Technical data

Functional Description
Battery Backed Real-Time Clock
2-25
Battery Backed Real-Time Clock
The Model 743 uses a battery backed read-time clock. This section provides safety infor-
mation for handling lithium batteries. This section also provides information on the timers
used in the Model 743.
WARNING: Lithium batteries can explode if mistreated. Do not
put lithium batteries in fires or try to recharge or
disassemble them. Replace lithium batteries only with
Matsushita Electric BR-1616 three-volt lithium
batteries (HP part number 1420-0525)! Use of any
other battery can cause fire or explosion.
The battery-backed clock is implemented in the I/O controller ASIC. Once power is
applied to the system board, the battery-backed clock time is read by the operating system
only during system initialization. Once the operating system is booted, real time is kept
using the timer built into the CPU. The battery-backed real-time clock is updated by the
operating system only when the user explicitly requests it. Table 2-19 lists the Real-time
clock specification.
Table 2-19 Real-Time Clock Specifications
Resolution:
1 second
Battery Type:
Lithium
Battery Life:
Power off: 6 months
Power on, 10 years