I was having problems reading some Microchip eeproms in an old Panasonic phone. Newer phones had similar eeproms and I could read and write fine but the old ones would read all 0s (not blank FFFF) and blank check would fail… could not write (program) and verify would fail.
I thought maybe my Minipro programmer was broken so I ordered a cheap EZP2019+ but that had the same issue
I could read / write / verify the 93C56W with no problems on both programmers!
After many hours searching on google I never did find a similar issue or explanation that would help me figure out what I needed to do. But at my last glance at a datasheet I saw this little note:
A little barely mentioned fact that some 93LCxx eeproms have a rotated pinout!
I had tried setting my programmer to 93LC46B (BX was not available) and thought that would be the closest match.
NOPE! But when I selected 93LC46X THEN the programmer would read and write to the IC.
So maybe this will show up for someone else searching google for an answer. If you cannot read a Microchip eeprom 93LC46 or 93LC56 or 93LC66, etc… maybe try the rotated pinout option in your programmer (part number ending in X on my Minipro programmer)
If you don’t have the option of selecting a rotated IC in your programmer you could make or buy an adapter