Basic Disk Operating System (BDOS) Functions
4-18
to
write sequentially from
the
beginning
of
the
file. Register
AL
is
set
to
OOH
if
the
write
operation
is
successful.
An
unsuccessful write returns one
of
the
following
values in AL.
01
No
available directory space -
The
write
command
attempted
to
create
a new extent
that
required a new directory entry
and
no
available
directory entries existed
on
the selected disk drive.
02
No
available
data
block -
The
write
command
attempted
to
allocate a
new
data
block
to
the file
and
no
unallocated
data
blocks existed
on
the
selected disk drive.
MAKE
FILE
ENTRY
CL: 16H
DX:
FCB
Offset
RETURN
FUNCTION
22
AL:
Return
Code
MAKE
FILE
The
Make
File
function
is
similar
to
the
Open
File function except
that
the
FCB
must
name
a file which does
not
exist in the currently referenced disk
directory
(Le.,
the
one
named
explicitly by a
non-zero
"dr" code,
or
the
default disk
if"dr"
is zero).
The
BDOS
creates the file
and
initializes
both
the
directory
and
main
memory
value
to
an
empty
file.
The
programmer
must
ensure
that
no
duplicate file
names
occur.
(A
preceding
delete
operation
is sufficient
if
there is
any
possibility
of
duplication.)
Register
AL
returns
0,
1,
2,
or
3
if
the
operation
was successful
and
OFFH (255
decimal)
if
no
more
directory space is available. Since the
Make
File
function
activates the
FCB,
a subsequent
Open
File function is
not
necessary.
RENAME
FILE
ENTRY
CL: 17H
DX:
FCB
Offset
RETURN
FUNCTION
23
AL:
Return
Code
RENAME
FILE
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