
System Interface Unit
12-20
MPC801 USER’S MANUAL
MOTOROLA
12
SEME—Synchronous External Master Enable
This bit configures how the memory controller refers to external synchronous masters
initiating a transaction. If this bit is set, the memory controller interprets any TS assertion that
the external bus does not own as an external synchronous master initiating a transaction. If
it is reset, the memory controller ignores the value of the TS pin when it does not own the
external bus.
Bits 24 and 28–31—Reserved
These bits are reserved and should be set to 0.
GB5E—GPLB(5) Enable
If this bit is set (1), then the GPLB5 of the memory controller functionality is active. If it is
cleared (0), the BDIP signal functionality is active.
B2DD—Bank 2 Double Drive
If this bit is set (1), then the CS2 signal is reflected onto GPLA2/GPLB2.
B3DD—Bank 3 Double Drive
If this bit is set (1), then the CS3 signal is reflected onto GPLA3/GPLB3.
12.12.1.2 INTERNAL MEMORY MAP REGISTER.
The internal memory map register
(IMMR) is located within the PowerPC special register space. It contains the identification of
a specific device as well as a base for the internal memory map. Based on the value read
from this register, the software can deduce the availability and location of any on-chip
system resource. The contents of this register can be read by the
mfspr
nstruction and the
ISB field can be written by the
mtspr
instruction. However, the PARTNUM and MASKNUM
fields are mask programmed and cannot be changed for any device.
ISB—Internal Space Base
This read/write field defines the base address of the internal memory space. The initial value
of this field can be configured at reset to one of four addresses and changed to any value
by the software. The number of programmable bits in this field and the resolution of the
location of internal space depends on the internal memory space of the specific
implementation.
IMMR
BIT
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
FIELD
ISB
RESET
0
R/W
R/W
BIT
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
FIELD
PARTNUM
MASKNUM
RESET
10
00
R/W
R
R