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Basic Disk Operating System (BDOS) Functions
RESET DRIVE
ENTRY
CL: 25H
DX: Drive
Vector
RETURN
FUNCTION 37
AL: OOH
RESET DRIVE
The Reset Drive function programmatically restores specified drives to the reset
state. A reset drive is not logged in and is in read/write status. The parameter in
register DX is a 16-bit vector of drives to be reset, where the least significant bit
corresponds to the first drive, A, and the high order bit corresponds to the sixteenth
drive, P. (The APC is configured for drives A - H only.) Bit values of "1" indicate
that the specified drive is to be reset. Register AL returns
OOH
when the operation is
complete.
WRITE RANDOM WITH ZERO FILL
ENTRY
CL: 28H
DX: FCB
Offset
FUNCTION 40
WRITE RANDOM
WITH ZERO FILL
RETURN
AL: Return Code
The Write Random With Zero Fill function writes data to disk from the current
DMA address (like function 34) and also initializes a previously unallocated data
block to zero-filled records before the block is written. If this function has been used
to create a file, records accessed by a read random operation that contain all zeros
identify unwritten random records. Unwritten random records in allocated data
blocks of files created using the Write Random function contain uninitialized data.
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