High Quality Content by WIKIPEDIA articles! Fetching the instruction opcodes from program memory well in advance is known as prefetching and it is served by using prefetch input queue (PIQ).The pre-fetched instructions are stored in data structure Queue. The fetching of opcodes well in advance, prior to their need for execution increases the overall efficiency of the processor boosting it`s speed. The processor no longer has to wait for the memory access operations for the subsequent instruction opcode to complete. This architecture was prominently used in the Intel 8086 microprocessor.