6 Jan
2011
6 Jan
'11
8:22 p.m.
On Thu, Jan 6, 2011 at 8:43 PM, Dave McGuire <mcguire at neurotica.com> wrote:
?It's a bit tougher when they're registered
and can maintain (relatively)
complex state, though. ?Many (most?) PALs are registered.
When I used to work with real MMI PALs in the 1980s, we used *lots* of
"H" and "L" parts with only about 5% "R" (Registered) parts
(10H8,
14L2...) Could have been a cost thing. Could have been a designer
prejudice thing.
GALs, though, are a different story, since AFAIK, for all intents and
purposes, all outputs are registered (but the flip-flop can be
bypassed if the logic terms don't "activate" it). I haven't fully
explored GAL complexity, but my understanding is that for the same
size of package, one GAL can assume the function of any of the PALs
its size (i.e., a 16V8 can be programmed as a drop-in replacement for
a 10H8 or 16L2 or 12R6, etc).
Then there's the security bit. I don't think we ever set it on ours,
but companies paranoid about knockoffs did.
-ethan