The execution unit (EU) is supposed to decode or execute an instruction. When EU is busy in decoding and executing an instruction, the BIU fetches up to six instruction bytes for the next instructions. These bytes are called as the pre-fetched bytes and they are stored in a first in first out (FIFO) register set, which is called as a queue.
The fetching of opcodes well in advance, prior to their need for execution increases the overall efficiency of the processor boosting its speed. The processor no longer has to wait for the memory access operations for the subsequent instruction opcode to complete.
Instruction queue is 6 bytes so that it can store the longest instruction.
8086 is the Ist processor to support Instruction Queue.
The execution unit (EU) is supposed to decode or execute an instruction. When EU is busy in decoding and executing an instruction, the BIU fetches up to six instruction bytes for the next instructions. These bytes are called as the pre-fetched bytes and they are stored in a first in first out (FIFO) register set, which is called as a queue.
The fetching of opcodes well in advance, prior to their need for execution increases the overall efficiency of the processor boosting its speed. The processor no longer has to wait for the memory access operations for the subsequent instruction opcode to complete.
Instruction queue is 6 bytes so that it can store the longest instruction.
8086 is the Ist processor to support Instruction Queue.