Replacing 27C256 with 28C256, how to wire /WE?
Comparing them side by side you can see the differences:


The '27 has:
a. pin #1, Vpp which in circuit is not used (either Gnd or Vcc)
b. pin #27, A14 which is a driven address line.
The '28 has:
a. pin #1, A14 is a driven address line.
b. pin #27, /WE Which must be tied high in circuit.


When you place the '28 in circuit you must:


Lift pin #1 of the '28 so it does not contact the Vpp pad
Lift Pin # 27 of the '28 so that it does not contact the A14 Pad
solder or join or bridge the lifted pin 27 to Pin #28 of the '28 (tying /WE high)
connect the PAD at Pin location #27 on the board with a blue wire to the lifted pin #1 of the '28. (connecting the address line)