82C836 Datasheet, PDF (129/205 Pages) List of Unclassifed Manufacturers – Single-Chip 386sx AT

82C386 CHIPSet Data Sheet
Configuration Registers s
Port 209H (0r 219H) accesses bits 23 and 22 of the address of the 16KB target page
mapped into the selected page window of the 64KB remappable address range. The page
register accessed by this port is selected by port 20AH (or 21AH).
Table 10-21. Port 209H----Page Enable
Bit
Name
7
Page Enable
6-2
----
1
----
0
----
Description
‘‘Page disable ’’ means that the page window in the 64KB remappable address
range is not remapped but is treated as ordinary non-EMS memory.
1 = page Enable
0 = page Disable.
Reserved.
A23 of target page address
A22 of target page address
Table 10-22. Port 20AH----EMS Page Select
Bit
Name
Description
7
Auto-Increment
Enables auto-incrementing of the page register selection index (bits 1-0 in
this register) whenever port 208H (or 218H) is read or written. Incrementing
does not occur on access to port 209H (or 219H). 16-bit I/O may be used to
read or write both ports 208H and 209H (or 218H/219H) simultaneously,
with or without auto-increment.
1 = Enable auto-incrementing
0 = Disable auto-incrementing
6
Page Frame
Determines whether the 64KB remappable address range (page frame)
Base Address
begins at 0D0000H or 0E0000H.
0 = 0D0000H (default)
1 = 0E0000H
5-2
----
Reserved.
1-0
Index
Selects one of the four EMS Page Registers for access via ports 208H and
209H (or 218H and 219H). Can be programmed for automatic incrementing
via bit 7 above. Page registers are numbered in order from 00 through 11
(binary), and the associated page window addresses in the 64KB remappable
address range follow in ascending order.
Chips and Technologies, Inc.
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