IBM Personal System/2 60 User Manual

Bits 3-0
These bits allow the selection of a divider output
frequency.
The
system
initializes
the
rate
selection
bits
to
a
binary
0110,
which
selects
a
1.024
kHz
square-wave
output
frequency
and
a
976.562-microsecond
periodic
interrupt rate.
Status Register B (Hex 00B)
Function
Set
Periodic interrupt Enable
Alarm Interrupt Enable
Update-Ended Interrupt Enabled
Square Wave Enabled
Date Mode
24-Hour Mode
Daylight Savings Enabled
O]{jN0OR
NON
Figure 3-11. Status Register B
Bit 7
Bité6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
When set to 0, this bit updates the cycle, normally by
advancing
the
counts
at
a
rate
of
one
per
second.
When
set to 1, this bit immediately ends any update cycle in
progress,
and
the
program
can
initialize
the
14
time
bytes
without
any
further
updates
occurring
until
this
bit
is
set
to
0.
This
bit
is
a
read/write
bit
that
allows
an
interrupt
to
occur
at
a
rate
specified
by
the
rate
and
divider
bits
in
Status
Register
A.
When
set
to
1,
this
bit
enables
the
interrupt.
The
system
initializes
this
bit
to
0.
When
set
to
1,
this
bit
enables
the
alarm
interrupt.
The
system
initializes
this
bit
to
0.
When
set
to
1,
this
bit
enables
the
update-ended
interrupt.
The
system
initializes
this
bit to
0.
When
set
to
1,
this
bit
enables
the
square-wave
frequency
as
Set
by
the
rate-selection
bits
in
Status
Register
A.
The
system
initializes
this
bit
to
0.
This
bit
indicates
if
the
time-and-date
calendar
updates
use
binary
or
binary-coded-decimal!
(BCD)
formats.
When
set
to
1,
this
bit
indicates
a
binary
format.
The
system
initializes
this
bit
to
0.
This
bit
establishes
if
the
hours
byte
is
in
the
24-hour
or
12-hour
mode.
When
set
to
1,
this
bit
indicates
the
24-hour
mode.
The
system
initializes
this
bit
to
1.
3-14 Model 60 System Board — October 1990

IBM Personal System/2 60 Specifications

General

Brand	IBM
Model	Personal System/2 60
Category	Desktop
Language	English