Question

How many registers are there in ARM CPU for programmer to use?

Which registers can you use for general computation?

Which register are special purpose, and cannot be used for general computation?

What is the size, i.e. number of bits, each of these general purpose registers can hold?

Which are most useful flags in the current program status register?

Answer 1

How many registers are there in ARM CPU for programmer to use?

Ans:Total 16 register are there in ARM CPU for programmer to use .

which are as follows r0, r1, r2 , r3 , r4 , r5 , r6 , r7 , r8 , r9 , r10 , r11 , r12 , r13 , r14 , r15

Which registers can you use for general computation?

Ans: Register r13(stack pointer) and r14(link register) can be used for general computation.

Which register are special purpose, and cannot be used for general computation?

Ans:Register r15(program counter )  is a special purpose register contains the address of the next instruction to be fetched by the processor ,cannot  used for general computation.

What is the size, i.e. number of bits, each of these general purpose registers can hold?

Ans : 32 bit size

Which are most useful flags in the current program status register?

Ans :Most useful flags in the current program status resister are -

Negative flag (N) : Indicates that a value is negative.
Zero flag (Z): Zero flag is  set when an instruction produces a zero result.
Carry flag(C) : It indicate "borrows" and carry also from previous operation.
Overflow flag(V) : This flag is set if an instruction produces a result that overflows ..