3-50
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Falcon ECC Memory Controller Chipset
3
ROM B Base/Size Register
ROM B BASE
These control bits define the base address for
ROM/Flash Block B. ROM B BASE bits 0-11 correspond
to PowerPC 60x address bits 0 - 11 respectively. For larger
ROM/Flash sizes, the lower significant bits of ROM B
BASE are ignored. This means that the block’s base
address will always appear at an even multiple of its size.
ROM B BASE is initialized to $FF4 at power-up or local
bus reset.
Note that in addition to the programmed address, the first
1Mbyte of Block B also appears at $FFF00000 -
$FFFFFFFF if the rom_b_rv bit is set.
Also note that the combination of ROM_B_BASE and
rom_b_siz should never be programmed such that
ROM/Flash Block B responds at the same address as the
CSR, DRAM, External Register Set, or any other slave on
the PowerPC bus.
rom_b_64 rom_b_64 indicates the width of ROM/Flash
device/devices being used for Block B. When rom_b_64
is cleared, Block B is 16 bits wide, where each Falcon
interfaces to 8 bits. When rom_b_64 is set, Block B is 64
bits wide, where each Falcon interfaces to 32 bits.
rom_b_64 matches the inverse of the value that was on the
CKD3 pin at power-up reset. It cannot be changed by
software.
ADDRESS
$FEF80058
BIT
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
NAME
ROM B BASE
ro
m_
b_6
4
ro
m
b
si
z0
ro
m
b
si
z1
ro
m
b
si
z2
0
0
0
0
0
ro
m_
b_r
v
ro
m b
en
ro
m
b
we
OPERATION
READ/WRITE
R
R/
W
R/
W
R/
W
READ ZERO
R
R
R
R
R
R/
W
R/
W
R/
W
RESET
$FF4 PL
V P
0 PL
0 PL
0 PL
X
X
X
X
X
X
V P
0 PL
0 PL