CL-PD6710/’22
ISA–to–PC-Card Host Adapters
8. MEMORY WINDOW MAPPING REGISTERS
The following information about the memory map windows is important:
● The memory window mapping registers determine where in the ISA memory space and PC Card memory
space accesses will occur. There are five memory windows that can be used independently.
● The memory windows are enabled and disabled using the Mapping Enable register (see page 47).
● To specify where in the ISA space a memory window is mapped, start and end addresses are specified. A
memory window is selected whenever the appropriate Memory Map Enable bit (see page 47) is set, and
when the ISA address is greater than or equal to the appropriate System Memory Map Start Address reg-
ister (see page 53) and the ISA address is less than or equal to the appropriate System Memory Map End
Address register (see page 54).
● Start and end addresses are specified with ISA Address bits 23:12.This sets the minimum size of a memory
window to 4K bytes. Memory windows are specified in the ISA address from 64 Kbytes to 16 Mbytes
(0010000h–FFFFFFh). Note that no memory window can be mapped in the first 64 Kbytes of the ISA address
space.
● To ensure proper operation, none of the windows can overlap in the ISA address space.
8.1 System Memory Map 0–4 Start Address Low
Register Name: System Memory Map 0–4 Start Address Low
Index: 10h, 18h, 20h, 28h, 30h
Register Per: socket
Register Compatibility Type: 365
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Start Address 19:12
RW: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
System Memory Map Start Address Low
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 will begin. Memory accesses that are equal or above this
address and equal or below the corresponding System Memory Map End Address will be 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 (see page 54).
May 1997
53
PRELIMINARY DATA SHEET v3.1
MEMORY WINDOW MAPPING REGISTERS
CIRRUS [ CIRRUS LOGIC ]
