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Instruction pre-fetching is very important phenomena in 8086 microprocessor. There is a 16-bit register set located in the BIU (bus Interface Unit) known as QUEUE.
While EU (Execution Unit) is working on the instructions i.e decoding and executing them, queue fetches the next sixinstruction byte of the running program. It is to be noted that, unlike stack (which is last in first out), queue is first in first out. Instruction which is fetched first is retrieved first.
This is much faster than sending out the address and waiting for memory to send back the instruction byte or bytes.
Limitation of QUEUE:
This pre-fetching of instruction speeds up processing but sometimes during 1JMP and CALL statements, queue has to be dumped and reloaded again starting from the next address.
Fetching the instruction while the current instruction executes is called pipelining.
1. Like in c++ programming, when a function is called the control is transferred to the function and its instruction
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Christopher Burdorf has written: 'Prefetching simulation objects in a persistent simulation environment' -- subject(s): Computer simulation
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instruction register is used to store the next instruction to be executed. instruction pointer is used to store the address of the next instruction to be executed.
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The word "instruction" can be a noun.
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what is supervision of instruction
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An absolute instruction is an assembly language instruction using only absolute addresses.
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