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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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