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INPUT/OUTPUT FUNCTIONS
25.2
Device Dependent
lID
Functions
25.2.8 Multiple
secto~
output -- . MWRIT, .MEWRT
The . MWRIT and .MEWRT functions are both used to write a
multiple
number
oT
physically
contiguous
sectors
from a
speciried bUTTer to the diskette.
The . MWRIT
function
will
only
return to the calling program if no diskette controller
errors are detected during the
write
attempt.
The
.MEWRT
function,
on
the
other
hand:
~ill
return to the calling
program
whether
an
error
occurred
or
not.
The
.MEWRT
function
will
return
the error status that was detected
by
the diskette controller.
If
an
error
occurred~
the
same
type
of
recover~
procedure
described
in
section
25.2.5 LDREAD • . EREAD)
was
attempted.
In addition,
the same precautions
regarding
the
restoring OT the read head described in that section apply to
the. MWRIT and .MEWRT functions.
ENTRY PARAMETERS:
EXIT
CONDITIONS:
Same as for .MREAD and
.MEREDi
howeve~,
the
sector
bUTTer
must contain the
bytes that are to
be
written
to
the
diskette.
Same
as
ror
.MREAD
and
.MEREDi
howeve~,
the contents of the sector bUTTer are
unchanged
after
returning
to
the
calling program.
25.2.9 Diskette controller entry points
The diskette controller has various
entry
points
that
allow the diskette to be accessed on a physical sector basis;
howeverl
since these entry points are
independent
or
MDOS,
they
are described in a separate section (Appendix
D).
That
appendix also describes some entry points for
accessing
the
line printer on an MOOS-independent basis.
25.3 Device Independent IIO Functions
The
following
sections
describe
functions
which
facilitate
WTiting
software
for
input/output
operations
independent
of
the
physical hardware device.
In addition,
these functions are used to
access
files
on
the
diskette
without having to perTorm physical sector
lID.
Through
the
use
oT
a single parameter table,
the 1/0
Control Block or IOCB, a
common
set
of
functions
can
be
accessed
independently
of. the
I/O dev1ce.
Thus,
the same
function
~ould
be called
ror
writing a record to
a
diskette
file
or
for
writing
a record to a line printer.
The only
difference is in the initial parameterization of the lOeB.
Page
25-13
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