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BACKUP
BACKUP
Date: May 75
File: BACKUP.RNO
Edition: 1
ABSTRACT
The BACKUP program is used to save disk
files on magnetic tape and later to
restore any or all of these files back
to disk. This document describes the
general capabilities of BACKUP. Version
1 of the software will be used by
Digital Equipment Corporation to
distribute all the software for the
DECsystem-10.
Page 2
The information in this document is subject to change without notice
and should not be construed as a commitment by Digital Equipment
Corporation. Digital Equipment Corporation assumes no responsibility
for any errors that may appear in this manual.
The software described in this document is furnished to the purchaser
under a license for use on a single computer system and can be copied
(with inclusion of DIGITAL's copyright notice) only for use in such
system, except as may otherwise be provided in writing by DIGITAL.
Digital Equipment Corporation assumes no responsibility for the use or
reliability of its software on equipment that is not supplied by
DIGITAL.
Copyright 1975, 1976, Digital Equipment Corp., Maynard, Mass.
The following are trademarks of Digital Equipment Corporation.
DEC FLIP CHIP PDP
DECsystem-10 KA10 TOPS10
DECTAPE KI10 TYPESET-8
DIGITAL KL10 TYPESET-10
Page 3
CONTENTS
1.0 INTRODUCtion 4
1.1 System Programmer Uses 4
1.2 Console User Uses 4
2.0 BACKUP COMMANDS 4
3.0 USAGE 9
3.1 The SAVE Command 9
3.2 The RESTORE Command 10
3.3 Obtaining Directories of BACKUP Tapes 10
3.4 Comparing Tape and Disk Files 11
4.0 BACKUP MESSAGES 12
4.1 Operator Messages 12
4.2 Error Messages 12
4.3 Warning Messages 14
5.0 CAPACITIES OF DISK MEDIA VERSUS MAGNETIC TAPE 17
APPENDIX TAPE FORMAT 18
Page 4
1.0 INTRODUCTION
The BACKUP program is a system program that is used for the
distribution of DECsystem-10 software.
BACKUP is more sophisticated than the previous system program for
storage of disk files on magnetic tape. It allows for more
selectivity when choosing the files to be removed from the disk.
BACKUP is able to save files occupying multiple reels of tape.
Distribution tapes for the DECsystem-10 will be produced via BACKUP.
1.1 System Programmer Uses
Version 1 of BACKUP is intended to acquaint system programmers with
BACKUP's command interface and tape format. It is for use with
distribution tapes only. BACKUP can be used to transport files from
one system to another, aiding in the distribution of newly developed
files from one installation to another.
The distribution is implemented by the interchange mode switch. When
running in interchange mode, BACKUP ignores installation dependent
data and reads and writes only the information which is critical to
the file itself. For more information on the interchange mode and
BACKUP's tape format, refer to the Appendix.
1.2 Console User Uses
The console user can execute all of the BACKUP commands on his own
disk area. He can save his disk area or any other files accessable to
him on his own magnetic tape and later restore all his files or a
subset of his files back to his area.
2.0 BACKUP COMMANDS
BACKUP commands are in the form of verbs. BACKUP prompts with a slash
(/) and has three kinds of verbs:
1. Action,
2. Status setting, and
3. Tape positioning.
The action commands take as an argument a list of file specifications
in a format similar to the monitor's COPY command. The file
specifications can contain wild-cards (e.g., ? and *). For example
to specify all files of the name COBOL and any extension, the file
specification should be "COBOL.*". The entire DEC wild-carding scheme
Page 5
works under BACKUP. Another example might be to specify all ".MAC"
files whose first three letters are "FOR"; this would look like
"FOR???.MAC."
For each entry in the list, the user can specify both input and output
file specifications (output = input) or just the input specification.
This allows the files to be renamed as they are saved or restored. If
no output specification is given, then the specified files are
transferred without being renamed. Entries in the list are separated
by commas.
The action commands operate on the tape specified by the last TAPE
verb. A tape must be specified before using any of the action
commands, or an error will result. In the following lists of commands
and switches
spec is the standard file specification
dev:filename.ext [directory]
date is in the form dd-mmm-yy
time is in the form hh:mm:ss
The action verbs are:
Command Action
CHECK spec-list Verify that the tape and disk agree
[N]PRINT spec Print a directory of the entire tape on
spec. N is an optional prefix meaning
narrow.
SAVE spec-list Save the disk onto tape
RESTORE spec-list Restore from tape to disk
The status setting commands set a parameter which will affect future
action commands. The negative form of certain commands is specified
by an optional NO preceding the command. The status setting commands
are:
Command Action
ABEFORE date Include only files accessed before the
specified date
[NO]APPEND Append to existing LOG file (default)
ASINCE date Include only files accessed since the
specified date
BEFORE date-time Include only files created and last
modified before the specified date-time
[NO]DATE75 Always accept files with possible DATE75
problems (default)
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DENSITY (200, 556, 800, (On input or output files) set tape
1600) density
DIRECTORIES Type each user's directory while running
(default)
[NO]ENCRYPT Encrypt the magtape (asks for key later)
(a key is similar to a password and it
can consist of up to 6 alphabetic
characters.)
FILES Type each filename while running
INITIAL spec Start processing at spec
[NO]INTERCHANGE Run in interchange mode. (This is a
default in version 1. A message is
printed to this effect when BACKUP
begins.)
LENGTH L:H Include only files whose length is
between Low and High
LIST spec While running, make a log file on spec
(default spec is LPT:BACKUP.LOG)
MBEFORE date-time Include only files which have been last
moved or modified before the specified
time
MSINCE date-time Include only files which have been moved
or modified since the specified time
MESSAGE [NO]PREFIX Suppress error message prefix
MESSAGE [NO]FIRST Suppress first line of error message
text
[NO]OPTION NAME Use option BACKUP:name from SWITCH.INI
PARITY (EVEN,ODD) Set tape parity.
SILENCE Do not type filenames or directories
while running
SINCE date-time Include only files created or modified
since the specified date-time
SORT DIRECTORIES X Sort directories within each file
structure in order X when saving.
X=ALPHABETICAL, LOCATION, or NONE (by
Master File Directory).
SORT FILES X Sort files within each directory in
order X when saving.
Page 7
X = ALPHABETICAL, LOCATION, OR NONE (by
directory)
SSNAME A Save set name is A (up to 30 characters;
ALL = all save sets on tape)
SUPERSEDE ALWAYS Restore version from tape
SUPERSEDE NEVER Restore from tape unless on disk
SUPERSEDE OLDER Restore only the new versions from tape
(default)
TAPE MTB0: Use tape unit MTB0
[NO]USETI Run in USETI mode (speeds up SAVES with
/SINCE, etc.)
[NO]WRITE Suppress disk writing during a RESTORE.
The tape positioning commands take immediate effect. They take, as an
argument, a list of tapes. If no tape is specified for a given
command, the last tape declared in a TAPE verb is positioned. The
tape postioning commands are:
Command Action
EOT tape list Skip to the end-of-tape mark for each
tape in the list
REWIND tape list Rewind to the beginning of the tape for
each tape in the list
SKIP n tape list Skip n save sets forward for each tape
in the list
SKIP 0 tape list Backup to the start of the current save
set for each tape in the list
SKIP -n tape list Skip n save sets backward for each tape
in the list
UNLOAD tape list Unload each tape from its drive for each
tape in the list.
Certain switches can be used for entries within the specification list
supplied for an action verb. These switches should be preceded by a
slash. They are as follows:
Switch Action
ABEFORE date (On input file) include only if accessed
before date
Page 8
ASINCE date (On input file) include only if accessed
since date
BEFORE date-time (On input file) include only if created
before date-time
ERNONE (On input file) give error if no files
match
ERPROTECTION (On input file) give error if there is a
protection failure
ESTIMATE n (On output file) estimate output size
LENGTH L:H (On input file) include only if the file
length is between L:H
MBEFORE date-time (On input file) include only if modified
before date-time
MSINCE date-time (On input file) include only if modified
since date-time
OKNONE (On input file) do not give an error if
no files match
[NO]PHYSICAL (Input or output) ignore logical names
PROTECTION nnn (On output files) set the protection
code
SINCE date-time (On input file) include only if created
since the specified date-time
VERSION v (On output files) set output file
version number
UPROTECTION nnn Set the protection codes for the User
File Directory
This group of commands can be given during the execution of the action
verbs. The prompting character is an exclamation point (!). (EXIT,
HELP, and RESET will also work with a slash (/) as a prompting
character.):
Commands Action
DIRECTORIES Start typing every directory processed
EXIT Exit from BACKUP when done
FILES Start typing every file and directory
processed
GO Continue after a STOP
Page 9
HELP List these commands and explanations
KILL Abort execution of the current action
verb
PAUSE Do not exit from BACKUP when done
RESET Reset all status settings to their
original defaults when done
SILENCE Stop typing every directory or file
STOP Stop temporarily; can be continued by
GO.
WHAT Display current filename and status
3.0 USAGE
Version 1 of BACKUP is a tool for interchanging files between
installations and is executed in interchange mode only. If the user
omits the interchange mode switch, he will receive a warning message
to that effect. This mode allows the critical information in the
files to be gleaned from the installation dependent data.
The following examples demonstrate the application of the BACKUP
program.
3.1 The SAVE Command
The command
/SAVE spec-list
saves all the files on disk that match the input side of the entry in
the specification list. BACKUP groups these files in a save set.
(Each SAVE command creates one save set on tape.) The user can name
the save set with the SSNAME status setting command.
The following sequence saves all LINK files on DSKN: 1,4 for
interchange in a save set named LINK, on a tape mounted on drive MTA0.
.R BACKUP
/TAPE MTA0:
/INTERCHANGE
/SSNAME LINK
/SAVE DSKN:[1,4]LINK.*
! 1,4 DSKN
/
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3.2 The RESTORE Command
The command
/RESTORE spec-list
restores files from tape to disk. If the user names a save set before
issuing the RESTORE command, BACKUP will restore the files from the
save set only. If the user resets the save set to ALL, BACKUP will
search all the save sets on tape.
The following example restores all files in the save set named SCAN.
.R BACKUP
/TAPE MTA0:
/REWIND
/SSNAME SCAN
/RESTORE
/
To restore all HELP files in all save sets on tape, type
/REWIND
/SSNAME ALL
/RESTORE *.HLP
!
/
3.3 Obtaining Directories of BACKUP Tapes
The command
[N]PRINT spec
prints a directory of the entire tape. The optional prefix N
indicates a narrow listing (72 columns). The default specification is
LPT:BACKUP.LOG. If a line-printer is not available to the user's job,
spooling is not in effect, and the default spec is used, an error will
occur.
The following example produces a disk file directory listing named
BACKUP.LOG.
.R BACKUP
/REWIND
/PRINT DSK:
!
/^C
Page 11
This is an example of the output.
.TYPE BACKUP.LOG
START OF SAVE SET SCAN ON MTA0 BACKUP VERSION 1(41) FORMAT 1
SYSTEM RX740B SYS #514/546 TOPS-10 MONITOR 0(60140) APR#514
800 BPI 9 TRACK
SCAN REL 58 18-MAR-75 DSK:
SCAN RNO 8 8-MAR-75
SCAN MAC 304 18-MAR-75
SCN7A DOC 99 19-MAR-75
SCN7A RND 95 19-MAR-75
END OF SAVE SET SCAN ON MTA0 BACKUP VERSION 1(41) FORMAT 1
SYSTEM RX740B SYS #514/546 TOPS-10 MONITOR 0(60140) APR#514
800 BPI 9 TRACK
START OF SAVE SET BACKUP ON MTA0 BACKUP VERSION 1(41) FORMAT 1
SYSTEM RX740B SYS #514/546 TOPS-10 MONITOR 0(60140) APR#514
800 BPI 9 TRACK
BACKUP HLP 11 18-MAR-75
BACKUP MAC 94 13-MAR-75
BACKRS MAC 174 13-MAR-75
BACKUP SHR 39 18-MAR-75
BACKUP LOW 26 18-MAR-75
BACKUP RND 6 17-MAR-75
BACKUP RNH 11 18-MAR-75
END OF SAVE SET BACKUP ON MTA0 BACKUP VERSION 1(41) FORMAT 1
SYSTEM RX740B SYS #514/546 TOPS-10 MONITOR 0(60140) APR#514
800 BPI 9 TRACK
3.4 Comparing Tape and Disk Files
The command
CHECK spec-list
verifies that the tape and disk agree. BACKUP compares the tape files
specified for input to the disk files specified for output, word for
word.
The following example saves all the user's COBOL files on tape and
then verifies that the saved tape files are identical to the disk
files.
Page 12
.R BACKUP
/TAPE MTA0:
/REWIND
/SAVE *.CBL
/REWIND
/CHECK
!
/
TO RESTORE ALL SHR and LOW files from a tape and then verify that the
files were restored correctly type
/REWIND
/SSNAME ALL
/RESTORE *.SHR,*.LOW
!
/REWIND
/CHECK *.SHR,*.LOW
!
/
4.0 BACKUP MESSAGES
4.1 OPERATOR MESSAGES
$BKPEOT EOT REACHED -- NEED NEW TAPE
The tape is full. The operator should mount a new one and type a
carriage return to continue.
$BKPMWL TAPE WRITE LOCKED -- NEED WRITE RING
The tape is write locked. The operator should insert a write
ring and type a carriage return to continue.
4.2 ERROR MESSAGES
?BKPABC AMBIGUOUS COMMAND
The user has given a command abbreviation that is not unique.
?BKPCOL CAN'T OPEN LISTING DEVICE
The device specified for the LIST command cannot be selected for
output.
Page 13
?BKPCOM CAN'T OPEN MAGTAPE
The tape device specified cannot be selected for output.
?BKPCSA CAN'T SAVE WITH SAVE SET NAME "ALL"
"ALL" is reserved to mean all SAVE sets on tape; therefore, it
cannot be used to name an individual SAVE set when saving.
?BKPDND DEVICE NOT A DISK
The input device specified for a SAVE or the output device
specified for a RESTORE is not a disk.
?BKPDNM DEVICE NOT A MAGTAPE
The device specified for the TAPE command or a tape positioning
command is not a magnetic tape drive.
?BKPFSL FILE SPECIFICATION DATA LOST
During the processing of a file specification list, a consistency
check determined that data was lost. If this error occurs,
please send an SPR.
?BKPHSG CANNOT GET HIGH SEGMENT BACK
BACKUP releases its high segment command scanner when performing
I/O to eliminate most of the core while running. The attempt to
restore the high segment after completing the I/O operation has
failed.
?BKPIRC INVALID RUN TIME COMMAND -- TYPE KILL TO ABORT RUN FIRST
The user typed an illegal run time command. Type KILL to abort
the run and return to verb command level. Type HELP to get a
list of valid run time commands.
?BKPLFE LISTING FILE ENTER ERROR
After opening the listing I/O channel, no entry could be made for
the listing file.
?BKPLSI LISTING SPECIFICATION INCORRECTLY FORMATTED
The user has used incorrect formatting or a "wild-card" in
specifying the LIST file. No list specification is created.
?BKPNTS NO TAPE SPECIFIED
While searching for the last tape specification given, none could
be found.
Page 14
?BKPTMI INSUFFICIENT CORE FOR COMMAND
The routine for allocating space for file specifications could
not expand core enough to store the specification.
?BKPTSI TAPE SPECIFICATION INCORRECTLY FORMATTED
The user has used incorrect formatting or a "wild-card" in
specifying the tape device. This clears the tape specification.
4.3 WARNING MESSAGES
%BKPABT ABORT spec
The transfer of the specified file from tape to disk has been
aborted.
%BKPBTL BLOCK TOO LARGE DURING SPEC (BLOCK = n)
The current record read from tape exceeds the buffer size.
%BKPCAB CHECK ABORTED
A CHECK was aborted by the KILL command.
%BKPCCM CANNOT COPY MFD FOR STRUCTURE
The program cannot get enough core to copy the Master File
Directory for the indicated structure. Files for this structure
will not be saved, and the program will skip to the next
structure.
%BKPCCR CANNOT COPY UFD/SFD RIB FOR spec
The program cannot get enough core to copy the retrieval
information block for the indicated directory. Files for this
User File Directory/Sub-File Directory will not be saved, and the
program will skip to the next UFD/SFD.
%BKPCCU COPY UFD/SFD FOR spec
The program cannot get enough core to copy the indicated User
File Directory or Sub-File Directory. Files for this UFD or SFD
will not be saved, and the program will attempt to continue by
skipping to the next UFD/SFD.
%BKPCDS CHECK DISK FILE SHORTER spec
During a check operation, an end-of-file occurred for the
indicated disk file, even though there is more file data on tape.
Page 15
%BKPCFD CHECK FILES ARE DIFFERENT spec
The check operation determined that the disk and tape versions of
the indicated file are different.
%BKPCHK CHECKSUM INCONSISTENCY DURING spec (BLOCK = n)
During a read, the computed checksum of the current tape record
did not agree with the checksum stored when the record was
written.
%BKPCNF CHECK FILE NOT ON DISK spec
The indicated file could not be found on disk during a check
operation.
%BKPCOD CANNOT OPEN "file structure"
The file structure indicated cannot be selected for I/O. The
transfer of files for this structure will be aborted.
%BKPCTS CHECK TAPE FILE SHORTER spec
During a check operation, an end-of-file occurred for the
indicated tape file, even though there is more file data on disk.
%BKPDER DATA MISSED/ TAPE BAD/ TRANSPORT HUNG DURING spec (BLOCK = n)
One of the indicated conditions was detected by the hardware.
The transferred file may contain unreliable data.
%BKPDIO DISK I/O ERROR error bits DURING spec
A disk I/O error occurred while attempting to read or write the
specification. The error bits included are those returned by the
monitor GETSTS call. The transfer will be aborted for this file.
%BKPFEE ENTER error-code spec
File enter error for the specification. The error bits included
are those set by the monitor, and the error code abbreviation is
listed in the DECsystem-10 Monitor Calls Manual.
%BKPFLE LOOKUP error-code spec
File lookup error for the specification. The error bits included
are those set by the monitor, and the error code abbreviation is
listed in the DECsystem-10 Monitor Calls Manual.
%BKPHRI HEADER RDW INCONSISTENCY
A consistency check has determined that the tape's file data
records are not consecutive. This message is followed by
"%BKPABT ABORT spec" message reporting that the file will not be
transferred from tape to disk.
Page 16
%BKPHSI HEADER FILE SPEC INCONSISTENCY
During a restore operation, a consistency check determined that
the end-of-file record for the current file was missed, and the
current record belongs to another file. This message is followed
by "%BKPABT ABORT spec" indicating that the incomplete file will
not be transferred from tape to disk.
%BKPIBL INCORRECT BLOCK LENGTH
During a RESTORE, the program encountered a tape record of the
wrong size. The record will be skipped.
%BKPINT ONLY INTERCHANGE MODE SUPPORTED IN VERSION 1.
This message warns the user that he is running in interchange
mode.
%BKPNBF NOT BACKUP FORMAT
The current tape record is not in BACKUP format, and the program
will skip to the next tape record.
%BKPNEC NOT ENOUGH CORE
The program cannot get enough core. If this occurs during a
RESTORE, the RESTORE will be aborted. During a SAVE, the program
will skip to the next structure or User File Directory and
attempt to continue.
%BKPNFF NO FILES FOUND TO MATCH spec
No files were found to match the given file specification.
%BKPPRE PARITY ERROR DURING spec (BLOCK = n)
The hardware detected a parity error. The transferred file may
contain unreliable data.
%BKPRAB RESTORE ABORTED
A RESTORE was aborted by the KILL command.
%BKPSAB SAVE ABORTED
A SAVE was aborted by the KILL command.
%BKPSCE SIZE COPY ERROR spec
While transferring a file from tape to disk an error was
encountered because the transferred file was not the same size as
the tape file.
Page 17
%BKPSLE SFD LEVEL EXCEEDED
While attempting to save nested Sub-File Directories the SFD
level was exceeded.
%BKPSNF SAVE SET NOT FOUND name
This message may occur during a RESTORE or CHECK operation and
indicates that the save set named with the last /SSNAME verb
could not be found.
%BKPUIE UNIDENTIFIABLE INPUT ERROR
An error was encountered while trying to move data from tape to
disk.
%BKPUOE UNIDENTIFIABLE OUTPUT ERROR
An error was encountered while trying to move data from disk to
tape.
%BKPURT UNKNOWN RECORD TYPE
While reading the tape, BACKUP found that the type number of the
current tape record is not within the defined range. The program
will skip to the next tape record.
5.0 CAPACITIES OF DISK MEDIA VERSUS MAGNETIC TAPE
The following table illustrates the maximum capacity of various disk
devices and the approximate number of 2400-foot magnetic tapes
required to hold the same number of blocks. The calculations were
made for 9-channel magnetic tapes at 800 bpi.
No. of magtapes
Required
Disk Device Capacity in Blocks for same capacity
RD10 (Disk) 4000 .139
RM10B (Drum) 2700 .094
RP02 (Disk Pack) 40000 1.39
RP03 (Disk Pack) 80000 2.78
RP04 (Disk Pack) 154280 5.37
RS04 (Disk) 2048 .071
Page 18
APPENDIX
TAPE FORMAT
BACKUP tapes are made up of a series of tape blocks of various types.
All blocks have a uniform length of 544 words. These 544 words are
made up of a 32 word header and a 512 word data area. Even if the
data area is not needed or is partially needed it is fully written.
All undefined or unused words are written with zeroes and ignored on
read. This maximizes the probability of reading old tapes.
The block types are:
BLOCK TYPE SYMBOL DEFINITION
BEGIN T$BEG This is a mandatory block written
at the beginning of the save set.
It identifies the save set, the
device, the system, and the
date/time of writing.
END T$END Same as T$BEG except at the end of
the save set.
DATA T$FIL This is the actual data which has
been saved. It is the only type of
block which is encrypted. It is
self identifying as to the position
within the file, but only contains
part of the full path name of the
file.
UFD T$UFD It contains all the information
necessary to recreate the
directory. (Not written in
interchange mode.)
END OF VOLUME T$EOV A trailer record written as the
last record on tape.
There are several different types of records written. In all the
headers, however, the first seven words are of common meaning to all
record types.
Page 19
They are:
WORD TYPE SYMBOL DEFINITION
RECORD TYPE G$TYPE A number indicating the type of
record. The following values have
been assigned: Label record=1,
Start of Save record=2, End of Save
record=3, file record=4, UFD
record=5, end of volume=6,
comment=7
RECORD NUMBER G$SEQ A sequence number unique to that
record, for that tape. This number
is incremented for each record
written.
RELATIVE TAPE G$RTNM A number indicating the relative
number for this tape within a save
set.
DEPENDENT BITS G$FLAG Various bits dependent on the type
of record involved. Currently, for
all but data records this word is
zero. For file data records, bit 0
is the software end-of-file (this
indicates the last record for this
file). Bit 1 indicates this record
is a repeater of the previous
record (done for error correction's
sake).
1. GF$EOF The flag set if this is
the last tape block for
this disk file. On short
files, it can be set on
the first block of the
file.
2. GF$RPT The flag set if this tape
block is a repeat of the
previous block. This is
set whenever the block is
rewritten because of a
tape write error.
3. GF$NCH The flag set if a
checksum for the tape
block has not been
computed. Bit 2
indicates that the
checksum has not been
done.
Page 20
4. GF$SOF The flag set if this is
the first tape block for
this file. Bit 3
indicates the first tape
record.
G$CHK Contains a checksum of the tape record
unless the GF$NCH bit is set.
G$SIZ The number of words of file data in the
record.
G$LND The number of words to skip before file
data actually begins.
The next five words are reserved for future expansion. The remaining
20 words in the record header vary for each record.
The data portion of a tape record is primarily for storing file data,
but may be used for saving some overhead information. Any non-data
information written in the data area of a tape record is prefaced with
a control word of the form:
LH = type, RH = length in words including this word.
More than one overhead region can appear. In this case, they follow
each other with no intervening space. The currently defined types for
overhead blocks are:
O$NAME Gives the full path identification of
the file without punctuation. The path
components are treated as if the user
gave a quoted representation in "DEC
Integrated Command Language". This
block consists of sub-blocks in the
standard order: device, directories
(top down), file name, extension,
version, generation, sub-blocks
corresponding to missing fields in the
path specification are omitted. Each
sub-block is in the format:
WORD0: LH = type, RH = length in words
including this word.
The rest of the sub-block is the path
field in ASCIZ without leading or
imbedded nulls, terminated by at least
one null. Omitted fields will be
defaulted. In interchange mode, only
the name, extension and version are
written. In interchange restore, only
name, extension and version are used.
Page 21
Sub-block type codes are:
1 = device
2 = name
3 = extension
4 = version
5 = generation
40 = directory (lower directories are
41, 42, ...)
O$FILE A block containing file attributes. The
first section of this block consists of
a fixed length header containing single
word attributes in fixed locations. All
dates and times are in universal
date/time format (i.e., LH = days since
Nov. 17, 1858; RH = fraction of a
day). In interchange mode only the
critical attributes will be written, and
the rest of this block will contain
zeros; so the format will be:
1. A$FHLN -- fixed header length in
words.
2. A$FLGS -- reserved for flags (0 in
interchange mode)
3. A$WRIT -- date/time of last write.
4. A$ALLS -- allocated size in words.
5. A$MODE -- mode of last write.
6. A$LENG -- length in bytes (1B0 if >
2^35-1).
7. A$BSIZ -- byte size (7 or 36).
8. A$VERS -- version identification
(.JBVER format).
The remainder of this block is reserved
for future expansion.
O$DIRT A block reserved for directory
attributes (not written in interchange
mode).
O$SYSN A block containing the system header
line in ASCIZ.
O$SSNM A block containing the save set name in
ASCIZ.
Page 22
Now there will follow a description of each individual word for a
given record type in the T$LBL BLOCK.
WORD TYPE SYMBOL DEFINITION
REEL ID L$RLNM A SIXBIT word defining the reel
name
LABEL date/time L$DATE The date/time of labelling in
DEC-10 universal format (left half
of the word is days since
17-NOV-1859 the right is fractions
of a day)
DESTRUCT DATE L$DSTR The date/time before which the tape
can not be scratched. Before this
time the only valid operation is to
append.
DEVICE ID L$DEV A SIXBIT word defining the physical
name of the magnetic tape drive
used to write the label
FORMAT L$FMT A number indicating the BACKUP
format
VERSION L$BVER A number indicating the BACKUP
version writing this record.
At the start of each save record the following words are found for
T$BEG and T$END blocks:
SYSVER S$SVER A number indicating the system
version
FORMAT S$FMT A number indicating the BACKUP
format
VERSION S$BVER A number indicating the BACKUP
version writing the SAVE set
DATE/TIME S$DATE A number indicating the date and
time of writing in the universal
date/time format.
DEVICE ID S$DEV A sixbit word defining the physical
name of the MTA drive used in
writing the save set.
APR SERIAL S$APR A number indicating the serial
number of the processor which had
directed the writing of this record
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For each UFD record format (T$UFD):
STR NAME D$STR The UFD comes from the structure
defined by this SIXBIT word.
LEVEL NAME D$LVL A number indicating the nesting
level for sub-file
directories: 0=UFD 1-5=SFD level
CHECKSUM NAME D$PCHK A checksum of the O$NAME full path
file name block.
File data record format:
F$PCHK Checksum of the full path file name
block (O$NAME). This is just a
consistency check for consecutive
records of the file.
F$RDW Relative data word of file of first
word on tape.
F$PTH A twelve word block used to store
information suitable for a
restoration of the file. This area
is big enough to hold the entire
path to a TOPS-10 file in a UFD of
up to five characters each in
project and programmer numbers.
The path information will be stored
in the format:
BYTE (7) data type, length in
words, ASCII
where data types are:
001 = device
002 = file name
003 = extension
040+n = nth directory entry