
4-34
MPC8260 PowerQUICC II User’s Manual
MOTOROLA
Part II. Configuration and Reset
4.3.2.7 Internal Memory Map Register (IMMR)
The internal memory map register (IMMR), shown in Figure 4-29, contains identification
of a specific device as well as the base address for the internal memory map. Software can
deduce availability and location of any on-chip system resources from the values in IMMR.
PARTNUM and MASKNUM are mask programmed and cannot be changed for any
particular device.
Table 4-13 describes IMMR fields.
Bit
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Field
ISB
—
Reset
Depends on reset configuration sequence. See Section 5.4.1, “Hard Reset Configuration Word.”
R/W
R/W
Addr
0x101A8
Bit
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
Field
PARTNUM
MASKNUM
Reset
—
R/W
R
Addr
0x101AA
Figure 4-29. Internal Memory Map Register (IMMR)
Table 4-13. IMMR Field Descriptions
Bits
Name
Description
0–14
ISB
Internal space base. Defines the base address of the internal memory space. The value of ISB
be configured at reset to one of 32 addresses; it can then be changed to any value by the
software. The default is 0, which maps to address 0x0000_0000.
ISB defines the 15 msbs of the memory map register base address. IMMR itself is mapped in
the internal memory space region. As soon as the ISB is written with a new base address, the
IMMR base address is relocated according to the ISB. ISB can be configured to one of 32
possible addresses at reset to enable the configuration of multiple-MPC8260 systems.
The number of programmable bits in this field, and hence the resolution of the location of
internal space, depends on the internal memory space of a specific implementation. In the
MPC8260, all 15 bits can be programmed. See Chapter 3, “Memory Map,” for details on the
device’s internal memory map and to Chapter 5, “Reset,” for the available, default initial values.
15
—
Reserved, should be cleared.
16–23
PARTNUM
Part number. This read-only field is mask-programmed with a code corresponding to the part
number of the part on which the SIU is located. It is intended to help factory test and user code
which is sensitive to part changes. This changes when the part number changes. For example,
it would change if any new module is added or if the size of any memory module is changed. It
would not change if the part is changed to fix a bug in an existing module. The MPC8260 has an
ID of 0x00.
24–31
MASKNUM Mask number. This read-only field is mask-programmed with a code corresponding to the mask
number of the part on which the SIU is located. It is intended to help factory test and user code
which is sensitive to part changes. It is programmed in a commonly changed layer and should
be changed for all mask set changes. The MPC8260 (Rev 0) has an ID of 0x00.