User Manual
BCM1250/BCM1125/BCM1125H
10/21/02
B r o a d c o m C o r p o r a t i o n
Document
1250_1125-UM100CB-R
Section 3: System Overview
Page
35
The memory controller supports up to 1 GB of memory in a system that is restricted to 32-bit physical
addresses, and up to 4 GB ( 2 GB on BCM1125/H) using 512 Mb technology DRAMs (up to 8 GB when 1Gb
technology SDRAMs are available, and with an option to double the size at the cost of speed with an external
decoder) on systems with a full 40-bit address. The address map includes 512 MB for mapping PCI and
HyperTransport memory mapped peripherals that use 32-bit addressing, and an alias for this space that will
byte swap accesses when the system is in big endian mode.
Accesses to Reserved or Unused regions will result in UNPREDICTABLE behavior. Writes will be discarded.
Figure 9: Memory Map
System Control and Debug
First SDRAM Region
Boot ROM
Internal Devices
Reserved
PCI/HT Config
01_0000_0000
00_A000_0000
00_0000_0000
SDRAM Expansion
Maps to
00_D800_0000
-
00_DFFF_FFFF
With "Match Bit" Endian Policy
PCI/HT I/O Space
HT/PCI Special
L2 Direct Access
Fourth SDRAM Region
Third SDRAM Region
Second SDRAM Region
PCI/LDT Memory Space
Match Bit Lane Endian Policy
00_1000_0000
00_1006_0000
00_1009_0000
Generic Bus Devices
(Default for IO_CS0)
00_1FC0_0000
00_2000_0000
00_4000_0000
00_6000_0000
00_8000_0000
00_9000_0000
PCI/LDT Memory Space
00_F800_0000
00_E000_0000
00_DE00_0000
00_DC00_0000
00_D800_0000
00_D000_0000
00_C000_0000
Match Byte Lane Endian Policy
Reserved
HT Devices
Reserved
80_0000_0000
F8_0000_0000
FF_FFFF_FFFF
PCI Full Access
FA_0000_0000
Not on BCM1125