Glen At the time the suggestion to use the AR instruction as a packed decimal 1 arose, the "workshop" was discussing a package that had to fit into 4K and it was getting very, very close to the limit. Saving just one byte was worth the effort - and ingenuity.
Having had to dreg this item from my repository of Assembler memories, I can even recall the name of the bright spark who suggested it, one Dave Redman - in case he's still active out there. Credit where credit is due. A little bit of effort has even enabled me to recall the author of - nearly all - of the 4K DOS spooling package, one Jim Shields, Mr. DOS in the Wigmore Street IBM UK Field Systems Centre around 1968. Chris Mason ----- Original Message ----- From: "glen herrmannsfeldt" <[EMAIL PROTECTED]> Newsgroups: bit.listserv.ibm-main To: <[email protected]> Sent: Saturday, 04 November, 2006 9:02 AM Subject: Re: Assembler question ... > > >>Suffice to say that it was once proposed that the "Add Register" > >>instruction code, X'1A', could be used as a positive packed > >>decimal "1" > > I suppose that could be done to save one byte. > ... > > I suppose in the early S/360 days one byte might > have mattered. > > -- glen ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
