Motorola MVME2400 Series Wartungshandbuch Seite 245

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Programming Model
http://www.mcg.mot.com/literature 3-59
3
rom b we When rom b we is set, writes to Block B ROM/Flash are
enabled. When rom b we
is cleared they are disabled.
Refer back to Table 3-13 for more details.
ROM Speed Attributes Registers
rom_a_spd0,1
rom_a_spd0,1 determine the access timing used for
ROM/Flash Block A. The encoding of these bits are
shown in Table 3-15.
The device access times shown in the table are
conservative and allow time for buffers on address,
control, and data signals. For more accurate information
see the section entitled “Timing Specifications for
ROM/Flash Signals” further on in this manual, along with
the section titled “ROM/Flash Read Timing Diagram”.
Writes that change these bits must be enveloped by a
period of time in which no accesses to ROM/Flash Block
A, occur. A simple way to provide the envelope is to
perform at least two accesses to this or another of the
SMC’s registers before and after the write.
ADDRESS
$FEF80060
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
0
0
rom a spd0
rom a spd1
0
0
rom b spd0
rom b spd1
OPERATION
READ ZERO READ ZERO READ ZERO
R
R
R/W
R/W
R
R
R/W
R/W
RESET
XXX
X
X
0 PL
0 PL
X
X
0 PL
0 PL
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