Suggestion for down-the-road designs

[john.r.strohm@xxxxxxx]

Is there a way to make the "pattern vs. number" dichotomy go away?

Years and years ago, I worked on a machine whose program counter ran
backwards.  It didn't really do that: what happened was that target
addresses in jump instructions had to be inverted.  This was OK for
absolute jumps, because the assembler took care of it, but an absolute
crock for computed jumps: everyone complained about having to negate the
final jump address, and LOTS of bugs were introduced by people forgetting
to do it.  The problem went completely away when they adopted the viewpoint
that the program counter was running backwards, and all that was really
necessary was to hang some 7404s in the programmer's console display of the
PC.

I understand it is there because it makes for faster hardware in certain
pathological cases.  I regard this as a bad justification; it seems to be
one of the bigger sticking points for the designers first looking at the
part.