Map and Paging Control Register
50
– Reference
VSBC-8 Reference Manual
Map and Paging Control Register
MPCR (READ/WRITE) 00E3h (or 1E3h via CMOS Setup)
D7
D6
D5
D4
D3
D2
D1
D0
FPGEN
DPGEN
SPGEN
SB-SEL
VB-SEL
PG2
PG1
PG0
Table 31: Map and Paging Control Register Bit Assignments
Bit
Mnemonic
Description
D7
FPGEN
FLASH Paging Enable
— Enables a 64K page frame from E0000h to
EFFFFh. Used to gain access to the on-board FLASH memory.
FPGEN = 0
FLASH page frame disabled.
FPGEN = 1
FLASH page frame enabled.
Note!
This bit is for factory use only. It is used to write user default CMOS setup
values to FLASH and to upgrade the system BIOS. When FPGEN = 1, the Page Select
bits are used to access various blocks within the FLASH.
D6
DPGEN
DiskOnChip Enable
— Enables a 64K page frame from E0000h to EFFFFh.
Used to gain access to the Disk on Chip
DPGEN = 0
DOC page frame disabled.
DPGEN = 1
DOC page frame enabled.
Note!
The Page Select bits are not used when accessing the DOC.
D5
SPGEN
Battery Backed Static RAM Paging Enable
— Enables a 64K page frame
from E0000h to EFFFFh. Used to gain access to an optional Dallas
Semiconductor Battery-Backed Static RAM chip plugged into socket U20
(512KB max.)
SPGEN = 0
BBSRAM page frame disabled.
SPGEN = 1
BBSRAM page frame enabled
Note!
When SPGEN = 1, the Page Select bits are used to access various 64K blocks
within the BBSRAM chip.
D4
SB-SEL
System BIOS Selection
— Indicates the status of jumper V8[1-2]
SB-SEL = 0
Jumper out, Secondary System BIOS selected.
SB-SEL = 1
Jumper in, Primary System BIOS selected.
Note!
This bit is a read-only bit.
D3
VB-SEL
Video BIOS Selection
— Indicates the status of jumper V8[3-4]
VB-SEL = 0
Jumper out, Secondary Video BIOS selected.
VB-SEL = 1
Jumper in, Primary Video BIOS selected.
Note!
This bit is a read-only bit.
D2-D0
PG2-PG0
Page Select
— Selects which 64K block of FLASH or BBSRAM will be mapped
into the page frame at E0000h to EFFFFh
Memory Range within
PG2
PG1
PG0
FLASH
0
0
0
000000h to 00FFFFh
0
0
1
010000h to 01FFFFh
0
1
0
020000h to 02FFFFh
0
1
1
030000h to 03FFFFh
1
0
0
040000h to 04FFFFh
1
0
1
050000h to 05FFFFh
1
1
0
060000h to 06FFFFh
1
1
1
070000h to 07FFFFh
