Intel STL2 - Manual (Page 25)

STL2 Server Board TPS STL2 Server Board Architecture Overview
Revision 1.0 2-17
2.5.2 BIOS Flash
The STL2 baseboard incorporates an Intel
®
5V FlashFile™ 28F008SA Flash Memory
component. The 28F008SA is a high-performance 8 Mbit memory that is organized as 1 MB of
8 bits each. There are 16 64-KB blocks.
The 8-bit flash memory provides 1024K x 8 of BIOS and nonvolatile storage space. The flash
device is directly addressed as 8-bit ISA memory.
For more information, see the 5 Volt
FlashFile™ Memory (28F008SA x8) Datasheet.
2.5.3 External Device Connectors
The external I/O connectors provide support for a PS/2 compatible mouse and keyboard, an
SVGA monitor, two serial port connectors, a parallel port connector, a LAN port, and two USB
connections.
2.6 Interrupt Routing
The STL2 server board interrupt architecture implements two I/O APICs and two PICs through
the use of the integrated components in the IB6566 South Bridge component. The STL2
server board interrupt architecture allows first and second PCI interrupts to be mapped to
compatible interrupt through the PCI Interrupt Address Index Register (I/O Address 0C00h) in
the IB6566 South Bridge.
The STL2 server board supports three interrupt modes:
•
PIC Mode
•
Virtual Wire Mode
• Symmetric Mode
The IB6566 South Bridge uses integrated logic to map 16 PCI interrupts to EISA/ISA. In
default or Extended APIC configurations, each PCI interrupt can be independently routed to
one of the 11 EISA interrupts. The interrupt mapping logic for PCI interrupts is disabled when
the make bit in the corresponding I/O APIC redirection table entry is disabled (clear). This
interrupt routing mechanism allows a clean transition from PIC mode to an APIC during
operating system boot.
2.6.1 Default I/O APIC
The IB6566 South Bridge integrates a 16-entry I/O APIC which is used to distribute 16 PCI
interrupts.
2.6.2 Extended I/O APIC
An additional 16-entry I/O APIC is integrated in the IB6566 South Bridge to distribute EISA/ISA
interrupts. This additional I/O APIC is enabled only when the IB6566 South Bridge is
configured to the Extended APIC configuration.