How many languages can tell you that byte X of output has been generated from byte Y of input going though such and such steps?

When programming in XSLT it is great to fire up a debugger (let's say oXygen), run your transformation, click on the wrong output and being able to go step-by-step backwards.

How many languages designed before 1999 (yeah, XSLT is 15 years old) can claim to be able to do so?