=;The OpenVMS Frequently Asked Questions (FAQ)D

The OpenVMS Frequently Asked Questions (FAQ)



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3.3 How do I extract the contents of a HELP topic to a text file?



FTo extract all the text of a HELP topic (and its subtopics) to a text Afile for perusal with a text editor, printing out, etc., use the following command:

 

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3$ HELP/OUT=filename.txt help-topic [help-subtopic] 




CIf the help text you want is not in the standard help library (for Dexample, it's help for a utility such as MAIL that has its own help Hlibrary), add /LIBRARY=libname after the HELP verb. To see the names of 5help library files, do a directory of SYS$HELP:*.HLB.h

3.4 Does OpenVMS Marketing have an e-mail address?



HYes - if you can't get the answers to marketing questions elsewhere, if <you have comments or complaints about OpenVMS, send mail to Copenvms-info{atsign}hp.com. This address is not a support >channel, and is solely intended to provide informal method to 7communicate directly with members of OpenVMS Marketing.o

3.5 Where can I learn about OpenVMS executive internals?



HThe OpenVMS Internals and Data Structure manual (IDSM) explains how the FOpenVMS executive works. The book covers the operating system kernel: Bprocess management; memory management; the I/O subsystem; and the Hmechanisms that transfer control to, from, and among these. It gives an Foverview of a particular area of the system, followed by descriptions Dof the data structures related to that area and details of the code that implements the area.

HThe first edition of the OpenVMS Alpha internals book describes Version F1.5. Although there have been several releases of OpenVMS Alpha since GVersion 1.5 (V6.1, V6.2, V7.0, V7.1, etc) and many details in the book Dare no longer accurate, it continues to provide a strong conceptual !description of OpenVMS internals.

>This book has been split into five pieces, each to be updated @separately. The first such volume, published in early 1997, was E"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 3.6w

3.6 Where can new users find tutorial information about OpenVMS?



GFirst, see if your local site has information on this topic. Each site Hcan have site-specific features and configuration. Some sites will have Gsite-specific new user's documentation, covering various site-specific @things that are difficult or impossible for the general OpenVMS documentation to cover.7

3.6.1 Tutorial Websites?



Various websites with OpenVMS information are available; Table 3-2 contains some suggested URLs.

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Table 3-2 OpenVMS Tutorial and Documentation Websites
URL Sponsor
# Introductory
; / http://www.levitte.org/~ava/vms_faq.htmlx
; / http://saf.bio.caltech.edu/vms_sheet.html
J > http://seqaxp.bio.caltech.edu/www/vms_beginners_faq.html
  $ Various introductory materials
8 , http://www.montagar.com/openvms_class/
  M Members of the Encompass DFWCUG maintain a website with many materials N available, including an Overview of OpenVMS, an Introduction to DCL and K the TPU Editor, Advanced DCL Command Procedures, OpenVMS Operations: L Batch, Print, Tape, an Introduction to OpenVMS Management, to OpenVMS M User Management, to OpenVMS Network Management, and to OpenVMS Cluster J Management. These training materials have been presented at various  DECUS symposia.
E 9 http://www.mcsr.olemiss.edu/unixhelp/VMStoUNIX.html
  I A comparison table of various command-level tasks, with information % % % N on the UNIX and Linux shell command(s), and on the OpenVMS DCL  command(s).
/ HP OpenVMS Documentation
3 ' http://www.hp.com/go/openvms/doc/
  G Various introductory guides as well as more advanced manuals are E available in the OpenVMS and layered product documentation set.
* HP OpenVMS Training
: . http://www.compaq.com/training/home.html 
> 2 http://www.openvms.compaq.com/wbt/index.html
  L HP offers training information and Technical Resource Kits (TRKs) and M other Training for OpenVMS. An OpenVMS certification (testing) program  is also available.
J http://www.jcameron.com/vms/
   An OpenVMS Quiz
B http://www.CCSScorp.com/
  > CCSS Interactive Learning has OpenVMS training materials
B http://www.acersoft.com/
  ? AcerSoft Training information, and Shannon Knows Punditry
> http://www.mindiq.com/
  ! MindIQ training information
D http://www.quadratrix.be/
  K Quadratrix; OpenVMS training, products and services; affiliated with ! Global Knowledge and KeyJob
9

3.6.2 Books and Tutorials?



CSome of the OpenVMS books that are or have been available from the Digital Press imprint



Gare listed in Table 3-3:

S  +                                               
Table 3-3 DP Books
Title and Author ISBN
A Getting Started with OpenVMS System Management, 2nd Edition%
David Donald Miller, et al
 1-55558-243-5
* Introduction to OpenVMS, 5th Edition
Lesley Ogilvie Rice
 1-55558-194-3
 Introduction to OpenVMS
David W Bynon
 1-878956-61-2
= OpenVMS Alpha Internals: Scheduling and Process Control  1-55558-156-0
< OpenVMS AXP Internals and Data Structures: Version 1.5  1-55558-120-X
% OpenVMS System Management Guide
Baldwin, et al
 1-55558-143-9
. The OpenVMS User's Guide, Second Edition
Patrick Holmay
 1-55558-203-6
( Using DECwindows Motif for OpenVMS
Margie Sherlock
 1-55558-114-5
8 VAX/VMS Internals and Data Structures: Version 5.2  1-55558-059-9
2 Writing Real Programs in DCL, Second Edition&
Hoffman and Anagnostopoulos
 1-55558-191-9
/ Writing OpenVMS Alpha Device Drivers in C!
Sherlock and Szubowicz
 1-55558-133-1


FFor various featured OpenVMS books, also please see the books link at the OpenVMS website:



8For a bibliography of various OpenVMS books, please see:

d

3.7 What OpenVMS mailing lists are available?



HVarious OpenVMS mailing lists are available, with some of the available Hlists detailed in Table 3-4.

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Table 3-4 OpenVMS Mailing Lists
Subscription Interest Area
0 OpenVMS Freeware archive announcement list  FSupdate@goatley.com'
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
; Process Software MultiNet mailing list (news gateway)  Info-MultiNet@process.com,
Info-MultiNet-request@process.com 1
: Process Software TCPware mailing list (news gateway)  Info-TCPware@process.com+
Info-TCPware-request@process.com 1
7 Process Software PMDF mailing list (news gateway)  Info-PMDF@process.com(
Info-PMDF-request@process.com 1
I The Software Resources International (SRI) CHARON-VAX VAX emulator package % % " CHARON-VAX-Users@process.com/
CHARON-VAX-Users-request@process.com 1
0 Info-Zip's Zip & UnZip discussion list  Info-Zip@wku.edu
 ' Info-Zip-Request@wku.edu 1
? RADIUS-VMS, a RADIUS server for OpenVMS discussion forum  radius-vms@dls.net%
radius-vms-request@dls.net 1
7 Internet Service Providers (ISPs) running OpenVMS  vms-isps@dls.net#
vms-isps-request@dls.net 1
G Users of Mark Daniel's WASD web server for OpenVMS VAX and Alpha G exists. Information about this list server and details on how to D subscribe to the list are available at the referenced website. @ http://wasd.vsm.com.au/
 VMS Forum H < http://www.neurophys.wisc.edu/comp/ava/vms_forum.htmlx



H1This is the subscription address. Usually, you will want to Bsend a mail message with no subject line, and a SUBSCRIBE or HELP (command in the body of the mail message.

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3.8 What is this Ask The Wizard website I've heard about?



#The HP OpenVMS Ask The Wizard (ATW)Fwebsite was an informal area discussing OpenVMS, containing questions (and answers on a wide variety of topics.



HFor additional information on the OpenVMS Ask The Wizard (ATW) area and Bfor a pointer to the available ATW Wizard.zip archive, please see 0Section 3.8.

7To access a cited topic directly, use the URL filename HWIZ_topic-number.HTML, or use the topic search engine. Cited topics are Fshown in parentheses, and act as unique topic addresses. These should Gnot be confused with the relative topic numbers shown at the site. For Aexample, the topic (1020) can be accessed directly using the URL Hfilename wiz_1020.html, at the web site that the following URL resolves into:



HA zip archive (named wizard.zip) containing all of the available topics Band questions can be downloaded from the above URL. The wizard.zipF zip archive is completely regenerated when/if existing topics posted G out to the ATW website are updated. Copies of this wizard.zip archive : also generally ship out on the OpenVMS Freeware, as well.

ENew (informal) questions and discussions are now being directed away from the ATW area to the; ITRC area, and specifically to the ITRC discussion forums:

t

3.9 Where can I find the latest C run-time library manuals?



DThe C run-time library (RTL) reference documentation has been moved Hfrom the C language documentation set to the OpenVMS documentation set. GFor the most recent version of the C RTL documentation and the OpenVMS 3standard C library, please see the OpenVMS manuals.

FIn addition to the user-mode C RTL, there is a second kernel-mode RTL Gaccessable to drivers on OpenVMS Alpha and OpenVMS I64. For details on Cthis second library and on the duplicate symbol errors that can be 4triggered when this library is referenced during an jincorrectly-specified LINK command, please see Section 10.22.1. For Cgeneral information on this kernel RTL, see the Digital Press book AWriting OpenVMS Device Drivers in C. For details, please see the 0associated OpenVMS source listings distribution.




A

Chapter 4
Time and Timekeeping


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If you are searching for something here, please (consider using the text-format FAQ.



GThis chapter discusses time, timekeeping, system time synchronization, 2clock skew and clock drift, implications of using 5SUBMIT/AFTER=TOMORROW, and other time-related topics.j

4.1 A brief history of OpenVMS Timekeeping, please?



FWhy does OpenVMS regards November 17, 1858 as the beginning of time...

BThe modified Julian date adopted by the Smithsonian Astrophysical Observatory (SAO)/for satellite tracking is Julian Day 2400000.5,4which turns out to be midnight on November 17, 1858.

GSAO started tracking satellites with an 8K (nonvirtual) 36-bit IBM 704 Din 1957 when Sputnik went into orbit. The Julian day was 2435839 on GJanuary 1, 1957. This is 11225377 octal, which was too big to fit into Ban 18-bit field. With only 8K of memory, the 14 bits left over by Gkeeping the Julian date in its own 36-bit word would have been wasted. HSAO also needed the fraction of the current day (for which 18 bits gave Fenough accuracy), so it was decided to keep the number of days in the Hleft 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) toEgrow as large as 262143, which from November 17, 1858, allowed for 7 Hcenturies. Possibly, the date could only grow as large as 131071 (using G17 bits), but this still covers 3 centuries and leaves the possibility Fof representing negative time. The 1858 date preceded the oldest star Hcatalogue in use at SAO, which also avoided having to use negative time .in any of the satellite tracking calculations.

EThe original Julian Day (JD) is used by astronomers and expressed in >days since noon January 1, 4713 B.C. This measure of time was Aintroduced 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 calendar4that is named for the Roman Emperor Julius Caesar!).

HWhy 4713 BC? Scaliger traced three time cycles and found that they were Fall in the first year of their cyle in 4713 B.C. The three cycles are G15, 19, and 28 years long. By multiplying these three numbers (15 * 19 G* 28 = 7980), he was able to represent any date from 4713 B.C. through 3267 A.D.

CThe starting year was before any historical event known to him. In Dfact, the Jewish calendar marks the start of the world as 3761 B.C. EToday his numbering scheme is still used by astronomers to avoid the Ddifficulties of converting the months of different calendars in use during different eras.

The following web sites:



Gare all good time-related resources, some general and some specific to OpenVMS.O

4.1.1 Details of the OpenVMS system time-keeping?

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4.1.1.1 VAX hardware time-keeping details...

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4.1.1.1.1 TOY clock

EThis is battery backed up hardware timing circuitry used to keep the Bcorrect time of year during rebooting, power failures, and system Eshutdown. This clock only keeps track of months, days, and time. The Etime is kept relative to January 1st, at 00:00:00.00 of the year the clock was initiailized.

FThe VAX Time-Of-Year (TOY) clock (used to save the time over a reboot For power failure) is specified as having an accuracy of 0.0025%. This +is a drift of roughly 65 seconds per month.

GThe VAX Interval Time is used to keep the running time, and this has a Bspecified accuracy of .01%. This is a drift of approximately 8.64 seconds per day.

DAny high-IPL activity can interfere with the IPL 22 or IPL 24 (this Fdepends on the VAX implementation) clock interrupts---activities such Das extensive device driver interrupts or memory errors are known to slow the clock.;

4.1.1.1.2 EXE$GQ_SYSTIME

HThis is the OpenVMS VAX system time cell. This cell contains the number Hof 100ns intervals since a known reference. This cell is incremented by 0100000 every 10ms by an hardware interval timer.9

4.1.1.1.3 EXE$GQ_TODCBASE

GThis cell contains the time and date the system time was last adjusted >by EXE$SETTIME. It uses the same format as EXE$GQ_SYSTIME. On Dadjustment of the system time a copy of EXE$GQ_SYSTIME is stored in Hthis cell in both memory and on disk. This cell is used to get the year for the system time.1

4.1.1.1.4 EXE$GL_TODR

GThis cell contains the time and date the system time was last adjusted by EXE$SETTIME.HIt uses the same format as the time of year clock. On adjustment of the Csystem time this cell gets saved back to both memory and disk. The Econtents of this cell are used to test the validity of the TOY clock.

CThe system parameters SETTIME and TIMEPROMPTWAIT determine how the system time will be set.



HWhen booting a CD-ROM containing an OpenVMS VAX system, the system will Gtypically be deliberately configured prompt the user to input the time <-- this is necessary in order to boot with the correct time.

4If either TIMEPROMPTWAIT or SETTIME are set to zero,HOpenVMS VAX will use the TOY clock to get the time of year, and the yearGwill be fetched from the distribution medium. The value of the year on Cthe distribution medium (saved within the SYS.EXE image) will most Dlikely be that of when the kit was mastered, and cannot be changed. CUnless the current year happens to be the same year as that on the Edistribution, most likely the year will be incorrect. (Further, with Gthe calculation of Leap Year also being dependent on the current year, Bthere is a possibility that the date could be incorrect, as well.)




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