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Compaq Professional Workstation AP500 Maintenance and Service Guide
FailSafe Boot Block ROM
The FailSafe Boot Block ROM enables system recovery in the unlikely event of a system ROM
upgrade failure, for example, if a power failure occurs during a system ROM upgrade. The Boot
Block is a flash-protected section of the ROM that checks to validate the system ROM each time
power to the system is turned on.
■ If the system ROM is valid, the system starts normally.
■ If the system ROM fails the validation check, the FailSafe Boot Block ROM provides
enough support to start the system from a ROMPaq diskette, which programs the system
ROM with a valid image.
IMPORTANT: The workstation ships with the Diskette Boot feature enabled. If the diskette
drive is disabled, the FailSafe Boot Block ROM will override the disabled component to
accommodate a system ROM recovery in the event a system ROM failure occurs.
Because there is no video or hard drive support from the Boot Block ROM, the keyboard lights
communicate information. When the Boot Block detects an invalid system ROM, the system
sounds a series of beeps (one long and three short) and flashes the three keyboard lights.
To recover the system after hearing the FailSafe Boot Block beeps:
1. Remove any diskettes from the diskette drive and turn off the power.
2. Insert a user ROMPaq diskette into the diskette drive.
3. Turn on power to the system.
If a Setup Password has been established, the Caps Lock light will turn on.
4. Enter the Setup Password.
When the system successfully starts from the diskette and reprograms the ROM, the
following three keyboard lights will turn on.
1 2 3
Figure 4-1. Identifying keyboard lights