5 Nov
2005
5 Nov
'05
8:23 a.m.
On 11/5/2005 at 8:21 AM Jos Dreesen wrote:
The problem with this is of course that the CPLD and
even more the
FPGA's
will be obsolete and unobtainum long before the TTL parts are really
gone.
You can still buy a 74ls181., but try a 10 year old FPGA...
...and DIP-based TTL (and CMOS) is more "harvestable". Before I toss out
an old board with lots of DIPs on it, I think really hard about getting out
the propane torch and removing the chips on it. If the chips are SMT, it
goes into the trash without a second thought.
A friend, after retirement, has made a small career of working on Ruffatti
pipe organs. Instruments made in the 70's and 80's rely on a bunch of TTL
and an MPU (I think it's 8086, but not sure) for the adjustable combination
stop mechanism. The outfit that designed it for Ruffatti and did the
programming is long gone, not having left any documentation. Fortunately,
the logic's made of standard parts, the MPU has a well-documented
instruction set and it's not hard to get a probe on pins to figure out
what's going on--and one can purchase replacements. I shudder to think of
what would have happened if these things had been FPGAs. An instrument
like this can have a life of several hundred years and go more than 100
years between renovation.
Cheers,
Chuck