I have some 27c512 in DIP and in PLCC-32 packages. All are brand new. I try to read them. I have no problems with DIP-packed ICs. They pass “blank test” and return all “FF” during reading.
As opposite, PLCC-32 packed ICs fail “blank test” and if I read them return an array of “F7”. I observe the same picture for three ICs of three different manufacturers.
It looks like both PLCC-32 socket and FWHLPC socket are ready for 29 and 49 series but not for 27 series. Is it a case? Or I missed something?