Intel BONANZA S478 I875 ATX DDR BLKD875PBZLK User Manual

 

  

49 

2.1

 

Introduction.................................................................................................................49

 

2.2

 

Memory Resources ....................................................................................................49

 

2.3

 

DMA Channels ...........................................................................................................51

 

2.4

 

Fixed I/O Map.............................................................................................................52

 

2.5

 

PCI Configuration Space Map ....................................................................................53

 

2.6

 

Interrupts ....................................................................................................................54

 

2.7

 

PCI Interrupt Routing Map ..........................................................................................55

 

2.8

 

Connectors .................................................................................................................57

 

2.9

 

Jumper Blocks ............................................................................................................72

 

2.10

 

Mechanical Considerations.........................................................................................74

 

2.11

 

Electrical Considerations ............................................................................................77

 

2.12

 

Thermal Considerations..............................................................................................79

 

2.13

 

Reliability ....................................................................................................................81

 

2.14

 

Environmental ............................................................................................................81

 

Sections 2.2 - 2.6 contain several standalone tables.  Table 12 describes the system memory map, 
Table 13 lists the DMA channels, Table 14 shows the fixed I/O map, Table 15 defines the PCI 
configuration space map, and Table 16 describes the interrupts.  The remaining sections in this 
chapter are introduced by text found with their respective section headings. 

The D875PBZ 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 15 shows a schematic of the system memory map.  All