MasPar, anyone?

From: Bob Shannon <bshannon_at_tiac.net>
Date: Wed Sep 11 23:25:01 2002

The Imlac CPU has a special instruction that generates a TTL signal to
trigger a scope for
debugging, a special 'scope loop' opcode. I'd never seen this before
the Imlac, its been very
handy too!

Tony Duell wrote:

>>I've never heard of a scope loop. What is it?
>>
>
>A tight software (or maybe even microcode) loop that keeps on doing the
>same thing to a particular section of the circuitry. You thus get
>repetitive signals that you can look at on an old-fashioned non-storage
>oscilloscope.
>
>Before most serious repairers had logic analysers, such loops were often
>the only way to observe how parts of the machine behaved at full speed.
>Many diagnostic routines included them (I have certainly seen them
>mentioned in MAINDEC listings, for example).
>
>-tony
>
>
Received on Wed Sep 11 2002 - 23:25:01 BST