https://www.ibm.com/support/pages/sites/default/files/2021-05/SA22-7871-10.pdf
includes a list of assembler Instructions.


On Wed, Aug 6, 2025 at 2:22 PM David Cole <[email protected]> wrote:

> 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
> >
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-- 
Mike A Schwab, Springfield IL USA
Where do Forest Rangers go to get away from it all?

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