test equipment / Re: Z80 / Z84C Swap (Doh!)

[Eric Smith]

On Mon, Aug 17, 2015 at 1:54 PM, tony duell <ard at p850ug1.demon.co.uk> wrote:
> One thing though. No piece of test gear will do more than provide evidence of
> what the circuit is doing. It will not tell you 'U38 is faulty' or whatever.

In principle that was where HP was trying to go with signature
analysis back in the 1970s. The problem has since been solved by
making the entire product a single FRU (Field Replaceable Unit).

"He fixes radios by THINKING!"
- Someone who had a young Richard Feynman fix his radio,
  as quoted in his autobiography _Surely You're Joking, Mr. Feynman!
(Adventures of a Curious Character)_