82378ZB Datasheet, PDF (40/137 Pages) Intel Corporation – SYSTEM I/O APIC(SIO.A) AND

82378ZB (SIO) AND 82379AB (SIO.A)
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3.1.11. MCSBOH—MEMCS# BOTTOM OF HOLE REGISTER
Address Offset:
Default value:
Attribute:
45h
10h
Read/Write
This register defines the bottom of the MEMCS# hole. MEMCS# is not generated for accesses to addresses
within the hole defined by this register and the MCSTOH Register. The hole is defined by the following equation:
TOH ≥ address ≥ BOH. TOH is the top of the MEMCS# hole defined by the MCSTOH Register and BOH is the
bottom of the MEMCS# hole defined by this register. For example, to program the BOH at
1 Mbyte, the value of 10h should be written to this register. To program the BOH at 2 Mbytes + 64 Kbytes this
register should be programmed to 21h. To program the BOH at 8 Mbytes, this register should be programmed to
80h.
When the TOH < BOH the hole is effectively disabled. It is the responsibility of the programmer to guarantee that
the BOH is at or above 1 Mbyte. AD[31:24] must be 0's for the hole, meaning the hole is restricted to be under
the 16-Mbyte boundary. The default value for the BOH and TOH effectively disables the hole.
Bit
Description
7:0 Bottom Of Memory Hole: Bits[7:0] correspond to address lines AD[23:16], respectively.
3.1.12. MCSTOH—MEMCS# TOP OF HOLE REGISTER
Address Offset:
Default value:
Attribute:
46h
0Fh
Read/Write
This register defines the top of the MEMCS# hole. MEMCS# is not generated for accesses to addresses within
the hole defined by this register and the MCSBOH Register. The hole is defined by the following equation: TOH
≥ address ≥ BOH. TOH is the top of the MEMCS# hole defined by this register and BOH is the bottom of the
MEMCS# hole defined by the MCSBOH Register. For example, to program the TOH at
1 Mbyte + 64 Kbytes, this register should be programmed to 10h. To program the TOH at 2 Mbytes +
128 Kbytes, this register should be programmed to 21h. To program the TOH at 12 Mbytes, this register should
be programmed to BFh.
When the TOH < BOH the hole is effectively disabled. It is the responsibility of the programmer to guarantee that
the TOH is above 1 Mbyte. AD[31:24] must be 0's for the hole, meaning the hole is restricted to be under the 16
Mbyte boundary. The default value for the BOH and TOH effectively disables the hole.
Bit
Description
7:0 Top Of Memory Hole: Bits[7:0] correspond to address lines AD[23:16], respectively.
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