Problems With The Counter Machine Model
- The problems are discussed in detail in the article Random access machine. The problems fall into two major classes and a third "inconvenience" class:
(1) Unbounded capacities of registers versus bounded capacities of state-machine instructions: How will the machine create constants larger than the capacity of its finite state machine?
(2) Unbounded numbers of registers versus bounded numbers of state-machine instructions: How will the machine access registers with address-numbers beyond the reach/capability of its finite state machine?
(3) The fully reduced models are cumbersome:
Shepherdson and Sturgis (1963) are unapologetic about their 6-instruction set. They have made their choice based on "ease of programming... rather than economy" (p. 219 footnote 1).
Shepherdson and Sturgis' instructions ( indicates "contents of register r"):
-
- INCREMENT ( r ) ; +1 → r
- DECREMENT ( r ) ; -1 → r
- CLEAR ( r ) ; 0 → r
- COPY ( rs to rd ) ; → rd
- JUMP-UNCONDITIONAL to instruction Iz
- JUMP IF =0 to instruction Iz
Minsky (1967) expanded his 2-instruction set { INC (z), JZDEC (r, Iz) } to { CLR (r), INC (r), JZDEC (r, Iz), J (Iz) } before his proof that a "Universal Program Machine" can be built with only two registers (p. 255ff).
Read more about this topic: Counter Machine
Famous quotes containing the words problems with, problems, counter, machine and/or model:
“I was a wonderful parent before I had children. I was an expert on why everyone else was having problems with theirs. Then I had three of my own.”
—Adele Faber (20th century)
“I’m no good at being noble, but it doesn’t take much to see that the problems of three little people don’t amount to a hill of beans in this crazy world. Someday you’ll understand that.”
—Julius J. Epstein, U.S. screenwriter, Philip Epstein, screenwriter, Howard Koch, screenwriter, and Michael Curtiz. Rick Blaine (Humphrey Bogart)
“Often, when there is a conflict between parent and child, at its very hub is an expectation that the child should be acting differently. Sometimes these expectations run counter what is known about children’s growth. They stem from remembering oneself, but usually at a slightly older age.”
—Ellen Galinsky (20th century)
“The momentary charge at Balaklava, in obedience to a blundering command, proving what a perfect machine the soldier is, has, properly enough, been celebrated by a poet laureate; but the steady, and for the most part successful, charge of this man, for some years, against the legions of Slavery, in obedience to an infinitely higher command, is as much more memorable than that as an intelligent and conscientious man is superior to a machine. Do you think that that will go unsung?”
—Henry David Thoreau (1817–1862)
“She represents the unavowed aspiration of the male human being, his potential infidelity—and infidelity of a very special kind, which would lead him to the opposite of his wife, to the “woman of wax” whom he could model at will, make and unmake in any way he wished, even unto death.”
—Marguerite Duras (b. 1914)