Need help on old parts??

From: R. D. Davis <rdd_at_smart.net>
Date: Wed Sep 6 16:15:46 2000

On Wed, 6 Sep 2000, Tony Duell wrote:
> Oh come on!. There are places for programmable logic, but this sure isn't
> one of them.

Yes, that's what I think as well.

> One of the rules that I work to when repairing a classic computer is to
> replace as little as possible (==keep as much of the original stuff as
> possible). So you repair a PCB rather than replacing it. You replace only
> the faulty component, not great blocks of logic. Why replace stuff that's
> working properly?

In addition, those PALs/GALs will most likely fail before the rest of
the other older components would have failed. It makes no sense to
replace that which is working properly... but then, society has become
conditioned to such lunacy. Look at how many people keep buying new
cars, when the cars they were driving 20 or more years ago would still
be running well had they kept and properly maintained them and not
been susceptible to marketing gimmickry. ...and,over here in the
States, we'd not have become so dependant on "the spying Japanese," to
quote the Dire Straits song "Industrial Disease." (off topic: funniest
thing I've read in a while: a review for a Japanese pickup truck
announced that it towed a horse-trailer loaded with 300-lbs of weight
(no moving horses) up a steep hill... ROFL!)

> A PAL/GAL is not going to drop in place of this chip. For one thing,
> there are no known 14 pin PALs. For another, no PAL that I've ever seen
> has outputs on the left (like pin 6 of the 7422). So it's going to
> involve some kludge-wiring.

Bletch. Is this what the art of repairing things is degenerating into?

> Especially as there's a TTL chip (the 7422) that will drop in place of
> the DTL part. The only possible mod would be adding a pull-up from pin 6
> and pin 8 to Vcc. Not exactly a big mod.

Yes, true, but it's not modern and wasteful... Could not a great
Monty Python skit be made from this?

--
R. D. Davis                   "The best way to gain a true understanding of
rdd_at_perqlogic.com             Wile E. Coyote on the Roadrunner cartoons is to 
http://www.perqlogic.com/rdd  fly, head-first, off a horse into something like
410-744-4900                  a fence or a tree; trust me, this works." --RDD  
Received on Wed Sep 06 2000 - 16:15:46 BST

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