Search results
Results From The WOW.Com Content Network
The instruction cycle (also known as the fetch–decode–execute cycle, or simply the fetch–execute cycle) is the cycle that the central processing unit (CPU) follows from boot-up until the computer has shut down in order to process instructions. It is composed of three main stages: the fetch stage, the decode stage, and the execute stage.
In computer engineering, instruction pipelining is a technique for implementing instruction-level parallelism within a single processor. Pipelining attempts to keep every part of the processor busy with some instruction by dividing incoming instructions into a series of sequential steps (the eponymous "pipeline") performed by different processor units with different parts of instructions ...
Classic RISC pipelines avoided these hazards by replicating hardware. In particular, branch instructions could have used the ALU to compute the target address of the branch. If the ALU were used in the decode stage for that purpose, an ALU instruction followed by a branch would have seen both instructions attempt to use the ALU simultaneously.
Modern processors can even do some of the steps out of order as decoding on several instructions is done in parallel. Decoding the op-code in the instruction register includes determining the instruction, determining where its operands are in memory, retrieving the operands from memory, allocating processor resources to execute the command (in ...
C = A+B needs four instructions. 3-operand, allowing better reuse of data: [11] CISC — It becomes either a single instruction: add a,b,c. C = A+B needs one instruction. CISC — Or, on machines limited to two memory operands per instruction, move a,reg1; add reg1,b,c; C = A+B needs two instructions.
Instruction or instructions may refer to: A specific direction or order given to someone to perform a task or carry out a procedure. They provide clear guidance on how to achieve a desired outcome. They can be written or verbal, and they typically include detailed steps or actions to follow.
The focus on "reduced instructions" led to the resulting machine being called a "reduced instruction set computer" (RISC). The goal was to make instructions so simple that they could easily be pipelined, in order to achieve a single clock throughput at high frequencies. This contrasted with CISC designs whose "crucial arithmetic operations and ...
Instructions are patterns of bits, digits, or characters that correspond to machine commands. Thus, the instruction set is specific to a class of processors using (mostly) the same architecture . Successor or derivative processor designs often include instructions of a predecessor and may add new additional instructions.