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Basic Disk Operating System (BDOS) Functions
Table 4-5 Function 34 (Write Random) Error Codes
CODE
01
02
03
04
05
06
MEANING
(not returned by the Random Write command)
No a vaiia ble data block - The Write Random command
attempts to allocate a new data block to the file and no
unallocated data blocks exist on the selected disk drive.
Cannot close current extent - The BOOS cannot close
the current extent prior to moving to the new extent
containing the record specified by bytes rO, r 1 of the FCB.
This error can be caused by an overwritten FCB or a write
random operation on an FCB that has not been opened.
(not returned by the Random Write command)
No available directory space -
The write command
attempts to create a new extent that requires a new
directory entry and no available directory entries exist on
the selected disk drive.
Random record number out of range -
Byte r2 of the
FCB is non-zero.
The virtual size of a file corresponds to the physical size only when the file is written
sequentially. If a file is created in random mode and "holes" exist in the allocation,
then the file may in fact contain fewer records than the size indicates. For example,
if a single record with record number 65535 (CP/M's maximum record number) is
written to a file using the Write Random function, then the virtual size of the file is
65536 records, although only one block of data is actually allocated.
To append data to the end of an existing file, call function 35 to set the random
record position to the end of file. Then, perform a sequence of random writes
starting at the preset record address.
4-27
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