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Old 12th Apr 2021, 3:24 pm   #1576
ortek_service
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Join Date: May 2018
Location: Northampton, Northamptonshire, UK.
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Default Re: Non-working Commodore PET 3016

That's what I had thought at first, with the 74LS145's BCD-Input 'A' bit pin not functioning, being stuck high or low. So only half of the (Row) outputs from it were going low.

However, whilst trying to explain to Colin why the 74LS145 must be faulty from what we'd seen, I then realised that if only half of the (Row) outputs from it went low, then half of the keys on the matrix wouldn't actually do anything at all - Rather than what had been found in that all Key presses are detected, but half in the wrong (adjacent) Row.

Hence my explanation of about the only way I could see what was occurring
- even though it did seem to be a very strange internal failure of a 74LS145
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