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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 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. By default, the stack grows downward in memory, so newer values are placed at lower memory addresses.
8 (includes program counter and stack pointer, though any register can act as stack pointer) Variable (16-, 32-, or 48-bit) Condition code Little Extended Instruction Set, Floating Instruction Set, Floating Point Processor, Commercial Instruction Set No No POWER, PowerPC, Power ISA: 32/64 (32→64) 3.1 [30] 1990 3 (mostly). FMA, LD/ST-Update
R7 is the program counter. Any register can be a stack pointer but R6 is used for hardware interrupts and traps. VAX [32] 16: The general purpose registers are used for floating-point values as well. Three of the registers have special uses: R12 (Argument Pointer), R13 (Frame Pointer), and R14 (Stack Pointer), while R15 refers to the Program ...
A pop or pull operation: a data item at the current location to which the stack pointer points is read, and the stack pointer is moved by a distance corresponding to the size of that data item. There are many variations on the basic principle of stack operations. Every stack has a fixed location in memory at which it begins.
However, such subroutines do not need to return that value to r14—they merely need to load that value into r15, the program counter, to return. The ARM calling convention mandates using a full-descending stack. In addition, the stack pointer must always be 4-byte aligned, and must always be 8-byte aligned at a function call with a public ...
Register R7 is the program counter (PC). Although any register can be used as a stack pointer, R6 is the stack pointer (SP) used for hardware interrupts and traps. R5 is often used to point to the current procedure call frame. To speed up context switching, some PDP-11 models provide dual R0-R5 register sets.
Since addressing modes 0-3 were identical, this made 13 (electronic) addressing modes, but as in the PDP-11, the use of the Stack Pointer (R14) and Program Counter (R15) created a total of over 15 conceptual addressing modes (with the assembler program translating the source code into the actual stack-pointer or program-counter based addressing ...