IBM 88553RX, Installation Manual

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Chapter 1. Technical description
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The pop-out panel (Figure 1-15 on page 28) also has a remind button. This
places the front panel system-error LED into remind mode, which means it
flashes briefly every two seconds. By pressing the button, you acknowledge the
failure but indicate that you will not take immediate action. If a new failure occurs,
the system-error LED will turn on again and no longer blink. The system-error
LED remains in the remind mode until one of the following situations occurs:
All known problems are resolved.
The system is restarted.
A new problem occurs, at which time it then is illuminated continuously.
1.10 Extensible Firmware Interface
The Extensible Firmware Interface (EFI) specification describes an interface
between the operating system and platform firmware as shown in Figure 1-16 on
page 30. The interface offers platform-related information to the operating
system as well as boot and runtime service calls that are available to the
operating system and OS loader. Together, this makes a well-defined
environment for booting the operating system and running pre-boot applications,
such as diagnostics, system setup, and driver setup utilities.
In comparison to a BIOS-based, legacy system, the EFI is an additional layer
between the operating system and the firmware. In a legacy system, the OS
loader calls BIOS functions directly. Consequently, to provide a stable boot
environment, changes in the OS loader and the platform firmware must go
hand-in-hand. Figure 1-16 on page 30 shows a conceptual view of the EFI.
Tip: The remind button on the pop-out LPD panel does not function when AC
power has been removed from the system. The button is just used to
acknowledge a system error as described above.