PowerPC Architecture Compliance
MOTOROLA
MPC823 USER’S MANUAL
7-11
PPC
ARCHITECTURE
7
COMPLIANCE
7.3.7.3.6 Program Interrupt. The MPC823 cannot generate a floating-point exception type
interrupt. Likewise, an illegal instruction type program interrupt is not generated by the core,
but an implementation-dependent software emulation interrupt is generated instead. A
privileged instruction program interrupt is generated for an on-core valid special-purpose
register (SPR) field or any SPR encoded as an external special register if SPR0 =1 and
MSRPR =1, as well as if you try to execute privileged instruction occurred when MSRPR =1.
See Table 6-11 for details.
7.3.7.3.7 Floating-Point Unavailable Interrupt. The MPC823 cannot generate a
floating-point exception type interrupt. An implementation-dependent software emulation
interrupt will be taken when you try to execute floating-point instruction, regardless of
MSRFP.
7.3.7.3.8 Trace Interrupt. A trace interrupt occurs if MSRSE = 1 and any instruction except
rfi is successfully completed or if MSRBE = 1 and a branch is completed. Notice that the trace
interrupt does not occur after an instruction that causes an interrupt. The monitor/debugger
software must change the vectors of other possible interrupt addresses to single-step these
instructions. If this is unacceptable, other debug features can be used. Refer to
registers are set on a trace interrupt:
SRR0—Save/Restore Register 0
Set to the effective address of the instruction following the executed instruction.
SRR1—Save/Restore Register 1
1–4
Set to 0.
10–15
Set to 0.
Other
Loaded from bits 16-31 of the MSR. In the current implementation, Bit 30 of
the SRR1 is never cleared, except by loading a zero value from MSRRI.
MSR—Machine State Register
IP
No change.
ME
No change.
LE
Bits are copied from the ILE.
Other
Set to 0.
Execution resumes at offset x’00D00’ from the base address indicated by MSRIP.
7.3.7.3.9 Floating-Point Assist Interrupt. The floating-point assist interrupt is not
generated by the MPC823. An implementation-dependent software emulation interrupt will
be taken when you try to execute a floating-point instruction.