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INPUT/OUTPUT FUNCTIONS
25.2 -- Device Dependent I/O Functions
standard "PROM I/O" error message will
be
displayed
giving
the
status of the error and the sector number that was being
accessed.
Control will then be given
to
the
MOOS
command
interpreter.
If an
error occurs during
the. EREAD function,
the EXIT CONDITIONS described below
appl~
(for C
=
1).
If either
OT
these two functions is to access a diskette
in
a
drive
which
as
not
had the read
functions .DIRSM, . OPEN, . LOAD or
. CHANG,
command),
then
the
diskette
controller
head restored (via
or
via
an
MDOS
Tirmware
must be
entr~
point
is
is
not restored
errors.
invoked to restore t.he
head.
The
RESTOR
described
in
Appendix
D.
IT
the
head
properlYI
it is
possible to receive timeout
The
diskette controller variables below
location
$0020
will be changed
by
these functions.
ENTRY PARAMETERS:
EXIT CONDITIONS:
8
=
The
logical
unit
number.
are ignored.
Bits 2-7
x =
The
address
of
parameter packet.
following Tormat:
a
Tive-byte
IIO
The
packet has the
o
Return
status
1
Physical sector
number
2
to be read
3
Address oT 128
byte
4
sector bUTTer
C
=
0
iT
no
errors
occurred.
The
remainder OT the CC is indeterminate.
The A register is indeterminate.
The X register is unchanged.
The
B
register
contains the return
status returned in the packet ($30).
The
first
byte
of
the
parameter
packet
(Return Status) is
set to $30
( A5.C I I z e r
0 ) .
The
r e ma i n d e
roof
·t
h e
parameter packet is
unchange~:
The
sector
buffer
bytes
read
from
contains the 128
the
specified
Page
25-10
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