IBM Personal System/2 50 User Manual

Status
Register
C
(Hex
00Cc)
Bit Function
7
Interrupt
Request
Flag
6
Periodic
Interrupt
Flag
§
Alarm
interrupt
Flag
4
Update-Ended
Interrupt
Flag
3-90 Reserved
Figure
3-14.
Status
Register
C
Note:
Interrupts
are
enabled
by
bits
6,
5,
and
4
in
Status
Register
B.
Bit7
This
bit
is
used
in
conjunction
with
bits
6,
5,
and
4.
When
set
to
1,
this
bit
indicates
that
an
interrupt
has
occurred;
bits
6,
5,
and
4
indicate
the
type
of
interrupt.
Bité6
When
set
to
1,
this
bit
indicates
that
a
periodic
interrupt
occurred.
Bits
When
set
to
1,
this
bit
indicates
that
an
alarm
interrupt
occurred.
Bit
4
When
set
to
1,
this
bit
indicates
that
an
update-ended
interrupt occurred.
Bits3-0 Reserved.
Status
Register
D
(Hex
00D)
Bit Function
7 Valid RAM
6-0 Reserved
Figure
3-15.
Status
Register
D
Bit
7
This
read-only
bit
monitors
the
power-sense
pin.
A
low
state
of
this
pin
indicates
a
loss
of
power
to
the
real-time
clock
(dead
battery).
When
set
to
1,
this
bit
indicates
that
the
real-time
clock
has
power.
When
set
to
0,
it
indicates
that
the
real-time
clock
has
lost
power.
Bits6-0 Reserved.
3-18
Model
50
System
Board
—
October
1990

IBM Personal System/2 50 Specifications

General

Brand	IBM
Model	Personal System/2 50
Category	Desktop
Language	English