A dilemma skirting the discipline of computer architecture concerns the plausibility of architectural designs. To counter the widely held perception that architecture is a nebulous entity is a proposal to view such designs as specifications of constraints to be satisfied.
ULISES AGUERO and SUBRATA DASGUPTA
THE PLAUSIBILITY PROBLEMOne of Ihe most troublesome issues surrounding the whole discipline of computer architecture concerns the plausibility of architectural design proposals. It is widely felt (if not always explicitly stated) that a description of some new architecture (or architecture component) carries little credibility until and unless the design is supported by some sort of physical implementation.One of the reasons new architectural designs are viewed with a skeptical eye is the traditionally informal nature of such proposals. The very nature of these descriptions with their resulting lack of precision makes it very difficult to assess a design objectively for its feasibility, correctness, or performance. Indeed, one can often neither confirm nor refute the design against any given set of criteria simply because of the informality, ambiguity, and omissions of relevant detail in architectural design proposals [4]. In his tract on the methodology of science, Popper [21] termed statements possessing this lack of testability or refutability as "metaphysical statements," and in this sense architectural designs may legitimately be regarded as "metaphysical proposals."Clearly, the only way by which we can assess such a proposal is by waiting until it is implemented and then transferring our critical attention to the physical system. This, in fact, underlies the empirical, exploratory view of computer design as described, for example, by Wilkes [31]. Alternatively, we can attempt to make our design proposals less metaphysical. This can be achieved in two ways. First, by u.sing a formal architecture description language (ADL), the designer is forced This work has been supporled in parl hy GranI DCR 8408750 from the Nalional Science Foundation.