Unix Error Messages at Crash Time

[ben%brandeis%csnet-relay at sri-unix.UUCP]

Is there anyone out there who knows what Unix error messages at crash time
mean? I am talking about the ones not explained in section 8 of volume 1.
Messages like "panic: mba, zero entry", "unit 0: random interrupt", or 
"machine check". 

CRASH(8) says the following about machine checks:

	 "We should describe machine checks, and will someday. For now,
	  ask someone who knows (like your friendly field service people)."

!!!????!!!