The main
difference is the power consumption. The CMOS version takes a
much lower supply current (even when selected).
There may also be differences in the access time (but fast enough CMOS
EPROMs exist) and the programming algorithm (but that only matters to the
programmer).
They are essentially pin/function compatible.
Erm, correct me if I'm wrong ('cause I may very well be) but at least in
comparison with 4xxx CMOS vs. 74xx TTL, not only do the require less
power
to do their job, but they can also *provide* less
power on their outputs
to
other chips' inputs, right?
Hmm. You're comparing CMOS with TTL. The traditional EPROMs are not TTL
but NMOS - very similar components (at the transistor level) to CMOS, but
fewer different sorts available. NMOS uses enhancement mode FETS and
depletion mode FETS of N-channel polarity. CMOS uses enhancement mode FETS
of both sorts. In theory, depletion mode FETS could be fabricated by the
CMOS process, but I've never heard of it being done except perhaps for
NMOS-compatible outputs etc.
So I don't envisage a difficulty here. The newer designs of CMOS parts
should compensate for any inherent disadvantages with CMOS technology.
Philip.