IBM Personal System/2 65 SX User Manual

The
Card-Selected
Feedback
register
is
a
read-only
register
at
address
hex
0091.
It
allows
programs
to
monitor
-CD
SFDBK
and
determine
if
the
video
subsystem,
system-board
I/O,
or
an
adapter
is
addressed
and
functioning.
Bit Function
7-1 Reserved
0
Card-Selected
Feedback
Figure
2-2.
Card-Selected
Feedback
Register
(Hex
0091)
Bilis 7-1 Reserved.
BitO
This
bit
is
set
to
1
whenever
-CD
SFDBK
was
active
ona
previous
cycle
or
whenever
the
system-board
I/O
functions
(diskette
drive,
serial,
or
parallel
interfaces)
are
accessed
by
an
I/O
cycle.
Reading
this
register
resets
the
bit
to
0.
System-Board
Setup
The
integrated
I/O
functions
on
the
system
board
use
POS
information
during
setup.
POS
treats
the
diskette-drive
controller,
serial
port,
and
parallel
port
as
a
single
device.
The
video
subsystem
also
is
an
integrated
part
of
the
system
board,
but
POS
treats
it
as
a
separate
device.
The
System-Board
Enable/Setup
register
is
used
to
place
the
system
board
or
the
video
subsystem
in
the
setup
mode.
2-6
Model
65
POS
—
October
1990

IBM Personal System/2 65 SX Specifications

General

Brand	IBM
Model	Personal System/2 65 SX
Category	Desktop
Language	English