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Old 27th Mar 2021, 11:19 pm   #276
circuitryboy
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Join Date: Jun 2012
Location: Bristol, UK.
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Default Re: I found it! A very sorry looking MK14.

I hadn't seen that "Christopher" 2014 posting before.
In 2019 I showed that the Tesla PROMs (MH74-188, -S287, and -S571) had those similar part numbers and used exactly the same programming protocol as the earliest TI (SN74-) PROMs. But TI didn't have a '571.
The TI data shows the '287 programs 'the other way'. I'm not sure why "Christopher" believes the MH74S287 does not. He wasn't using them, just warning to check the datasheet.
Later TI PROMs have different prefixes and require other/more voltages in their programming sequence.
How far back do the Tesla chips date? Certainly to 1989.
Remember that rogue "MH74S571" page in German which confusingly indicated 21V?
It's actually a page of Fairchild 93438 from a databook published in DDR, 1989. The MH74S571 was described immediately before that (without programming details). And somebody didn't notice the change.
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