses. If you're in a position where you need to choose, select the one that best fits your own requirements, considering, for example, whether or not the layered products or specific OS features you want are available, and considering the expected cost-of-ownership over the lifetime of the system installation. __________________________________________________________ 2.4 Is HP continuing funding and support for OpenVMS? Yes. Active development of new OpenVMS releases is underway, as well as the continuation of support. Please see the following URLs for details, roadmaps, and related information: o http://www.openvms.compaq.com/ o http://www.openvms.compaq.com/OPENVMS/strategy.html o http://www.openvms.compaq.com/openvms/roadmap/openvms_ roadmaps.htm o http://www.openvms.compaq.com/openvmstimes/ o http://www.compaq.com/inform/ __________________________________________________________ 2.5 What OpenVMS CD-ROM distribution kits are available? Various distributions are available. For information on the available part numbers and current products (OpenVMS distribution kits, media, documentation, etc) and associated licensing information, please see the OpenVMS Software Product Description (SPD), available at: o http://www.compaq.com/info/spd/ OpenVMS typically uses SPD 25.01.xx and/or SPD 41.87.xx. 2-4 General Information The CD-ROMs listed in Table 2-1 contain just the OpenVMS Alpha operating system. These are bootable, and can be used to run BACKUP from CD-ROM. ________________________________________________________________ Table 2-1 OpenVMS Media Kits _______________________________________________________ Part______________Description__________________________ QA-MT1AP-H8 OpenVMS Alpha V6.1-1H2 hardware release CD-ROM QA-MT1AG-H8 OpenVMS Alpha V6.2-1H3 hardware release CD-ROM QA-MT1AD-H8 OpenVMS Alpha V7.1-1H1 hardware release CD-ROM QA-MT1AR-H8 OpenVMS Alpha V7.1-2 maintenance release CD-ROM QA-MT1AT-H8 OpenVMS Alpha V7.2-1 maintenance release CD-ROM QA-MT1AU-H8 OpenVMS Alpha V7.2-1H1 hardware ___________________________release_CD-ROM_______________________ The table Table 2-2 contains the consolidated ECO distribution kit subscriptions, and these provide sites with eight updates of the current ECO kits per year: ________________________________________________________________ Table 2-2 OpenVMS ECO Kits _______________________________________________________ Part______________Description__________________________ QT-3CQAA-C8 OpenVMS Alpha _________QT-3CRAA-C8_______OpenVMS_VAX__________________________ The OpenVMS VAX and OpenVMS Alpha source listings CD-ROM sets listed in Table 2-3 include the source listings of most of OpenVMS, and these CD-ROM sets are invaluable for any folks working directly with OpenVMS internals, as well as folks interested in seeing examples of various programming interfaces. 2-5 General Information ________________________________________________________________ Table 2-3 OpenVMS Source Listings CD-ROM Kits _______________________________________________________ Part______________Description__________________________ QB-MT1AB-E8 OpenVMS Alpha Source Listings CD-ROM QT-MT1AB-Q8 OpenVMS Alpha Source Listings CD-ROM Updates QB-001AB-E8 OpenVMS VAX Source Listings CD-ROM QT-001AB-Q8 OpenVMS VAX Source Listings CD-ROM ___________________________Updates______________________________ __________________________________________________________ 2.6 In what language is OpenVMS written? OpenVMS is written in a wide variety of languages. In no particular order, OpenVMS components are implemented using Bliss, Macro, Ada, PLI, VAX and DEC C, Fortran, UIL, VAX and Alpha SDL, Pascal, MDL, DEC C++, DCL, Message, and Document. And this is certainly not a complete list. However, the rumor is NOT true that an attempt was made to write pieces of OpenVMS in every supported language so that the Run-Time Libraries could not be unbundled. (APL, BASIC, COBOL and RPG are just some of the languages NOT represented!) There are a large variety of small and not-so-small tools and DCL command procedures that are used as part of the OpenVMS build, and a source code control system capable of maintaining over a hundred thousand source files across multiple parallel development projects, and overlapping releases. __________________________________________________________ 2.7 Obtaining and Transfering OpenVMS licensees? The following sections describe hobbyist and educational license programs, as well as information on commercial licenses and transfers. For information on the available commercial OpenVMS licenses and for information on license transfers, please see Section 2.7.4. For information on the licensing implementation, troubleshooting licensing 2-6 General Information problems, on the License Unit Requirements Table (LURT), and other related details, please see Section 5.38. _____________________________ 2.7.1 Questions asked by Hobbyist OpenVMS licensees? If you are a member of an HP-recognized user group (eg: Encompass, Enterex, DECUS), and are considering acquiring and using a VAX or Alpha system for hobbyist (non-commercial) use, (free) license product authorization keys (PAKs) for OpenVMS VAX, OpenVMS Alpha, and layered products are available. In addition to the license keys, OpenVMS VAX and Alpha distribution CD-ROM distribution kits are available with OpenVMS, DECwindows Motif, DECnet and TCP/IP networking, compilers, and a variety of layered products. (While the hobbyist CD-ROM distributions are intended for and tailored for OpenVMS Hobbyists, the contents and capabilities of the Hobbyist installation kits included within the OpenVMS Hobbyist distribution do not differ from the standard distribution installation kits. The products are chosen to reflect the most popular products and the space available on the media.) If you have questions on what else is authorized by the license agreement and on what other distribution media is available to you, well, please read the applicable software license agreement(s). For further information, please link to: o http://www.openvmshobbyist.org/ On the OpenVMS Hobbyist license registration form at the above website (as of June 2003), you are offered the choice of the "OpenVMS VAX" license(s), the "OpenVMS Alpha" license(s), and the "Layered Products" licenses. You will want the operating system license for your particular OpenVMS platform and you will want the "Layered Products" licenses. You will want to select and to acquire two sets of license PAKs. 2-7 General Information For vendors wishing to license products specifically for hobbyist use (and to not issue hobbyist PAKs), the program provides hobbyists with the license PAK OPENVMS-HOBBYIST. If you plan to use a hardware emulator (eg: VAX emulator) on a Microsoft Windows platform, make sure you have an OpenVMS distribution kit that can be installed and/or booted with the particular emulator package you plan to use. For additional information on emulators, please see Section 13.13 and particularly please see the emulator-related documentation. _____________________________ 2.7.2 OpenVMS Educational and CSLG licenses? For information on OpenVMS licenses for educational customers, please see the HP Campus Software License Grant (CSLG) license program and the OpenVMS Educational license program: o http://www.openvmsedu.com/ _____________________________ 2.7.3 What developer and partner licensing programs are available? Commercial software developers can join the HP DSPP program, and can (potentially) receive discounts on various software product licenses and software distributions, as well as on hardware purchases. The DSPP program is the descendent of the DIGITAL ISVN and DIGITAL ASAP programs and the Compaq CSA program, and the analogous developer and partner programs at HP. Please see Section 2.14 for additional details on the DSPP program. For information on the OpenbVMS Hobbyist and OpenVMS Educational license programs, please see Section 2.7.1. 2-8 General Information _____________________________ 2.7.4 How do I obtain or transfer an OpenVMS license? To transfer a commercial OpenVMS license from one owner to another, or to purchase a commercial license, you can contact HP at 1-800-OK-COMPAQ (in North America), or your local or regional sales office or reseller. __________________________________________________________ 2.8 Does OpenVMS support the Euro currency symbol? OpenVMS can generate the %xA4 character code used for the Euro, and the DECwindows DECterm can display the glyph. Please check with the vendor of your terminal or terminal emulator for additional details. For additional information on the support of the European Monetary Union Euro currency glyph on OpenVMS, please see: o http://www.openvms.compaq.com/euro/ __________________________________________________________ 2.9 OpenVMS Ports? Itanium? Ports to Intel (IA-32) systems? OpenVMS has been ported to and is operational on three architectures: VAX, Alpha, and IA-64. VAX is the oldest, and limited to 32-bit virtual and up to 34- bit physical addressing. Alpha and IA-64 architectures are both 64-bit architectures, with 64-bit virtual addressing available. The most common commodity platform available in the industry is clearly the Intel IA-32 series, with 32-bit addressing. Technically, OpenVMS and specifically the OpenVMS VAX 32-bit environment is already available on IA-32 systems. For information on how this is possible, please see one of the available VAX emulator products referenced over in Section 13.13. As for (the lack of) a native port for IA-32, OpenVMS Engineering presently and continues to believe that there would be insufficient market (read: profit, customer interest) to justify the cost involved in a native port of OpenVMS to systems using the Intel IA-32 architecture. In addition to the direct costs involved in any port and in addition to the substantial effort involved in moving backwards from a 64-bit 2-9 General Information environment on Alpha and on IA-64 to a 32-bit platform (such as IA-32), and the exceedingly non-trivial device qualification costs and the costs in moving backwards into older PCI and I/O environments (IA-32 systems more than a few years old have equivalently aged I/O support and buses), each organization and each person maintaining a product or a package for OpenVMS will have to justify a port to "OpenVMS Pentium" or "OpenVMS Athalon", akin to the decisions and effort involved in porting a product from OpenVMS VAX to OpenVMS Alpha, or to OpenVMS I64. Platform ports of many of the various products can be easy. Other products can depend on platform- specific features, and the associated ports can be more involved. Ports of operating systems are very large and involved projects. The prerequisite product requirements for a port are also non-trivial, as well- compilers in particular are obviously required, and the suite of compilers provided must maintain a very high degree of source-level compatibility across the platforms. In the case of the HP Integrity port, OpenVMS I64 V8.0 used cross-compilers and cross- tools operating on OpenVMS Alpha systems, while V8.1 is expected to have native compilers available. The OpenVMS I64 port was centrally built using the existing OpenVMS Alpha environment and around the work and the knowledge from the OpenVMS Alpha port, and OpenVMS Engineering fully expects that customers and ISVs will use and will continue to use OpenVMS Alpha systems to assist with their own ports to OpenVMS I64. OpenVMS Engineering is well aware of the AMD Opteron AMD64 (64-bit) platform, and of terms such as Hammer and Sledgehammer. (At least one of the VAX emulators can reportedly utilize the Opteron instruction set, please contact the VAX emulator vendor(s) or maintainer(s) for assistance and details on their products.) OpenVMS Engineering has also heard many of the various "Yamhill" rumors as well. There are no plans to provide a native port of HP OpenVMS for any systems based on AMD Opteron. 2-10 General Information As part of the work leading to the Itanium port, senior engineers had extensively evaluated the products and the architectures available across the high-end 64- bit computing space, and chosen to target Itanium for 64-bit environments-this while under the Compaq organization. This included looking at IA-32. HP (a co- developer of Itanium with Intel) had seperately chosen to target Intel Itanium for its high-end computer products. Compaq then announced plans for the future of Alpha through EV79 products and platforms, and HP (entirely seperately) announced plans for PA-RISC products and platforms. The Itanium target has been maintained consistently since the Itanium port was announced by Compaq, and has also been consistently maintained by HP and by the combined company. For those folks prefering to follow the schedules and the product deliveries, OpenVMS Engineering had OpenVMS I64 V8.0 ready (internally) ahead of schedule-and with more features available within the release than had been originally planned for the release. (For information on and for schedules of future OpenVMS releases, please see the roadmap that is available at the OpenVMS website.) OpenVMS I64 itself does not require and does not plan to utilize the Itanium IA-32 32-bit environment for the operation of OpenVMS itself. OpenVMS I64 V8.0 runs natively on the Itanium processor family, with no use of IA-32 instructions; this starting with the initial release of OpenVMS I64 V8.0, and the fully-native operations of OpenVMS are expected to continue through future releases. While OpenVMS can and does support 32-bit applications and addressing on Itanium, this is done with sign-extension addressing techniques entirely analogous to what was done with 32-bit applications operating in the 64-bit Alpha environment. But yes, a native IA-32 port or a native AMD Opteron port of OpenVMS would certainly be nice to have-this, of course, following the traditional Linux preference for having a Linux port available for most (all?) computer architectures known, and even for certain high-end refrigerators and toasters and similar appliances and appliance-like devices. (The downside 2-11 General Information of this all-encompassing approach: this requires near-infinite engineering and support costs from the various vendors involved, and the qualification efforts and costs of most everything-everywhere. Or reduced or eliminated testing and support efforts. Or an unfortunate combination of these two. These costs are huge, and the benefits derived from the work are comparatively small when given the comparable costs of more targeted (and thus supported and supportable) hardware configurations- the platform targets are and must be carefully selected and considered by each vendor. Put another way, there are no plans to provide a native port of HP OpenVMS for systems based on Intel IA-32 processors, nor for systems based on AMD Opteron processors. (There are even still a few computer systems and platforms that lack Linux ports, after all.) All this material having been written, have you looked at the system configurations and pricing of the available HP Integrity Intel Itanium systems? Low- end computer hardware is clearly a commodity product, and the systems are priced, serviced, upgraded, and replaced accordingly. Intel Itanium is a commodity microprocessor presently used in platforms available from various hardware vendors, including (obviously) from HP. Further, Itanium is a microprocessor available from and supported by Intel, a semiconductor vendor known for exceedingly high-volume microprocessor fabrication process and production capabilities. For information on supported platforms and processors, please see the OpenVMS Software Product Description (SPD) at: o http://www.compaq.com/info/spd/ OpenVMS typically uses SPD 25.01.xx and/or SPD 41.87.xx. Please see Section 14.4.5 for Intel Itanium terminology. 2-12 General Information __________________________________________________________ 2.10 Are there any network-accessible OpenVMS systems? Yes, though various restrictions can and do apply. o Hobbes Hobbes is a MicroVAX 3100 Model 40 for which free access and accounts are available to OpenVMS enthusiasts. This system has BASIC, Pascal, Fortran, and C compilers installed. If you would like an account on Hobbes, please see the FAQ at http://www.hobbesthevax.com/. o OpenVMS Galaxy Test-Drive HP currently offers an OpenVMS Galaxy Test-Drive system, based on an AlphaServer 4100 series configured as two instances of the OpenVMS operating system. For details, please visit: o http://www.testdrive.hp.com/ o HP DSPP Test-Drive HP DSPP program offers various test-drive systems, including an HP Integrity Itanium development system and an HP OpenVMS I64 installation on an HP Integrity rx2600 server. For details on the DSPP program and on the test-drive systems, please see section Section 2.7.3 and please visit: o http://www.testdrive.hp.com/ o http://www.hp.com/dspp/ The test-drive systems do require registration, though access to the systems is free. o Encompasserve telnet://eisner.decus.org/ o OpenECS OpenECS offers free access to a VAX 6000 model 530 system. If interested, please visit: http://vax6k.openecs.org/ 2-13 General Information __________________________________________________________ 2.11 What version of OpenVMS do I need? For information on supported platforms, please see the OpenVMS Software Product Description (SPD) for the particular OpenVMS version of interest. o http://www.compaq.com/info/spd/ OpenVMS typically uses SPD 25.01.xx and/or SPD 41.87.xx. For a table of OpenVMS versions for various platforms, please see: o http://www.openvms.compaq.com/openvms/supportchart.html For information on the Multia, related Alpha single-board computers, or other officially unsupported systems, please see Section 14.4.1 and Section 14.4.2.1. The following is a rule-of-thumb for Alpha platform support. The table Table 2-4 contains the earliest OpenVMS Alpha release with support for a particular series of Alpha microprocessors: ________________________________________________________________ Table 2-4 OpenVMS Alpha Version Rule-Of-Thumb _______________________________________________________ Microprocessor General Generation____________OpenVMS_Version_______Comments___ 21064 EV4 V1.0 few systems; most EV4 require later; upgrade available 21164 EV5 V6.2 subsequent upgrade available 2-14 General Information ________________________________________________________________ Table 2-4 (Cont.) OpenVMS Alpha Version Rule-Of-Thumb _______________________________________________________ Microprocessor General Generation____________OpenVMS_Version_______Comments___ 21164A EV56 V6.2-1H3 subsequent upgrade to V7.1 and later 21264 EV6 V7.1-2 subsequent upgrade typically to V7.2-1 or later 21264A EV67 V7.1-2 subsequent upgrade typically to V7.2-1 or later xxxxxx EV68 V7.2-1 believed/probable; currently _____________________________________________________expectation __________________________________________________________ 2.12 How can I submit OpenVMS Freeware? For the guidelines and submission info, please visit the URL: o http://www.hp.com/go/openvms/freeware/ To order the current OpenVMS Freeware CD-ROM kit (shipping and handling charges apply), please request part number QA-6KZAA-H8. __________________________________________________________ 2.13 Porting applications to OpenVMS? Porting can range from simple to rather complex, and depends on the features used on the original platform. 2-15 General Information This section covers generic porting, and porting from OpenVMS VAX to OpenVMS Alpha. (Porting from OpenVMS VAX to OpenVMS Alpha is often quite simple and involves little more than rebuilding from source, though a few applications using features specific to VAX will require some additional effort to port.) Several manuals on porting from OpenVMS VAX to OpenVMS Alpha are available in the OpenVMS documentation set, including information on porting VAX Macro32 assembler code to the Macro32 compiler on OpenVMS Alpha, on management differences, on upgrading privileged code, and application migration: o http://www.openvms.compaq.com/doc/ o http://www.openvms.compaq.com/commercial/ Details on the C programming environment are available at: o http://www.openvms.compaq.com/commercial/c/c_ index.html Details on porting VAX C to HP C are are available at: o http://www.openvms.compaq.com/commercial/c/index_ vax.htm An OpenVMS Porting Library is available at: o http://www.openvms.compaq.com/ebusiness/Technology.html Information on the Enterprise Toolkit, a Visual-based development environment for developing applications for OpenVMS using a Microsoft platform, is available at: o http://www.openvms.compaq.com/commercial/et/et_ index.html Details on DCE, CORBA, BridgeWorks, and COM/DCOM middleware is available at: o http://www.openvms.compaq.com/commercial/middleware.html 2-16 General Information Information on the COE standards is available at: o http://diicoe.disa.mil/coe/ A wide variety of programming development tools and middleware are available as commercial products (eg: DECset, IBM WebSphere MQ-formerly MQseries), and various tools are also available as shareware or as Freeware. Please see other sections of this FAQ, and please see: o http://www.compaq.com/csa/directory/ __________________________________________________________ 2.14 What resources are available to OpenVMS software developers? The HP Developer and Software Product Partner (DSPP) program is open to and intended to support and to assist HP OpenVMS software partners, consultants, and service providers: o http://www.hp.com/dspp/ DSPP provides members with various benefits, please see the website for details. For those not familiar with the DSPP program or with its history, the DIGITAL Association of Software and Application Partners (ASAP) program and the DIGITAL Independent Software Vendors Network (ISVN) program were incorporated into the Compaq CSA program, and the CSA program has subsequently been incorporated into the HP DSPP program. Please see Section 2.7.3 for additional details on the DSPP program. __________________________________________________________ 2.15 memory management, resource management, process scheduling, etc? So you have been instructed to write a school research paper on OpenVMS, and you need technical content on the OpenVMS Virtual Memory System, on any memory segmentation, on OpenVMS Resource Management, on the 2-17 General Information OpenVMS File System, on the OpenVMS user interface, etc. Invariably, your professor/instructor/teacher will ask you a series of questions. Most commonly, the questions will request descriptions of one or more of the following items, and at varying levels of detail: o process scheduling algorithm(s) o Interprocess comunications o Process or system synchronization constructs o Memory management and/or virtual memory implementation o RMS or XQP file structures o Resource management o History of HP OpenVMS o History of Compaq and/or of Digital Equipment Corporation (DEC) Any particular presentation or research paper, and particularly a scholastic presentation, can have many different potential target audiences, and very different presentation levels. Further, the usual underlying reason for scholastic presentations and scholastic research projects really has little to do with the subject matter, it is a task specifically intended to teach the student(s) (eg: you) how to perform the research. The instructor already knows most of (all of?) the information that you have been asked to collect. For very technical details on OpenVMS and OpenVMS internals, the book you want is the Internals and Data Structures Manual (IDSM), available in your school or computing center library, and the IDSM can also be purchased. Additional technical details of the Alpha microprocessor are available in the Alpha Architecture Reference Manual documentation that is available for download. (Pointers to Alpha technical documentation are available in Section 14.6, and elsewhere.) 2-18 General Information For higher-level (less technical) details, the OpenVMS documentation set is available on-line. The Programming Concepts and the File Systems manual are probably the best manuals to start with, depending on the particular level of detail the research requires. And please understand the hesitation of various folks to provide you with a completely-written research report on your topic. Why? We might have to work with you after you graduate-you need to know how to perform at least basic research on your own, regardless of the topic. __________________________________________________________ 2.16 Basic Units of Measurement? OpenVMS and the underlying hardware use various units of measurement for disk and memory storage, and related abbreviations also typically exist. This section covers the most common units, and the associated abbreviations. _____________________________ 2.16.1 How many bytes are in a disk block? A disk block is the minimum unit of disk storage allocation in OpenVMS. Under OpenVMS VAX and OpenVMS Alpha, the disk volume block size is consistent, with each block containing 512 bytes. The minimum disk allocation granularity actually permissible (in the ODS-2 and ODS-5 volume structures commonly used on OpenVMS) is determined on a per-volume basis, and is typically based on a combination of the total number blocks on the disk volume and the total size of the volume storage bitmap. The allocation granularity is known as the volume cluster factor- the cluster factor is the number of blocks in a disk cluster, and it is the smallest number of blocks that can be allocated on a particular disk volume. 2-19 General Information Prior to OpenVMS V7.2, the maximum permissible size of the bitmap requires larger cluster factors as volume sizes increase. Starting with V7.2, the bitmap can be larger, and cluster factors as small as one block can be used. The number of bytes in a file can be determined by multiplying the number of blocks allocated for the file times the number of bytes in a block. For sequential files (only), the FFB (XAB$W_FFB, in the File Header XAB) value can be used to find out how much of the last (XAB$L_EBK) block is used. FFB and EBK are meaningful only for sequential files, and only in a limited context-partial block allocations are not permitted. For other file formats, the EOF marker is not meaningful. Disk allocations always occur only in units of the cluster factors, which can be from one block up to (potentially) clusters of eighteen blocks or more, depending on the volume cluster factor. (OpenVMS V7.2 and later optionally provide for a cluster factor of one up to volumes of approximately 137 gigabytes.) OpenVMS assumes that the device driver and the underlying storage device will present the file system with addressable units of storage of 512 bytes in size, or the appearance of same. Various third-party CD-ROM devices, for instance, support only 2048 byte blocks, and such devices are incompatible with the standard OpenVMS device drivers. To determine the number of bytes required for a file from DCL, one option uses the f$file_attributes item EOF, multiplied by the size of a block in bytes (512). This does not account for the unused space in the last block of a sequential file, but it also does not have to differentiate sequential files from other files. 2-20 General Information _____________________________ 2.16.2 How many bytes are in a memory page? A memory page is the minimum unit of memory allocation in OpenVMS. With OpenVMS VAX, the memory page size matches the disk block size: it is always 512 bytes. With OpenVMS Alpha, the memory page size is variable, and it can range from 8192 bytes (8 kilobytes) up to 64 kilobytes. The current system page size can be determined using the sys$getsyi or f$getsyi PAGE_SIZE item. Programs with hardcoded constants for the memory page size (or page alignment) should always assume a page size of 64 kilobytes. On OpenVMS Alpha, a 512 byte area of memory-equivilent in size to an OpenVMS VAX memory page-is refered to as a pagelet. _____________________________ 2.16.3 How do I convert? Disk Blocks? KB, MB, GB, TB? The smallest granularity of disk storage addressing is called a disk block, or sometimes a disk sector. Groups of disk blocks are usually organized together into the smallest unit of storage that can be allocated, and this unit is called a disk cluster. The number of blocks in a cluster is the cluster factor, and is established when the disk volume is initialized. Each individual disk block is composed of five hundred twelve (512) bytes, or one-half kilobyte. Each byte is comprised of eight bits. A bit represents the smallest unit of information, typically refered to as a one or a zero. OpenVMS tends to uses base two notation for disk storage, while disk storage capacity specifications from most storage vendors (including Compaq) will generally use base ten notation. An OpenVMS disk block is 512 bytes in size; this is one-half kilobyte in base two notation. 2-21 General Information The following table describes the prefix, the abbreviation, and the associated base ten (marketing) and base two (OpenVMS) values. Base Ten Base Two ----------------------------- ---------------------- Kilobyte (KB) 10**3 1000 2**10 1024 Megabyte (MB) 10**6 1000000 2**20 1048576 Gigabyte (GB) 10**9 1000000000 2**30 1073741824 Terabyte (TB) 10**12 1000000000000 2**40 1099511627776 Petabyte (PB) 10**15 1000000000000000 2**50 1125899906842624 The base ten representation of the 2**40 value is 1099511627776, which is obviously rather ugly. When viewed as a base eight or base sixteen (octal or hexadecimal, respectively) value, the value is far nicer. Specifically, the value is 10000000000 and 40000000 when represented in octal and hexadecimal, respectively. Notational note: Within the OpenVMS FAQ, a thousand bits (either assuming base two or base ten, as determined by the context) is refered to as kilobit, and is always represented by the appreviation Kb, while a Kilobyte is always represented as KB. Similar notational usage also holds for Megabits (Mb) and Megabytes (MB), and for the various other units. OpenVMS operating system references to system and storage are generally to the base-two version (eg: 1024, in the case of a kilobyte or kilobit) while storage hardware references and hardware specifications are generally to the base-ten version (eg: 1000). To convert OpenVMS disk blocks to (base two) kilobytes (KB; 1024 bytes), simply divide by two. To convert blocks to (base two) megabytes, divide by 2048. Blocks to (base two) gigabytes (GB), divide by 2097152. These particular divisions can also be performed using bitshifts: to divide a value by two, shift the binary value rightward by one bit position. To convert OpenVMS disk blocks to (base ten) kilobytes, divide by approximately 1.953125. 2-22 General Information For those folks with an interest in odd applications for prefixes, and particularly for those folks also rummaging around deep within the system parameter listings, a microfortnight is approximately one second. 2-23 _______________________________________________________ 3 Documentation __________________________________________________________ 3.1 Where can I find online copies of OpenVMS manuals? The HP OpenVMS and HP Layered Product documentation is copyrighted material. HTML format on-line product documentation sets for specific HP OpenVMS products are presently available at: o http://www.openvms.compaq.com/doc/ o http://www.openvms.compaq.com/commercial/ Documentation is offered on separately orderable CD-ROM media through a subscription to the Consolidated On- Line Documentation (ConOLD) product (see Section 2.5.) ConOLD manuals are readable with BNU, a viewer that is supplied with the documentation distribution. BNU can display HTML, Bookreader, and documentation in other formats. MGBOOK, a viewer for Bookreader-format documentation is available for character-cell terminals (eg. VTxxx) via the WKU VMS Freeware file server - see question Section 13.1 for details. __________________________________________________________ 3.2 What online information and websites are available? On your OpenVMS system, the HELP command can provide a wealth of information, not only on DCL commands but on system services (HELP System_Services) and Run-Time Library routines (HELP RTL_Routines). The introduction displayed when you type the HELP command with no additional keywords provides further pointers. OpenVMS Marketing runs a WWW server at http://www.openvms.compaq.com/. Here, you will find product information, strategy documents, product 3-1 Documentation roadmaps, the contents of the latest OpenVMS Freeware CD-ROM and more. ________________________________________________________________ Table 3-1 OpenVMS Websites _______________________________________________________ URL_______Sponsor______________________________________ http://www.openvms.compaq.com/ http://www.hp.com/go/openvms/wizard/ HP OpenVMS Marketing http://www.openvmshobbyist.org/ Encompass DFWCUG http://www.levitte.org/~ava/ Arne Vajhøj http://www.saiga.com/ Saiga Systems http://www.tachysoft.com/ Wayne Sewel http://www.progis.de/openvms.htm Sponsored by proGIS Software http://www.jcameron.com/vms/ Jeff Cameron http://seqaxp.bio.caltech.edu/www/soft_doc.html David Mathog's (useful) information about OpenVMS. Cracking http://www.vistech.net/users/beave/hack-vms-faq "The Beave" Includes system cracking information that can be of interest to OpenVMS System Managers, and to OpenVMS Network and Security Managers. Undocumented Features http://www.decus.de:8080/www/vms/qaa/undoc.htmlx DECUS Deutchland http://www.levitte.org/~ava/vms_tip.htmlx 3-2 Documentation ________________________________________________________________ Table 3-1 (Cont.) OpenVMS Websites _______________________________________________________ URL_______Sponsor______________________________________ Arne Vajhøj http://www.hp.com/go/openvms/freeware/ The OpenVMS Freeware contains various examples of undocumented features and interfaces Bibliographies http://www.levitte.org/~ava/vms_book.htmlx Introductory http://www.levitte.org/~ava/vms_faq.htmlx http://seqaxp.bio.caltech.edu/www/vms_sheet.html http://seqaxp.bio.caltech.edu/www/vms_beginners_ faq.html Programming http://www.pdv-systeme.de/users/martinv/VMS_ Programming_FAQ.html An OpenVMS Programming FAQ Networking http://www.tmesis.com/internet/ Tutorial information and tips for connecting OpenVMS systems to the Internet http://www.hp.com/go/openvms/wizard/ Documentation and Specifications for DECnet Phase IV HP OpenVMS Documentation http://www.openvms.compaq.com/doc/ http://www.openvms.compaq.com/commercial/ Various introductory guides as well as more advanced manuals are available in the OpenVMS and layered product documentation set. http://www.compaq.com/info/spd/ 3-3 Documentation ________________________________________________________________ Table 3-1 (Cont.) OpenVMS Websites _______________________________________________________ URL_______Sponsor______________________________________ Software Product Descriptions (SPDs) for most every OpenVMS-related product HP sells. System Performance See Section 14.2. Patch (ECO) Kits For the HP Services FTP server hosting Various contract-access and non-contract access ECO (patch) kits, see section Section 5.16. Catalogs and Pricing http://www.compaq.com/products/quickspecs/productbulletin.html HP Product QuickSpecs and product information http://www.compaq.com/products/quickspecs/soc_ archives/SOC_Archives.html The HP Systems and Options Catalog (SOC) archive http://www.businesslink.compaq.com/ Pointers to country-specific product information, pricing, and related. The services formerly provided by BusinessLink are being replaced by these and other country-specific mechanisms, please see the URL for details. Publications http://www.openvms.compaq.com/openvmstimes/ The OpenVMS Times Newsletter http://www.dfwcug.org/ The DFWCUG Quadwords Newsletter http://www.research.compaq.com/wrl/DECarchives/DTJ/ Back issues of the (discontinued) Digital Technical Journal (DTJ) http://www.compaq.com/inFORM/ 3-4 Documentation ________________________________________________________________ Table 3-1 (Cont.) OpenVMS Websites _______________________________________________________ URL_______Sponsor______________________________________ The HP (Compaq) inFORM Magazine Hardware and Software Archives http://vax.sevensages.org/index.html The VAXarchive, including hardware and software information http://www3.sympatico.ca/n.rieck/docs/alpha_diary.html A VAX to Alpha upgrade diary http://www.montagar.com/~patj/dec/hcps.htm Scanned versions of old DIGITAL manuals from DFWCUG http://www.digital.com/lists/master-index.html http://www.compaq.com/support/techpubs/qrg/index.html A wide variety of HP VAX, Alpha, platform and other product documentation. Some ___________________introductory,_some_technical.________________ __________________________________________________________ 3.3 OpenVMS Product Information Telephone Numbers? Information on HP hardware, software, products and services is available through telephone numbers listed in Table 3-2: ________________________________________________________________ Table 3-2 Telephone Numbers _______________________________________________________ Telephone_________Description__________________________ 1-800-AT-COMPAQ HP (Compaq, including DIGITAL and Tandem) products and services _________1-800-STORWORK____The_HP_StorageWorks_team_____________ 3-5 Documentation __________________________________________________________ 3.4 How do I extract the contents of a HELP topic to a text file? To extract all the text of a HELP topic (and its subtopics) to a text file for perusal with a text editor, printing out, etc., use the following command: $ HELP/OUT=filename.txt help-topic [help-subtopic] If the help text you want is not in the standard help library (for example, it's help for a utility such as MAIL that has its own help library), add /LIBRARY=libname after the HELP verb. To see the names of help library files, do a directory of SYS$HELP:*.HLB. __________________________________________________________ 3.5 Does OpenVMS Marketing have an e-mail address? Yes - if you can't get the answers to marketing questions elsewhere, if you have comments or complaints about OpenVMS, send mail to openvms-info@compaq.com. This address is not a support channel, and is solely intended to provide informal method to communicate directly with members of OpenVMS Marketing. __________________________________________________________ 3.6 Where can I learn about OpenVMS executive internals? The OpenVMS Internals and Data Structure manual (IDSM) explains how the OpenVMS executive works. The book covers the operating system kernel: process management; memory management; the I/O subsystem; and the mechanisms that transfer control to, from, and among these. It gives an overview of a particular area of the system, followed by descriptions of the data structures related to that area and details of the code that implements the area. The first edition of the OpenVMS Alpha internals book describes Version 1.5. Although there have been several releases of OpenVMS Alpha since Version 1.5 (V6.1, V6.2, V7.0, V7.1, etc) and many details in the book are no longer accurate, it continues to provide a strong conceptual description of OpenVMS internals. 3-6 Documentation This book has been split into five pieces, each to be updated separately. The first such volume, published in early 1997, was "OpenVMS Alpha Internals and Data Structures: Scheduling and Process Control," which covers the Version 7.0 implementation of true multithreading and the changed scheduling model it implies. The internals books are available through Digital Press, see Section 3.7 __________________________________________________________ 3.7 Where can new users find tutorial information about OpenVMS? First, see if your local site has information on this topic. Each site can have site-specific features and configuration. Some sites will have site-specific new user's documentation, covering various site-specific things that are difficult or impossible for the general OpenVMS documentation to cover. _____________________________ 3.7.1 Tutorial Websites? Various websites with OpenVMS information are available; Table 3-3 contains some suggested URLs. ________________________________________________________________ Table 3-3 OpenVMS Tutorial Websites _______________________________________________________ URL_______Sponsor______________________________________ Introductory http://www.levitte.org/~ava/vms_faq.htmlx http://seqaxp.bio.caltech.edu/www/vms_sheet.html http://seqaxp.bio.caltech.edu/www/vms_beginners_ faq.html Various introductory materials http://www.montagar.com/openvms_class/ 3-7 Documentation ________________________________________________________________ Table 3-3 (Cont.) OpenVMS Tutorial Websites _______________________________________________________ URL_______Sponsor______________________________________ Members of the Encompass DFWCUG maintain a website with many materials available, including an Overview of OpenVMS, an Introduction to DCL and the TPU Editor, Advanced DCL Command Procedures, OpenVMS Operations: Batch, Print, Tape, an Introduction to OpenVMS Management, to OpenVMS User Management, to OpenVMS Network Management, and to OpenVMS Cluster Management. These training materials have been presented at various DECUS symposia. HP OpenVMS Documentation http://www.openvms.compaq.com/doc/ http://www.openvms.compaq.com/commercial/ Various introductory guides as well as more advanced manuals are available in the OpenVMS and layered product documentation set. HP OpenVMS Training http://www.compaq.com/training/home.html http://www.openvms.compaq.com/wbt/index.html HP offers training information and Technical Resource Kits (TRKs) and other Training for OpenVMS. An OpenVMS certification (testing) program is also available. http://www.jcameron.com/vms/ An OpenVMS Quiz http://www.CCSScorp.com/ CCSS Interactive Learning has OpenVMS training materials http://www.acersoft.com/ AcerSoft Training information, and Shannon Knows Punditry http://www.mindiq.com/ 3-8 Documentation ________________________________________________________________ Table 3-3 (Cont.) OpenVMS Tutorial Websites _______________________________________________________ URL_______Sponsor______________________________________ ___________________MindIQ_training_information__________________ _____________________________ 3.7.2 Books and Tutorials? Some of the OpenVMS books that are or have been available from the Digital Press imprint o http://www.bh.com/ are listed in Table 3-4: ________________________________________________________________ Table 3-4 DP Books _______________________________________________________ Title_and_Author__________________________ISBN_________ Introduction to OpenVMS, 5th Edition 1 55558 194 3 Lesley Ogilvie Rice Introduction to OpenVMS 1 878956 61 2 David W Bynon OpenVMS Alpha Internals: Scheduling and 1 55558 156 0 Process Control OpenVMS AXP Internals and Data 1 55558 120 X Structures: Version 1.5 OpenVMS System Management Guide 1 55558 143 9 Richard Berry The OpenVMS User's Guide, Second Edition 1 55558 203 6 Patrick Holmay Using DECwindows Motif for OpenVMS 1 55558 114 5 Margie Sherlock VAX/VMS Internals and Data Structures: 1 55558 059 9 Version 5.2 Writing Real Programs in DCL, Second 1 55558 191 9 Edition _________Hoffman_and_Anagnostopoulos____________________________ For various featured OpenVMS books, also please see: 3-9 Documentation o http://www.openvms.compaq.com/openvms/books.html For a bibliography of various OpenVMS books, please see: o http://www.levitte.org/~ava/vms_book.htmlx __________________________________________________________ 3.8 What OpenVMS mailing lists are available? Various OpenVMS mailing lists are available, with some of the available lists detailed in Table 3-5. ________________________________________________________________ Table 3-5 OpenVMS Mailing Lists _______________________________________________________ Subscription______________________________Interest_Area OpenVMS Freeware archive announcement FSupdate@goatley.com list FSupdate- request@goatley.com[1] Two-way echo of vmsnet.internals VMSnet- Internals@goatley.com VMSnet- Internals- request@goatley.com[1] OpenVMS Alpha Internals discussions Alpha- IDS@goatley.com Alpha-IDS- request@goatley.com[1] BLISS discussions BLISSters@goatley.com BLISSters- request@goatley.com[1] _______________________________________________________ [1]This is the subscription address. Usually, you will want to send a mail message with no subject line, and a SUBSCRIBE or HELP command in the body of the mail message. 3-10 Documentation ________________________________________________________________ Table 3-5 (Cont.) OpenVMS Mailing Lists _______________________________________________________ Subscription______________________________Interest_Area Process Software MultiNet mailing list Info- (news gateway) MultiNet@process.com Info- MultiNet- request@process.com[1] Process Software TCPware mailing list Info- (news gateway) TCPware@process.com Info-TCPware- request@process.com[1] Process Software PMDF mailing list (news Info- gateway) PMDF@process.com Info-PMDF- request@process.com[1] The SRI CHARON-VAX VAX emulator package CHARON-VAX- Users@process.com CHARON- VAX-Users- request@process.com[1] Info-Zip's Zip & UnZip discussion list Info- Zip@wku.edu Info-Zip- Request@wku.edu[1] RADIUS-VMS, a RADIUS server for OpenVMS radius- discussion forum vms@dls.net radius-vms- request@dls.net[1] _______________________________________________________ [1]This is the subscription address. Usually, you will want to send a mail message with no subject line, and a SUBSCRIBE or HELP command in the body of the mail message. 3-11 Documentation ________________________________________________________________ Table 3-5 (Cont.) OpenVMS Mailing Lists _______________________________________________________ Subscription______________________________Interest_Area Internet Service Providers (ISPs) vms- running OpenVMS isps@dls.net vms-isps- request@dls.net[1] Users of Mark Daniel's WASD web server http://wasd.vsm.com.au/ for OpenVMS VAX and Alpha exists. Information about this list server and details on how to subscribe to the list are available at the referenced website. VMS Forum http://www.neurophys.wisc.edu/comp/ava/vms_ forum.htmlx _______________________________________________________ [1]This is the subscription address. Usually, you will want to send a mail message with no subject line, and a SUBSCRIBE or HELP command in the body of the mail message. ________________________________________________________________ __________________________________________________________ 3.9 What is this Ask The Wizard website I've heard about? The HP OpenVMS Ask The Wizard (ATW) website is an informal area containing questions and answers on a wide variety of topics. o http://www.hp.com/go/openvms/wizard/ For additional information on the OpenVMS Ask The Wizard (ATW) area and for a pointer to the available ATW Wizard.zip archive, please see Section 3.9. To access a cited topic directly, use the URL filename WIZ_topic-number.HTML. For example, topic (1020) can be accessed directly using the URL filename wiz_1020.html at the following URL: o http://www.hp.com/go/openvms/wizard/ 3-12 Documentation A zip archive (named wizard.zip) containing all of the available topics and questions can be downloaded from the above URL. The wizard.zip zip archive is completely regenerated when new batches of topics are posted out to the ATW website. Before posting a question to the Ask The Wizard area, please read and please heed the posting rules- and please remember to search this document, the OpenVMS FAQ. And if you have a question that requires an answer, or if your question has time-critical constraints or business constraints, please contact the HP customer support center directly. __________________________________________________________ 3.10 Access to the OpenVMS Netscape Navigator documentation? The documentation URLs embedded into the browser itself may not operate correctly in all cases, and (for reasons not worthy of repeating here) redirects may not be available. You can manually access the documentation via: o http://www.openvms.compaq.com:88/netscape/help/ For information on the Mozilla web browser, please see Section 13.3. 3-13 _______________________________________________________ 4 Time and Timekeeping __________________________________________________________ 4.1 UTC vs GMT vs vs UT1/UT1/UT2 TDF? What are these acronyms? The results of an international compromise-though some would say an international attempt to increase confusion-UTC is refered to as "Coordinated Universal Time" (though not as CUT) in English and as "Temps Universel Coordinné" (though not as TUC) in French. (No particular information exists to explain why UTC was chosen over the equally nonsensical TCU, according to Ulysses T. Clockmeister, one of the diplomats that helped establish the international compromise.) Universal Time UT0 is solar time, UT1 is solar time corrected for a wobble in the Earth's orbit, and UT2 is UT1 corrected for seasonal rotational variations in rotation due to the Earth's solar orbit. GMT-Greenwich Mean Time-is UT1. GMT is the time at the classic site of the since-disbanded Royal Greenwich Observatory; at the most widely-known tourist attraction of Greenwich, England. UTC is based on an average across multiple atomic clocks, and is kept within 0.9 seconds of GMT, through the insertion (or removal) of seconds. In other words, UTC matches GMT plus or minus up to 0.9 seconds, but UTC is not GMT. TDF is the Timezone Differential Factor, the interval of time between the local time and UTC. Areas that celebrate daylight savings time (DST) will see periodic changes to the TDF value, when the switch-over between daylight savings time and standard time occurs. The switch-over itself is entirely left to local governmental folks, and can and has varied by political entity and politics, and the switch-over has varied over the years even at the same location. 4-1 Time and Timekeeping If your local OpenVMS system time is off by one hour (or whatever the local DST change) for some or all applications, you probably need to reset your local TDF. (For related details, please see sections Section 4.4 and Section 10.22.1.) Further discussions of history and politics, the Royal Observers' outbuildings, and the compromise that left the English with the Time Standard (the Prime Meridian) and the French with the standards for Distance and Weight (the Metric System) are left to other sources. Some of these other sources include the following URLs: o ftp://elsie.nci.nih.gov/pub/ o http://physics.nist.gov/GenInt/Time/time.html o http://nist.time.gov/ __________________________________________________________ 4.2 A brief history of OpenVMS Timekeeping, please? Why does OpenVMS regards November 17, 1858 as the beginning of time... The modified Julian date adopted by the Smithsonian Astrophysical Observatory (SAO) for satellite tracking is Julian Day 2400000.5, which turns out to be midnight on November 17, 1858. SAO started tracking satellites with an 8K (nonvirtual) 36-bit IBM 704 in 1957 when Sputnik went into orbit. The Julian day was 2435839 on January 1, 1957. This is 11225377 octal, which was too big to fit into an 18-bit field. With only 8K of memory, the 14 bits left over by keeping the Julian date in its own 36-bit word would have been wasted. SAO also needed the fraction of the current day (for which 18 bits gave enough accuracy), so it was decided to keep the number of days in the left 18 bits and the fraction of a day in the right 18 bits of one word. Eighteen bits allows the truncated Julian Day (the SAO day) to grow as large as 262143, which from November 17, 1858, allowed for 7 centuries. Possibly, the date could only grow as large as 131071 (using 17 bits), but this still covers 3 centuries and leaves the 4-2 Time and Timekeeping possibility of representing negative time. The 1858 date preceded the oldest star catalogue in use at SAO, which also avoided having to use negative time in any of the satellite tracking calculations. The original Julian Day (JD) is used by astronomers and expressed in days since noon January 1, 4713 B.C. This measure of time was introduced by Joseph Scaliger in the 16th century. It is named in honor of his father, Julius Caesar Scaliger (note that this Julian Day is different from the Julian calendar that is named for the Roman Emperor Julius Caesar!). Why 4713 BC? Scaliger traced three time cycles and found that they were all in the first year of their cyle in 4713 B.C. The three cycles are 15, 19, and 28 years long. By multiplying these three numbers (15 * 19 * 28 = 7980), he was able to represent any date from 4713 B.C. through 3267 A.D. The starting year was before any historical event known to him. In fact, the Jewish calendar marks the start of the world as 3761 B.C. Today his numbering scheme is still used by astronomers to avoid the difficulties of converting the months of different calendars in use during different eras. The following web sites: o http://www.openvms.compaq.com/openvms/products/year- 2000/leap.html o http://www.eecis.udel.edu/~ntp/ o http://www.nist.gov/ o http://www.boulder.nist.gov/timefreq/ o http://www.tondering.dk/claus/calendar.html o http://es.rice.edu/ES/humsoc/Galileo/Things/gregorian_ calendar.html are all good time-related resources, some general and some specific to OpenVMS. 4-3