MPC555
/
MPC556
CENTRAL PROCESSING UNIT
MOTOROLA
USER’S MANUAL
Rev. 15 October 2000
3-11
Where not otherwise noted, reserved fields in registers are ignored when written and
return zero when read. An exception to this rule is XER[16:23]. These bits are set to
the value written to them and return that value when read.
3.7 PowerPC UISA Register Set
The PowerPC UISA registers can be accessed by either user- or supervisor-level in-
structions. The general-purpose registers are accessed through instruction operands.
Table 3-3 Development Support SPRs
1
NOTES:
1. All development-support SPRs are implementation-specific.
SPR Number
(Decimal)
Special-Purpose Register
144
Comparator A Value Register (CMPA)
See
for bit descriptions.
145
Comparator B Value Register (CMPB)
See
for bit descriptions.
146
Comparator C Value Register (CMPC)
See
for bit descriptions.
147
Comparator D Value Register (CMPD)
See
for bit descriptions.
148
Exception Cause Register (ECR)
See
for bit descriptions.
149
Debug Enable Register (DER)
See
for bit descriptions.
150
Breakpoint Counter A Value and Control (COUNTA)
See
for bit descriptions.
151
Breakpoint Counter B Value and Control (COUNTB)
See
for bit descriptions.
152
Comparator E Value Register (CMPE)
See
for bit descriptions.
153
Comparator F Value Register (CMPF)
See
for bit descriptions.
154
Comparator G Value Register (CMPG)
See
for bit descriptions.
155
Comparator H Value Register (CMPH)
See
for bit descriptions.
156
L-bus Support Comparators Control 1 (LCTRL1)
See
for bit descriptions.
157
L-bus Support Comparators Control 2 (LCTRL2)
See
for bit descriptions.
158
I-bus Support Control Register (ICTRL)
See
for bit descriptions.
159
Breakpoint Address Register (BAR)
See
for bit descriptions.
630
Development Port Data Register (DPDR)
See
for bit descriptions.
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Freescale Semiconductor, Inc.
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