Intel BLKDG41TX, Technical Product Specification, Page: 39 / 90

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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 Conventional PCI 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 (16 Mbits)
• Local APIC (19 MB)
• Direct Media Interface (40 MB)
• Front side bus interrupts (17 MB)
• PCI Express configuration space (256 MB)
• GMCH base address registers, internal graphics ranges, PCI Express ports (up to
512 MB)
• Memory-mapped I/O that is dynamically allocated for Conventional PCI bus and
PCI Express add-in cards
• Base graphics memory support (1 MB or 8 MB)
NOTE
System resources and hardware (such as Conventional PCI and PCI Express*) require
physical memory address locations that can reduce available addressable system
memory. This could result in a reduction of as much as 1 GB or more of physical
addressable memory being available to the operating system and applications,
depending on the system configuration and operating system.