
4-22
MPC603e & EC603e RISC Microprocessors User's Manual
MOTOROLA
4.5.2.1 Machine Check Exception Enabled (MSR[ME] = 1)
When a machine check exception is taken, registers are updated as shown in Table 4-10.
When a machine check exception is taken, instruction execution for the handler begins at
offset 0x00200 from the physical base address indicated by MSR[IP].
In order to return to the main program, the exception handler should do the following:
1. SRR0 and SRR1 should be given the values to be used by the
rfi
instruction.
2. Execute
rfi
.
4.5.2.2 Checkstop State (MSR[ME] = 0)
When the 603e enters the checkstop state, it asserts the checkstop output signal,
CKSTP_OUT. The following events will cause the 603e to enter the checkstop state:
Machine check exception occurs with MSR[ME] cleared.
External checkstop input, CKSTP_IN, is asserted.
An extended transfer protocol error occurs.
When a processor is in the checkstop state, instruction processing is suspended and
generally cannot be restarted without resetting the processor. The contents of all latches are
frozen within two cycles upon entering the checkstop state so that the state of the processor
can be analyzed as an aid in problem determination.
Table 4-10. Machine Check Exception—Register Settings
Register
Setting Description
SRR0
Set to the address of the next instruction that would have been completed in the interrupted
instruction stream. Neither this instruction nor any others beyond it will have been completed. All
preceding instructions will have been completed.
SRR1
0–11
12
13
14
15
16–31 Loaded from MSR[16–31].
Cleared
MCP—Machine check signal caused exception
TEA—Transfer error acknowledge signal caused exception
DPE—Data parity error signal caused exception
APE—Address parity error signal caused exception
MSR
POW 0
TGPR0
ILE
IP
—
—
EE
PR
FP
1
ME
0
0
0
—
FE0
2
0
SE
BE
FE1
2
0
0
0
IR
DR
RI
LE
0
0
0
Set to value of ILE
Note that when a machine check exception is taken, the exception handler should set MSR[ME] as
soon as it is practical to handle another TEA assertion. Otherwise, subsequent TEA assertions
cause the processor to automatically enter the checkstop state.
Notes:
1. The floating-point available bit is always cleared to 0 on the EC603e microprocessor.
2. FE0 and FE1 are not supported on the EC603e microprocessor.