CL-PD6833
PCI-to-CardBus Host Adapter
9.2
Memory Window Mapping Registers
The following information about memory window mapping is important:
●
The Memory Window Mapping registers determine where in the PCI memory space and PC Card memory
space accesses occur. There are five memory windows that can be used independently.
●
●
The memory windows are enabled and disabled using the Mapping Enable register.
To specify where in the PCI space a memory window is mapped, start and end addresses are specified. A
memory window is selected whenever the appropriate Memory Map Enable bit is set and the following con-
ditions are true:
— The PCI address is greater than or equal to the appropriate System Memory Map Start Address
register (see Section 9.2.1).
— The PCI address is less than or equal to the appropriate System Memory Map End Address register
(see Section 9.2.3).
— The System Memory Map Upper Address register is equal to the upper PCI address.
●
Start and end addresses are specified with PCI Address bits 31:12.This sets the minimum size of a memory
window to 4 Kbytes. Memory windows are specified in the PCI memory address space.
●
To ensure proper operation, none of the memory windows can overlap in the PCI address space.
9.2.1
System Memory Map 0–4 Start Address Low
Register Name: System Memory Map 0–4 Start Address Low
Register Per: socket
Register Compatibility Type: 365
I/O Index: 10h, 18h, 20h, 28h, 30h
Memory Offset: 810h, 818h, 820h, 828h, 830h
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Start Address 19:12
R/W:00000000
There are five separate System Memory Map Start Address Low registers, each with identical fields.
These registers are located at the following indexes:
Index (Socket A)
Register
10h
18h
20h
28h
30h
System Memory Map 0 Start Address Low
System Memory Map 1 Start Address Low
System Memory Map 2 Start Address Low
System Memory Map 3 Start Address Low
System Memory Map 4 Start Address Low
Bits 7:0 — Start Address 19:12
This register contains the least-significant byte of the address that specifies where in the memory
space the corresponding memory map begins. Memory accesses that are equal to or above this
address and equal to or below the corresponding System Memory Map End Address are mapped
into the memory space of the corresponding PC Card.
The most-significant four bits are located in the System Memory Map 0–4 Start Address High
register.
110
June 1998
WINDOW MAPPING REGISTERS
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