21-18
MPC561/MPC563 Reference Manual
MOTOROLA
Programming Model
Table 21-6. RCW Bit Descriptions
Bits
Name
Description
0
EARB
arbitration. The default value is that internal arbitration hardware is used.
0 Internal arbitration is performed
1 External arbitration is assumed
1
IP
Initial interrupt prefix — This bit defines the initial value of the MSR[IP] immediately after reset. The
MSR[IP] bit defines the Interrupt Table location.
0 MSR[IP] = 0 after reset
1 MSR[IP] = 1 after reset
The default value is 0. See
Table 3-11 for more information.
2
BDRV
Bus pins drive strength — This bit determines the bus pins’ (address, data, and control) driving capability
to be either full or reduced drive. The bus default drive strength is full; upon default, it also causes the
CLKOUT drive strength to be full. See
Table 6-7 for more information. BDRV controls the default state
of COM[1] in the SIUMCR.
0 Full drive
1 Reduced drive
3
BDIS
Boot disable — If the BDIS bit is set, then memory controller is not activated after reset. If it is cleared
then the memory controller bank 0 is active immediately after reset such that it matches any addresses.
If a write to the OR0 register occurs after reset this bit definition is ignored. The default value is that the
0 Memory controller bank 0 is active and matches all addresses immediately after reset
1 Memory controller is not activated after reset.
4:5
BPS
Boot port size — This field defines the port size of the boot device on reset (BR0[PS]). If a write to the
OR0 register occurs after reset this field definition is ignored. See
Table 10-6 and
Table 10-9 for more
information.
00 32-bit port (default)
01 8-bit port
10 16-bit port
11 Reserved
6:8
—
Reserved. These bits must not be high in the reset configuration word.
9:10
DBGC[0:1]
this field definition. The default value is that these pins function as: VFLS[0:1], BI, BR, BG and BB. See
11
—
Reserved.
12
ATWC
Address type write enable configuration — The default value is that these pins function as WE pins.
0WE[0:3]/BE[0:3]/AT[0:3] functions as WE[0:3]/BE[0:3]
1WE[0:3]/BE[0:3]/AT[0:3] functions as AT[0:3]
13:14
EBDF
External bus division factor — This field defines the initial value of the external bus frequency. The
default value is that CLKOUT frequency is equal to that of the internal clock (no division). See
Table 8-9.