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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