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(→MM8-EJ) |
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| Regel 5: | Regel 5: | ||
==MM8-EJ== | ==MM8-EJ== | ||
Adresses ending on xxx4 or xxx5 all return zero data, so something is wrong in the adress decoding part or in the stack itself. checking continuity on the X-Y lines of the stack is the first thing to check. | Adresses ending on xxx4 or xxx5 all return zero data, so something is wrong in the adress decoding part or in the stack itself. checking continuity on the X-Y lines of the stack is the first thing to check. | ||
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| + | a test with our DSlogic analyzer reveiled a broken 7442 on position E59 and replacing the chip with a spare did the job. | ||
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| + | That was easy... | ||
Versie van 18 apr 2015 20:05
Repairlog PDP8/f
Our PDP8/f seems to have problems with its two corestacks. bank 0-3 are taken care of by a Keronics 812075A, a onr board/two slots memory card. Bank 4-5 is a DEC MM8-EJ 8k cardstack of three cards. As we have the docs for the 8k MM8-EJ stack, we started troubleshooting that one first
MM8-EJ
Adresses ending on xxx4 or xxx5 all return zero data, so something is wrong in the adress decoding part or in the stack itself. checking continuity on the X-Y lines of the stack is the first thing to check.
a test with our DSlogic analyzer reveiled a broken 7442 on position E59 and replacing the chip with a spare did the job.
That was easy...