Technical Reference; Introduction; Memory Resources; Addressable Memory - Intel BLKD865PERL Technical Product Specification

2 Technical Reference

What This Chapter Contains
2.1

Introduction.................................................................................................................51

2.2

Memory Resources ....................................................................................................51

2.3 DMA Channels ...........................................................................................................53
2.4 Fixed I/O Map.............................................................................................................54
2.5 PCI Configuration Space Map ....................................................................................55
2.6 Interrupts ....................................................................................................................56
2.7 PCI Interrupt Routing Map ..........................................................................................57
2.8 Connectors .................................................................................................................59
2.9 Jumper Blocks............................................................................................................74
2.10 Mechanical Considerations.........................................................................................76
2.11 Electrical Considerations ............................................................................................78
2.12 Thermal Considerations..............................................................................................80
2.13 Reliability ....................................................................................................................82
2.14 Environmental ............................................................................................................82
2.1 Introduction
Sections 2.2 - 2.6 contain several standalone tables. Table 13 describes the system memory map,
Table 14 lists the DMA channels, Table 15 shows the fixed I/O map, Table 16 defines the PCI
configuration space map, and Table 17 describes the interrupts. The remaining sections in this
chapter are introduced by text found with their respective section headings.
2.2 Memory Resources

2.2.1 Addressable Memory

The D865PERL utilizes 4 GB of addressable system memory. Typically the address space that is
allocated for PCI add-in cards, AGP aperture, BIOS (firmware hub), 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:
•
Memory-mapped I/O that is dynamically allocated for PCI and AGP cards
•
AGP aperture
•
APIC and chipset overhead (approximately 18 MB)
•
BIOS/firmware hub (approximately 2 MB)
The amount of installed memory that can be used will vary based on add-in cards and BIOS
settings. For example, if the PCI cards are requesting 200 MB of system memory and the AGP
aperture is set to 256 MB in the BIOS Setup program, there will be approximately 3.54 GB of
memory that can be accessed. Figure 18 shows a schematic of the system memory map. All
installed system memory can be used when there is no overlap of system addresses. For example,
all of the system address space can be utilized on a system that has 2 GB of installed system
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