registers(0-15) ,where they are going be resides., does
that mean here is it resides whether real or virtual
memory? and why?
then why we are assign even registers(0 to 6) for FP
operations????
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Answer / guest
Registers are part of the CPU logic and should not be
confused with memory real or virtual. The question is
about as sensical as asking where the uterus resides in a
man. Also, general purpose registers 0--16 are an
entirely different breed that the floating point
registers. As for the numbering, a decision made by the
manufacturer's design people.
| Is This Answer Correct ? | 6 Yes | 1 No |
Answer / steve holton
Clarifications:
As noted, registers are part of the CPU, and --not-- part of
"memory".
There are 16 general purpose registers, which are numbered
0--15 (not 16 - that would be 17 registers!).
There are also other registers - control registers, PSW,
etc., that are used by the operating system, and "normal
mortals" are supposed to ignore...
Floating point registers are separate from the general
purpose registers. Not all floating point instructions
require even registers - if you use 128-bit ("extended
precision") floating point, you can use FPR registers
1,3,5,and 7-15 on ESA390 models that have the AFP registers
"installed".
| Is This Answer Correct ? | 3 Yes | 0 No |
about ICM instruction.
In the house keeping section of an MVS assembly language program, like the one below STM R14,R12,12(R13) BASR R12,R0 USING *,R12,R11 LA R11,2048 LA R11,2048(R11,R12) .... .... 1. What if BASR R12,R0 IS NOT PRECEDE USING *,R12,R11? 2. USING (base address), REGISTER does USING directive says assembler to treat particular Register as a base register with the mentioned base address..in the above case * i.e current location counter..well if that is the case why we need BASR R12,R0 ? 3. What if I write like STM R14,R12,12(R13) BASR R12,R0 LA R11,2048 LA R11,2048(R11,R12) USING *,R12,R11 there is no address resolution being calculated in both LA statements so is it a right way to set Base register?..will there be any issues with Domain regarding R11 and R12?
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