User`s guide

Table C–6 Utility Bus Device Decode
Device Address Select Bits
ecsen_l ecasaddr_2 ecasaddr_1 ecasaddr_0
Device
Select
Signal
Device
Selected
Address
Decode
0000rtcale_l TOY address 70, 72,
74, 76
0001rtccs_l TOY data 71, 73,
75, 77
0010kbcs_l Mouse/
Keyboard
enable
60, 62,
64, 66
0011flashcs_l flash ROM
enable
1
—
0100—Unused —
0101—Unused —
0110—Unused —
0111—Unused —
1000—Unused —
1001—Unused —
1010—Unused —
1011—Unused —
1100—Unused —
1101—Unused —
1110—Unused —
1111—Unused —
1
The encoded chip select signal for flashcs_l will always be generated for accesses to the upper 64KB (at the
top of 1MB, F0000–FFFFF) and its aliases (at the top of the 4GB and 4GB–1MB).
Access to the lower 64KB (E0000–EFFFF) and its aliases (at the top of the 4GB and 4GB–1MB) can be
enabled or disabled through the SIO.
An additional 384KB of BIOS memory (at the top of 4GB, FFFD0000–FFFDFFFF) can be enabled for BIOS
use.
Only one half of the 1MB flash ROM may be accessed at one time. The signal flash_adr19 selects the half as
follows:
flash_adr19 = 0 selects the lower 512KB of flash ROM.
flash_adr19 = 1 selects the higher 512KB of flash ROM.
PCI Address Maps C–11