Instruction queue is the sequence of processing and giving chance to execute the instruction.
We can simply say that instruction queue is the fetching of the instruction opcodes from program memory well in advance is known as prefetching and it is served by using prefetch input queue.
The pre-fetched instructions are stored in data structure – namely a queue.
The 8088 microprocessor has instruction queue is 4 byte (four byte). Where as the 8086 has 6 byte instruction queue.