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NEC CP/M-86 - Page 63

NEC CP/M-86
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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.
4-29

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