Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!cs.utexas.edu!know!zaphod.mps.ohio-state.edu!sdd.hp.com!decwrl!uunet!willett!ForthNet From: ForthNet@willett.UUCP (ForthNet articles from GEnie) Newsgroups: comp.lang.forth Subject: What should the Standard include? Message-ID: <1468.UUL1.3#5129@willett.UUCP> Date: 6 Aug 90 03:28:30 GMT Organization: String, Scotch tape, and Paperclips. (in Pgh, PA) Lines: 69 Category 10, Topic 30 Message 88 Sun Aug 05, 1990 R.BERKEY [Robert] at 06:42 PDT ---------------------------------------------------------------------- ANSI X3J14 Forth Technical Proposal Page 1 of 1 ---------------------------------------------------------------------- Title: One's- and Two's-Complement ALUs Related Proposals: Keyword(s): Proposal (X) Forth Word(s): Comment ( ) ---------------------------------------------------------------------- Abstract: Policy statement for ALUs covered by BASIS. ------------------ Discussion: Removing a bit pattern for zero as was passed in Melbourne, on behalf of a generalized concept of ALUs, is useless to today's programmers, and radically impacts upward compatibility. Without the corresponding analysis and proposals for separating the number concept of "zero" from the flag concept of "false", the BASIS document is rendered inconsistent. For example, IF is currently a word without a clear meaning. Given Forth's lack of penetration into the "sign-magnitude market", specifications for sign-magnitude ALUs are untestable. Without the experience of actual needs, or evidence of such need, the specifications may or may not serve a useful purpose. But nothing in BASIS prevents Forth from being brought up on a sign-magnitude machine. Further, such concepts adversely impact useful programming and upward compatibility. _The_ _fundamental working concept that the conventional Forth number space is_ _circular, is demonstrated in BASIS in the definition of WITHIN and the_ _specification concerning overflow, as well as in previous standards._ The inclusion of one's-complement-ALUs considerations is also outside the scope of ordinary Forth programming. However, the inclusion of one's-complement ALUs with two's-complement ALUs, which are both circular number spaces, is less radical than the inclusion of sign-magnitude, etc., ALUs; there is existing practice in the field; and one of the committee's members is able to represent the one's complement needs. This proposal, among other things, mitigates the potential for oversights in BASIS in specification involving one's complement ALUs, specification which is needed by standard programs. By defaulting to two's complement in the absence of a label that ideas from other ALUs are involved, such labeling serves the purpose of communication of programming ideas: this is consistent with current literature. ------------------- Proposal: It is the policy of the committee to primarily consider only one's and two's complement architectures. The various labeling for "standard programs" will provide labeling for one's complement as a special case. --------------------------------------------------------------------- Submitted by: Robert Berkey Date: 90-08-05 Address: 47000 Warm Springs Blvd. #253 Ph: (415) 659-1334 Fremont, CA 94539 Msgs: GEnie R.BERKEY ANSI X3J14 Forth Standards Committee 111 N. Sepulveda Blvd., Suite 300, Manhattan Beach, CA 90266 --------------------------------------------------------------------- ----- This message came from GEnie via willett through a semi-automated process. Report problems to: uunet!willett!dwp or willett!dwp@hobbes.cert.sei.cmu.edu