Atari 400 Technical Reference Manual page 124

GETSTAT
This
entr~
is called in response to a GET STATUS command to CIO.
The handler is expected to return four bytes of status to memory
or return an error status in the V register.
At handler entr~, the following parameters can be of interest:
x
= index to originating IOCB.
V
=
$92 (status
=
function not
implemented by handler).
ICDNOZ [0021J
=
device number (1-4, for multiple device handlers).
ICBALZ/ICBAHZ [0024/0025J
=
address of
device/filename specification.
ICAX1Z/ICAX2Z
[002A/002BJ
=
device-specific information.
The handler gets device status information from the device
controller and puts the status bytes in DVSTAT [02EAJ through
DVSTAT+3, and
finall~
returns to CIO with the operation status
in register V.
The IOCB need not be opened nor closed in order for ~ou
to re~uest CIO to perform a GET STATUS operation; the handler
must check where there are restrictions. See Section 5 for a
discussion of the CIO actions involved with a GET STATUS
operation using both open and closed IOCB's, and note the impact
of this operation on the use of the buffer address parameter.
SPECIAL
This handler
entr~
is used to support all functions not handled
by the other entr~ points, such as diskette file RENAME, display
DR AW, etc. Sp e c i f i call ~ , i f the I OC B comma n d by t e va 1 u e i s
greater than $00, then CIa will use the SPECIAL entry point. The
handler must interrogate the command byte to determine if the
re~uested operation is supported.
At handler entry, the following parameters can be of interest:
x =
index to originating IOCB.
Y
=
$92 (status
=
function not implemented by handler).
ICDNOZ [0021J
=
device number ( 1-4, for multiple device
hand lers).
ICCOMZ [0022J
=
command byte.
ICBALZ/ICBALH [0024/0025J
=
buffer address.
ICBLLZ/ICBLHZ [0028/0029J
=
buffer length.
ICAX1Z/ICAX2Z [002A/002BJ
=
device-specific in for ma t ion.
OPERATING SYSTEM C016555 -- Section 9
139