Actually, you don't remember the origin, you remember an uninformed instructor feeding you an invented etymology. The usage precedes the S/360 by years; it dates to the 709 if not before. See, e.g., the FAP manual on bitsavers.
-- Shmuel (Seymour J.) Metz http://mason.gmu.edu/~smetz3 ________________________________________ From: IBM Mainframe Assembler List [ASSEMBLER-LIST@LISTSERV.UGA.EDU] on behalf of jba...@ngssallc.com [jba...@ngssallc.com] Sent: Thursday, April 30, 2020 10:14 PM To: ASSEMBLER-LIST@LISTSERV.UGA.EDU Subject: Re: *-* I must really be getting old, because I actually remember the origin of the convention. The convention of "*-*" in a length field was based upon an interpretation of the expression "{address-of-last-byte}-{address-of-first-byte}" which calculates the "machine length" of the field, which is one less than the actual length of the field. When moving a variable length field, the instruction had to be "EX(ecuted)", so the programmer likely did not know the value of "{address-of-last-byte}" at assembly time and in many cases did not know the value of "{address-of-first-byte}" at assembly time, so the programmer simply replaced each unknown with "*" and voila, we had "*-*". We discussed this in assembler programming class some 47 years ago. John P. Baker Software Developer -----Original Message----- From: IBM Mainframe Assembler List <ASSEMBLER-LIST@LISTSERV.UGA.EDU> On Behalf Of robi...@dodo.com.au Sent: Thursday, April 30, 2020 4:46 AM To: ASSEMBLER-LIST@LISTSERV.UGA.EDU Subject: Re: *-* On 2020-04-30 18:15, Martin Ward wrote: > On 30/04/2020 03:48, robi...@dodo.com.au wrote: >> >> What's wrong with a comment? > > It *is* a comment (in the broader sense). No it isn't. *-* doesn't explain anything. If it did, people wouldn't be asking what on earth is it. A comment that explains that the length is planted by some other instruction or whatever else is it, is the only way to document it.
