buying an oscilloscope

[Eric Smith]

Gerhard wrote about a 100 MHz oscilliscope:
>    For slow signals usually present in classical hardware, thats no
> problem.

That's true.

Many people have the mistaken belief that a 'scope with 20 MHz bandwidth
is adequate for looking at 20 MHz digital signals, but that is not true.
For digital signals you usually want bandwidth of at least five times the
peak frequency of the system, and preferably more.  It's hard to
diagnose problems when fairly square edges on signals look like
sine waves on the 'scope.

Eric