Programming Model
http://www.motorola.com/computer/literature
3-37
3
Also note that the combination of RAM_X_BASE and
ram_x_siz should never be programmed such that
DRAM responds at the same address as the CSR,
ROM/Flash, External Register Set, or any other slave on
the PowerPC bus.
CLK Frequency Register
CLK FREQUENCY
These bits should be programmed with the
hexadecimal value of the operating CLOCK frequency in
MHz (for example, $42 for 66 MHz). When these bits are
programmed this way, the chip’s prescale counter
produces a 1 MHz output. The output of the chip prescale
counter is used by the refresher/scrubber and the 32-bit
counter. After power-up, this register is initialized to $42
(for 66MHz).
por
por is set by the occurrence of power up reset. It is cleared
by writing a one to it. Writing a 0 to it has no effect.
ADDRESS
$FEF80020
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
CLK FREQUENCY
0
0
0
0
0
0
0
po
r
OPERATION
READ/WRITE
READ ZERO
READ ZERO
R
R
R
R
R
R
R
R/C
RESET
42 P
X
X
X
X
X
X
X
X
X
1 P