Non-Conventional Computers

Today, a “computer”, without further qualifications, denotes a rather well-specified kind of object; we’ll consider a computer “non-conventional” if its physical substrate or its organization significantly depart from this de facto norm. Thus, the thousands of literate Greeks that ended up in Rome as secretaries and accountants after the “liberation” of Greece in the second century b.c. would be viewed today as non-conventional computers, even though at that time one certainly couldn’t imagine a more ordinary kind of personal computer. Furthermore, we’ll be more concerned with features that ultimately have to be answerable to physics (the mechanisms by which the logic elements operate, the geometry of interconnection, the overall flow of energy and information) than with architectural variants of a “firmware” nature (reduced instruction set, speculative execution of program branches, etc.).