Motorola MVME1X7P User Manual
4-6
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MCECC Functions
4
Double Bit Error (Cycle Type = Burst Read or Non-Burst Read)
You cannot correct the data that is driven to the local MC680x0 bus.
1. Leave the error in DRAM. (Note that the error is not corrected in
DRAM during the next scrub of that address.)
2. Terminate the cycle with Bus Error (assert TEA
∗
to the local bus) if
so enabled.
3. Log the error if not already logged.
4. Notify the local MPU via interrupt, if so enabled.
Triple (or Greater) Bit Error (Cycle Type = Burst Read or Non-Burst Read)
Some of these errors are detected correctly and are handled the same as a
double-bit error. The rest may show up as "no error" or "single-bit error",
both of which are incorrect.
double-bit error. The rest may show up as "no error" or "single-bit error",
both of which are incorrect.
Cycle Type = Burst Write
Because all of the bits are written during a burst write, no checking is done.
Single Bit Error (Cycle Type = Non-Burst Write)
1. Correct the data read from the DRAM, merge with the write data,
and write the correct, merged data to the DRAM.
2. Terminate the cycle normally. (Assert TA
∗
to the local bus.)
3. Log the error if not already logged.
4. Notify the local MPU via interrupt if so enabled.
Double Bit Error (Cycle Type = Non-Burst Write)
1. Do not perform the write portion of the cycle. (This causes the
location to continue to indicate a non-correctable error when
accessed.)
accessed.)
2. Terminate the cycle normally. (Assert TA
∗
to the local bus.)
3. Log the error if not already logged.