IBM Personal System/2 50 User Manual

Real-Time
Clock/Complementary
Metal-Oxide
Semiconductor
RAM
The
real-time
clock/complementary
metal-oxide
semiconductor
RAM
(RT/CMOS)
chip
contains
the
real-time
clock
and
64
bytes
of
CMOS
RAM.
The
internal
clock
circuitry
uses
14
bytes
of
this
memory,
and
the
rest
is
allocated
to
configuration
and
system
status
information.
A
6-Vde
lithium
battery
maintains
voltage
to
the
RT/CMOS
RAM
when
the
power
supply
is
not
in
operation.
The
system
cover
can
be
locked
to
prevent
battery
removal
and
loss
of
password
and
configuration
information.
The
following
figure
shows
the
RT/CMOS
RAM
bytes
and
their
addresses.
Address
(Hex)
RT/CMOS
RAM
Bytes
000
-
OOD
Real-Time
Clock
Bytes
OOE
Diagnostic
Status
Byte
OOF
Shutdown
Status
Byte
010
Diskette
Drive
Type
Byte
011
First
Fixed
Disk
Drive
Type
Byte
012
Second
Fixed
Disk
Drive
Type
Byte
013
Reserved
014
Equipment
Byte
015
-
016
Low
and
High
Base
Memory
Bytes
017
-
018
Low
and
High
Expansion
Memory
Bytes
019
-
031
Reserved
032
-
033
Configuration
CRC
Bytes
034
Reserved
035
-
036
Low
and
High
Useable
Memory
Bytes
037
Date
Century
Byte
038
-
O3F
Reserved
Figure
3-8.
RTICMOS
RAM
Address
Map
3-12
Model
50
System
Board
—
October
1990

IBM Personal System/2 50 Specifications

General

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