Quote:
Originally Posted by aeberbach
Don’t forget you need to erase 27c400 as well. They are erased with UV by exposing the window and applying intense UV light for 6o minutes or so. If you only want to burn one ROM once and you get a blank ROM that’s fine but if you get it wrong then you have to erase it...
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Too long exposure for UV may kill EPROM permanently. I assume every software is able to verify if EPROM is clean/erased - if not then read EPROM and check for content - it should have all data bits equal to 1 (so 8 bit will be $FF and 16 bit $FFFF).
It is recommended during erasing process (UV exposure) to short all pins in EPROM with conductive foam/aluminum foil to prevent EPROM damage (also grounding is recommended) - commonly professional erasers providing such grounding by special design.