PC87413 datasheet(84/257 Pages) NSC

84 / 257 page

3.0 Device Architecture and Configuration (Continued)

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Revision1.2

3.15.12 X-Bus Memory Configuration Register 2 (XMEMCNF2)

This register is reset by hardware to 00h.

Power Well:VSB

Location:Index F8h

Type:

Varies per bit

Bit

76543210

Name

LOCKMMP

Reserved

SEL2UDM

SEL2BIOS

BIOSIZE

Reset

00000000

Bit

Description

LOCKMMP (Lock Memory Address Map). When set to 1, this bit locks the conﬁguration of registers

XMEMCNF1, XMEMCNF2, XMEMBAH, XMEMBAL and XMEMSIZE by disabling writing to all their bits

(including to the LOCKMAP bit itself). Once set, this bit can be cleared either by VDD Power-Up reset (or

Hardware reset) or by VSB Power-Up reset, according to the VSBLOCK bit in the ACBLKCTL register (see

Section 6.3.4 on page 128). In addition, this bit is cleared by setting the UNLOCKX bit in the ACBLKCTL register

(PC87417).

0: R/W bits are enabled for write (default)

1: All bits are RO

6-5

Reserved.

SEL2UDM (Dual User-Defined Memory Select Enable). Enables the PC8741x device to control two memory

devices for data storage. The second zone (MEM Zone 1) is mapped on top of the ﬁrst zone (MEM Zone 0).

Both zones are the same size. The base address of MEM Zone 0 is speciﬁed by the XMEMBAH and XMEMBAL

registers. The size of both memory zones is speciﬁed by the XMEMSIZE register. The base address of MEM

Zone 1 is: (Base Address Memory Zone) + (Size Memory Zone).

0: Disabled - Use only MEM Zone 0, if enabled (default)

1: Enabled - If the user-defined memory is enabled, use both MEM Zone 0 and MEM Zone 1

SEL2BIOS (Dual BIOS Select Enable). Enables the PC8741x device to control two ﬂash devices for BIOS

storage. The ﬁrst device (BIOS Zone 0) is used for legacy and the upper 386 zone. BIOS zone 1 is on the next

“BIOS Size” block in the 386 address range (addresses lower than these of Block 1). When FWH is enabled,

BIOS Zone 0 responds to the upper addresses and BIOS Zone 1, if enabled, responds to the group below Zone

0, as deﬁned by BIOS Size. Both zones use the same FWHID value.

0: Disabled - Use BIOS Zone 0 only, if enabled (default)

1: Enabled - If either the LPC BIOS or the FWH BIOS is enabled, use both BIOS Zone 0 and BIOS Zone 1

2-0

BIOSIZE (BIOS Size). Define the Size of one BIOS Zone in the 386 range. Note that by setting the Dual BIOS

Select Enable, two equal-sized BIOS Zones are available.

Bits

2 1 0

Size (Bytes)

0 0 0:

256 Kbytes (default)

0 0 1:

512 Kbytes

0 1 0:

1 Mbyte

0 1 1:

2 Mbytes

1 0 0:

4 Mbytes

1 0 1:

8 Mbytes

1 1 0:

16 Mbytes

1 1 1:

Reserved

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