MICROPROCESSOR AND MICROCONTROLLER

Detailed explanation-1: -R13 is defined in the Thumb instruction set so that its use is primarily as a stack pointer. R13 is normally identified as Stack Pointer (SP) in Thumb instructions. In 32-bit Thumb instructions, if you use SP as a general purpose register beyond the architecturally defined constraints, the results are unpredictable.

Detailed explanation-2: -Stack registers in x86 In 8086, the main stack register is called stack pointer-SP. The stack segment register (SS) is usually used to store information about the memory segment that stores the call stack of currently executed program. SP points to current stack top.

Detailed explanation-3: -The stack pointer is a register that points to the top of the stack. In the ARM processor, there are no dedicated stack pointer registers, and any one of the general purpose registers can be used as the stack pointer.

Detailed explanation-4: -By convention, r13 is used as a stack pointer (sp) in ARM assembly language. The C and C++ compilers always use r13 as the stack pointer. In User mode, r14 is used as a link register (lr) to store the return address when a subroutine call is made.