Service manual

5-4 AlphaServer 4000/4100 Service Manual
5.1.1 Hard Errors
There are two categories of hard errors:
• System-independent errors detected by the CPU. These errors are processor
machine checks handled as MCHK 670 interrupts and are:
Internal EV5 or EV56 cache errors
CPU B-cache module errors
• System-dependent errors detected by both the CPU and IOD. These errors are
system machine checks handled as MCHK 660 interrupts and are:
CPU-detected external reference errors
IOD hard error interrupts
The IOD can detect hard errors on either side of the bridge.
5.1.2 Soft Errors
There are two categories of soft errors:
• System-independent errors detected and corrected by the CPU. These errors are
CPU module correctable errors handled as MCHK 630 interrupts.
• System-dependent errors that are correctable single-bit errors on the system bus
and are handled as MCHK 620 interrupts.