Search results
Results From The WOW.Com Content Network
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 ...
In computer engineering, Halt and Catch Fire, known by the assembly language mnemonic HCF, is an idiom referring to a computer machine code instruction that causes the computer's central processing unit (CPU) to cease meaningful operation, typically requiring a restart of the computer.
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 ...
ENIAC used ten-position ring counters to store digits; each digit required 36 vacuum tubes, 10 of which were the dual triodes making up the flip-flops of the ring counter. Arithmetic was performed by "counting" pulses with the ring counters and generating carry pulses if the counter "wrapped around", the idea being to electronically emulate the ...
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.
The program counter is typically set to a hard coded value when the CPU is first powered on, and will hence execute whatever machine code happens to be at this address. Similarly, the program counter can be set to execute whatever machine code is at some arbitrary address, even if this is not valid machine code. This will typically trigger an ...
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]