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The program counter (PC), [1] commonly called the instruction pointer (IP) in Intel x86 and Itanium microprocessors, and sometimes called the instruction address register (IAR), [2] [1] the instruction counter, [3] or just part of the instruction sequencer, [4] is a processor register that indicates where a computer is in its program sequence.
In the x86 assembly language, the JMP instruction performs an unconditional jump. Such an instruction transfers the flow of execution by changing the program counter.There are a number of different opcodes that perform a jump; depending on whether the processor is in real mode or protected mode, and an override instruction is used, the instructions may take 16-bit, 32-bit, or segment:offset ...
The "PC Word" register is split in half; the right 18 bits contains the program counter and the left 13 bits contains the processor status flags, with five zeros between the two sections. The condition register bits, which record the results of arithmetic operations ( e.g. overflow), can be accessed by only a few instructions.
In the center of the room, there is a work area containing a simple two function (addition and subtraction) calculator known as the Accumulator and a resettable counter known as the Program Counter. The Program Counter holds the address of the next instruction the Little Man will carry out. This Program Counter is normally incremented by 1 ...
The program counter (PC) is a register that holds the memory address of the next instruction to be executed. After each instruction copy to the memory address register (MAR), the PC can either increment the pointer to the next sequential instruction, jump to a specified pointer, or branch conditionally to a specified pointer. [2]
r15 is the program counter, and not usable as a general purpose register; r13 is the stack pointer; r8–r13 can be switched out for others (banked) on a processor mode switch. Older versions had 26-bit addressing, [35] and used upper bits of the program counter (r15) for status flags, making that register 32-bit. ARM 32-bit (Thumb) 8: 16
program counter; subroutine return address; processor status (servicing an interrupt, running in protected mode, etc.) condition codes (result of previous comparisons) Because special registers are closely tied to some special function or status of the microcontroller, they might not be directly writeable by normal instructions (such as adds ...
The program counter is loaded from the ABORT vector (see tables). As the address pushed to the stack is that of the aborted instruction rather than the contents of the program counter, executing an RTI ( R e T urn from I nterrupt) following an ABORT interrupt will cause the processor to return to the aborted instruction, rather than the next ...