TOPS-10 Monitor Calls Manual Volume 2 AA-K039D ... - Trailing-Edge

FILOP. [CALLI 155]
35 . FOFXO Performs an OUT monitor call, using extended
addressing and dump-mode I/O. The argument list
is:
addr:
XWD
addr1
addr2
channo, .FOFXO
In the argument list:
o
channo is the channel number on which data is
written to the opened file.
o
addr1 is the
Conunand list
.FOFXI.
address
format
of
is
the conunand list.
described above in
o addr2 is the (optional) address of a word
containing the block number of the file to
perform a USETO to before writing.
The I/O status bits are returned in the ac.
22.48.3 Simu1taneous Fi1e Access with FILOP. UUO
Multiple channels of a single job and/or multiple jobs can update a
file simultaneously using FILOP. The monitor imposes no restrictions
or interlocks when a file is being simultaneously updated. Therefore,
users must ensure that separate jobs do not update the same block of
the same file at the same time. The ENQ/DEQ Facility (refer to
Chapter 8) may be used to ensure that such interference does not
occur, but the monitor does not require its use when simultaneously
updating a file.
To update a file simultaneously, your program performs a
FILOP. monitor call using function code 5 (.FOMAU). A file can be
updated in thi~ manner when the file is idle, when it is being read,
or when it 1S being updated by other jobs. A file cannot be
simultaneously updated if the file is in single-access update mode;
that is, when a LOOKUP and an ENTER have been performed or a
FILOP. has been performed with Function code 4 (.FOSAU) or Function 6
(. FOAPP) .
Note that although an extended LOOKUP/ENTER/RENAME block can be
specified by the FILOP. monitor call, your program cannot change the
file attributes of a simultaneously updated file. The FILOP. monitor
call uses the first four words of the extended argument list.
In order to prevent excessive monitor overhead, files that are to be
simultaneously updated should be pre-allocated into contiguous blocks,
if possible. This will prevent the creation of inefficient retrieval
pointers, and will lessen the chance that extended RIBs will be
created.
22-152