FWIW, sometimes an alias shows up in HLASM before it gets added to PoOps. -- Shmuel (Seymour J.) Metz http://mason.gmu.edu/~smetz3 עַם יִשְׂרָאֵל חַי נֵ֣צַח יִשְׂרָאֵ֔ל לֹ֥א יְשַׁקֵּ֖ר
________________________________________ From: IBM Mainframe Discussion List <[email protected]> on behalf of Tony Thigpen <[email protected]> Sent: Friday, August 8, 2025 7:15 AM To: [email protected] <[email protected]> Subject: Re: Why LLC? Why not LLB? External Message: Use Caution Seymour, I just grabbed my 2022 Reference Summary and looked at the chart. There are so many patterns, yet several exceptions. I can just hear a hardware person saying: "I can add the function to the chip, but you will need to add more letters to the alphabet before we can give it a mnemonic." I wonder if the hardware guys assign the mnemonic, or if the assembler developers assign it? (Based on some of the names, I am betting the hardware guys.) Tony Thigpen Seymour J Metz wrote on 8/8/25 6:40 AM: > And R was register. > > So besides B, G, H, I, L, R, and Y, what other letters have new meaning? > > -- > Shmuel (Seymour J.) Metz > http://mason.gmu.edu/~smetz3 > עַם יִשְׂרָאֵל חַי > נֵ֣צַח יִשְׂרָאֵ֔ל לֹ֥א יְשַׁקֵּ֖ר > > > > > ________________________________________ > From: IBM Mainframe Discussion List <[email protected]> on behalf of > Tony Thigpen <[email protected]> > Sent: Friday, August 8, 2025 1:38 AM > To: [email protected] <[email protected]> > Subject: Re: Why LLC? Why not LLB? > > > External Message: Use Caution > > > I just look at it from this view: > > Normally, 'C' in an instruction mnemonic indicates character actions, > not numeric actions. 'P' indicated packed decimal actions. And, the > absence of such indicated the default numeric actions. > > (At least, before all the new stuff.) > > So, for numeric, it was 'L' was a fullword, and 'LH' is a halfword' and > 'LB' for a byte. It could just as easily been Load Numeric ('LN', 'LHN' > and 'LBN') but the original designers did not go that way. Maybe for > less keystrokes on punch cards because these were the more common > instructions used? > > Tony Thigpen > > David Cole wrote on 8/6/25 3:18 PM: >> I apologize is my initial post was unclear. My question is about IBM's >> choice of instruction names, not about functionality. >> >> Also, this has nothing whatsoever to do with the C language. >> >> Let me edit my post and re-present it here... >> >> >> >> In Principles, these two machine instructions are presented: >> - LB loads a byte into a register and sign-extends it. >> - LLC also loads a byte into a register but then zero pads it. >> That's all pretty clear, but... >> >> >> >> My question is, why did IBM choose have the instruction's name end with >> B in one case and with C in the other? >> - On the one hand, Why didn't they choose LC (instead of LB) as >> that instruction's name? >> - Or on the other, why didn't they choose LLB (instead of LLC) as >> that instruction's name? >> >> >> >> Just curious. >> >> Dave Cole >> >> >> >> >> >> At 8/6/2025 05:42 AM, David Cole wrote: >>> In Principles: >>> - LB loads a byte into a register and sign-extends it. >>> - LLC also loads a byte into a register but then zero pads it. >>> That's all pretty clear, but... >>> >>> Why use B in one case and C in the other? >>> - Why not LC instead of LB? >>> - Or why not LLB instead of LLC? >>> >>> "Inquiring minds what to know." >>> >>> Dave Cole >>> >>> ---------------------------------------------------------------------- >>> For IBM-MAIN subscribe / signoff / archive access instructions, >>> send email to [email protected] with the message: INFO IBM-MAIN >> >> ---------------------------------------------------------------------- >> For IBM-MAIN subscribe / signoff / archive access instructions, >> send email to [email protected] with the message: INFO IBM-MAIN > > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to [email protected] with the message: INFO IBM-MAIN > > > > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to [email protected] with the message: INFO IBM-MAIN ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
