Do you have some diagnostic information that points to the processor being bad? Given the age of the machine, the problems could be intermittant connections, bad power supplies etc..
If you have ruled out other problems, then I would suggest getting another M7264-<x>B rather than switching to a different processor. <x> here is refers to different memory chip vendors.
Alternately a M7270 and a few memory board updates or reconfiguration may also work.
Beyond that there are all sorts of complications you would have to investigate before using a different processor such as:
- Floating point FIS instruction requirements.
- Memory board refresh requirements.
- The LSI 11-03/02 will run with odd program addressing defects, while the later cpu's trap and/or halt on them.
- Does the program have any timing dependency on the LSI 11/03.
- Backplane addressing and other differences.
Some of this can be determined from the inventory details. The timing or odd addressing problems typically won't reveal itself until you run the program on the replacement processor.
See http://web.frainresearch.org:8080/projects/pdp-11/lsi-11.php for some detail on the LSI-11 CPU variants.
More DEC fans can be found over at http://www.vcfed.org/forum/forumdisplay.php?23-DEC
Good luck sorting it out,
Jerry
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