Bill; Fairchild is right. Ideas for new instructions often begin with the notion that something ugly ought to be avoidable; but that notion is not enough, even when it has obvious merit.
To take such a notion further it should first be implemented as a macro, perhaps in several ways, complete with diagnostic machinery (and instrumentation that can be disabled). Then, after you have used that macro for a time, and probably after making some iterative improvements in it, you will be in a better position to propose its implementation and to make a case for its usefulness. You will need to be able to make a very good case, one that cannot be shot down because your proposed instruction has some disagreeable side effect. Moreover, the idea that some alternative sequence of several instructions is error-prone, lends itself to abuse, will probably not be persuasive. All instruction sequences lend themselves to misuse by clots. New instruction proposals abound. Many of them are ill-conceived; and few of them get far; most, it would appear, are not even implemented experimentally in multicode. John Gilmore, Ashland, MA 01721 - USA
