33
2
Technical Reference
2.1
Memory Map
2.1.1
Addressable Memory
The board utilizes 4 GB of addressable system memory. Typically the address space
that is allocated for PCI Conventional bus add-in cards, PCI Express configuration
space, BIOS (SPI Flash), and chipset overhead resides above the top of DRAM (total
system memory). On a system that has 4 GB of system memory installed, it is not
possible to use all of the installed memory due to system address space being
allocated for other system critical functions. These functions include the following:
•
BIOS/ SPI Flash (4 MB)
•
Local APIC (19 MB)
•
Direct Media Interface (40 MB)
•
Front side bus interrupts (17 MB)
•
Internal graphics address registers
•
Memory-mapped I/O that is dynamically allocated for PCI Conventional add-in
cards
