jim (11/01/82)
Ah yes, the old translation buffer parity fault problem. This is apparently quite common on 750s running Unix. There was a flurry of info about it several months ago, and it seems no one had a good solution other than calling DEC out repeatedly. Did anyone ever come up with a better solution? If so, please post. Our latest 750 has this problem; two older ones don't.
elman (11/03/82)
We had the same problem: periodic machine checks from translation buffer parity faults. This occurred randomly until, by chance, I wrote a program which was able to reliably induce the check. After asking around I discovered that the problem is fairly common, and is associated with an early release of CPU board #3 (rev C or earlier). Fortunately (for us) two other local sites had had this problem and already convinced DEC to replace the board, even though the problem does not show up under DEC diagnostics. So DEC readily came out and swapped us the rev C board for rev E, and the problem went away. This was a month ago. I'm not sure what the basis for the problem is, but there is some interaction with memory. The program that failed on our 750 (which has 1 MB) ran ok on another that has more memory; furthermore, when pared down (it had huge arrays of structures) it would even run ok on our machine. I suggest you ask DEC for a new board 3. The program that produces the error on demand is somewhat large. The sources are huge. I will be happy to mail them out if someone really wants to force the failure, but would prefer not to. It'd be a big file xfer. Jeff Elman Phonetics Lab., Dept. of Linguistics; U. C. San Diego ucbvax!sdcsvax!sdamos!elman or elman@nprdc