Use of mature ICs in control systems
Chris Scott said:
"PS: Isn't it remarkable that, 20 years on, the SECs may still be employing an Intel 80186 chip, now ancient history in the home-PC world? We were all buying PCs with 80286/80386 chips, even as the A320s were first going into service."
I couldn't let this go! NO, It is not remarkable, it is just good engineering. If a chip performs the designed task within spec it should stay in the design forever. The engineering world is not motivated by specsmanship and marketing like the consumer electronics world is. If you put a more modern chip in there, what benefit is it going to give you? Absolutely none, but what about the risk of mask errors introducing bugs that the original programmers did not test for because the new chip has circuits that were not even known back then? Very probable.
If you re-design with a new chip, you have to re-test all system components, and that costs a lot of money.
I used to make a lot of money keeping old PDP-11s going in Candu nuclear reactors, because they were reliable and every path through the program had been documented and tested for safety.
It's not a matter of keeping up with the Joneses!
Last edited by ve3id; 24th Feb 2008 at 02:31.
Reason: added original attribution