17 Sep
2007
17 Sep
'07
3:41 a.m.
So the question of the minute is this, is it
possible to substitute a
27C256 for a smaller 27C128?
Sure is. The pinout is nearly the same, save for pin
27. On the 128, it's the program voltage pin, but on
the 256 it's an address line. When programming your
chip, put your data in both banks (i.e., put it in
twice - copy your file and cat the two together into
one file) and burn that to the chip, being sure to
tell your programmer the truth about the chip. Then,
when you put it into the circuit, be sure that pin 27
is tied either high or low - not left floating.
-Ian