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Programming Model
http://www.motorola.com/computer/literature
3-57
3
Power-Up Reset Status Register 2
PR_STAT2 (power-up reset status) reflects the value that was on the
RD32-RD63 signal pins at power-up reset. This register is read-only.
External Register Set
The EXTERNAL REGISTER SET is user provided and is external to the
Falcon pair. The Falcon pair provides a static RAM style interface for the
external registers. The external registers can be SRAM, ROM, Flash or
some other user device. There can be one device connected to either the
upper or lower Falcon, or there can be two devices with one connected to
each Falcon. The devices can be 8, 16, or 32 bits wide. The data path to the
external devices is via the RD32-RD63 pins. Reads to the external devices
can be any size except burst. Note that if the devices are less than 32 bits
wide, reads to unused data lanes will yield undefined data. Note that writes
are restricted to one or 4-byte length only. 4-byte writes can be used for any
size device, data should be placed on the correct portion of the data bus so
that valid data is written to the device. Data duplication is turned off for the
EXTERNAL REGISTER SET so writes can be to either the upper
Falcon, or to the lower Falcon.
Address
$FEF80500
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
PR_STAT2
Operation
READ
Reset
V P
Address
$FEF88000 - $FEF8FFF8
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
EXTERNAL REGISTER SET
Operation
READ/WRITE
Reset
X PL