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From: Stefan Monnier <monnier@iro.umontreal.ca>
Newsgroups: comp.arch
Subject: Re: control co-processor
Date: Mon, 05 May 2025 10:02:58 -0400
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> Even state-of-the-art CPUs today commonly use scan-chains (via JTAG)
> for debuggin.

Is there some blog somewhere that explains how scan-chains work (not
how they're used, but how they're implemented inside the CPU)?
Intuitively they sound very costly to me, because of things like the
need to run extra wires all over the place.  I'm obviously
missing something.


        Stefan