Category talk:ARM Assembly: Difference between revisions

 

Consistent is that the programmer can see 16 registers numbered R0 to R15. R15 is the PC (Program Counter). There is not a RTS (Return from Subroutine) instruction, instead typically a MOVS PC, R14 (Acorn often used an ORRS PC, R14 etc instruction) is used to return to the calling point. NB R14 is the return address not R13 as stated in the text. R13 was usually assigned the meaning of a SP (Stack Pointer) but that was a convention recommended by Acorn rather than being a fundamental design of the microprocessor.