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

ENTER [OPCODE 077]
22.42 ENTER [OPCODE 077]
FUNCTION
Specifies an output file to create, supersede, or update a file.
FILOP. to perform an ENTER for an extended I/O channel.
Use
CALLING SEQUENCE
The ENTER monitor call has two types of argument lists: one using a
four-word argument list and one using an extended argument list. The
extended argument list offers many additional options for ENTERing a
file. For complete information about the argument lists, refer to
Section 11.13.
The calling sequence for the ENTER UUO is:
ENTER channo,addr
error return
skip return
In the call sequence, the program supplies
address of the argument list. Refer
information about the argument list.
SKIP RETURN
the addr,
to Section
which is the
11.13 for more
When you use the short form of the argument block, the monitor returns
a four-word argument block at addr.
Refer to Section 11.13.1 for information about the argument block that
is returned.
When you use the extended argument list, the monitor returns the
information that is listed on Section 11.13.2.
ERROR RETURN
On an error return from ENTER, the monitor returns an error code in
either of the following:
o For the short-form argument block, the error code is stored
in the right half of addr+l of the 4-word argument block
o For the extended-form argument block,
returned in the right half of addr+3.
the error code
",
is
It is possible to LOOKUP/RENAME a file after using an ENTER to specify
the argument list, referring to the same "argument list with subsequent
calls. Note, however, that on an error return from the ENTER, the
error code overwrites the high-order three bits of the creation date
and the entire access date. Because most programs recover from these
errors by either aborting or by reinitializing the entire argument
block, this overwriting of data normally does not cause any problems.
However, a program may attempt to recover from an error by fixing only
the incorrect portion of the argument block and then reexecuting the
monitor call. These programs should always initialize the contents of
these locations before reexecuting the ENTER monitor call.
Error codes are restricted to a maximum of 15 bits to eliminate
problems when recovering from an error in a file with a zero creation
date. The error codes are described in Section 11.14.
22-122