15 Apr
2002
15 Apr
'02
10:05 a.m.
Richard Erlacher wrote:
I think this was because they expected PAL's to replace TTL. CPLD's now
do that job.
But then with higher CPU speeds, PALs have been the work horse of
address decoding and glue logic enables.
--
Ben Franchuk - Dawn * 12/24 bit cpu *
www.jetnet.ab.ca/users/bfranchuk/index.html
Again, agreed.
PALs are restricted in what they can do, but the
restrictions don't matter for many real-world applications. Perhaps you
want to make an address decoder. Typically you need perhaps 2 or 3 (at
most) product terms of some of the address lines. That fits easily into a
PAL.
They offer flexibility beyond the capability of any PROM, but they don't
replace what a PROM was intended to do. A lot of the special-purpose devices
have gone by the wayside, e.g. the XOR PALs once popular for counters and the
like, and the 'L' and 'R' types in favor of the 'V' types. That
suggests that
the PAL family, truly the simplest of the programmable logic devices, has been
refined considerably. Unfortunately