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/...
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_______________________________________________________
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.
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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
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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.
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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.
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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.
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________________________________________________________________
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
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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.
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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.
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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
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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.
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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
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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.
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__________________________________________________________
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/
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__________________________________________________________
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
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________________________________________________________________
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.
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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
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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
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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.
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