MICROPROCESSORMICROPROCESSORDEFINITIONDEFINITIONA microprocessor is a tiny piece of silicon with millions of microscopicInterconnected transistors etched onto it. This circuitry is divided intosections with specific functions, which together perform the task of mostelectronic devices –from calculators to cell phones to supercomputer.While there are different types of microprocessors, they all share someBasic principles and functions.
HistoryHistoryThe first commercial mc was the INTEL 4004 which appeared inThe first commercial mc was the INTEL 4004 which appeared in1971. It was originally designed for use in a calculator. The1971. It was originally designed for use in a calculator. The4004 is referred to as 4-bit mc since it processed only 4 bit of4004 is referred to as 4-bit mc since it processed only 4 bit ofdata at time and was used in calculators.data at time and was used in calculators.as integrated densities increased with the rapidas integrated densities increased with the rapiddevelopment of integrated circuit manufacturing technology, thedevelopment of integrated circuit manufacturing technology, thepower and performance of mc also increased. This is reflectedpower and performance of mc also increased. This is reflectedin the increase in the CPU word size to 4,8,16 and by midin the increase in the CPU word size to 4,8,16 and by mid1980s,32 bits.1980s,32 bits.The INTEL 4004 was followed with ,among other theThe INTEL 4004 was followed with ,among other the4040,8008,8080,8086,80186,80286,80386,486and Pentium.4040,8008,8080,8086,80186,80286,80386,486and Pentium.
Internal StructureInternal StructureThe CPU is divided into two parts BIU and EU ,that speed upthe processing.
Bus interface unitBus interface unit► It sends out addresses ,fetch instruction from memory,It sends out addresses ,fetch instruction from memory,reads data from memory & write data to port and memory.reads data from memory & write data to port and memory.It handles all transfer of data & addresses on the bus forIt handles all transfer of data & addresses on the bus forexecution unit.execution unit.Execution unitTells the BIU where to fetch instructions orData from, decode instructions & execute instructions.
Components of structureComponents of structure► BUSBUS:-various i/o devices & memory devices are connected:-various i/o devices & memory devices are connectedto CPU by buses.to CPU by buses.► Address busAddress bus :-carries the add of memory location or i/o:-carries the add of memory location or i/odevices the CPU want to access.devices the CPU want to access.► Data busData bus:- used to carry transform data b/w processor ,:- used to carry transform data b/w processor ,memory and i/o.memory and i/o.► Control busControl bus:- carries signals for various operations.:- carries signals for various operations.► flag register(16-bit)flag register(16-bit):-:- iindicate some conditions produced byndicate some conditions produced bythe execution of an instructions or control some operationsthe execution of an instructions or control some operationsof EUof EU..► RegisterRegister:-:-these can be used individually to store 8-bitthese can be used individually to store 8-bitdata. These are the temporary storage of data & accesseddata. These are the temporary storage of data & accessedquickly.quickly.
►QueueQueue :- contains the next instructions for:- contains the next instructions forCPU.CPU.►Stack pointerStack pointer:- 16-bit register that hold the:- 16-bit register that hold theaddress of stacktop.address of stacktop.
componentscomponentsThe L2/L3 Cache provides a large capacity(1MB-4MB) for storing the data on-chip. It isslower than the Data Cache and Instruction Cacheand takes about 10-25 cycles to access. It isprobed when the requested data is not present inthe Instruction Cache or the Data Cache.The Instruction Cache is a small storagestructure ( 32KB) that can be accessed quickly(typically in 1-2 processor cycles). Instructionsfrom the program are temporarily stored in theInstruction Cache. This reduces the likelihood ofgetting instructions from other on-chip storage orfrom outside the chip, which typically stops theprocessor for tens or hundreds of cycles.
Data cache & register fileData cache & register fileThe Data Cache is a temporary storage for input data.The Data Cache is typically small (32KB) and can beaccessed quickly (in 2-3 processor cycles). If the requesteddata is not available in the Data Cache, the data issearched in other larger on-chip structures or main memorywhich typically incurs a delay of tens to hundreds ofprocessor cycles. The Data Cache also provides a faststorage for writing the output data generated from theprocessor.The Register File is a fast storage (1-2 cycles) thatis very small (32B-128B). the Register File is a partof the Instruction Set Architecture (ISA) defining themath and logic instructions usable by the software andimplemented by the hardware. The Register File is managedentirely by the software, and the requested data is guaranteedto be present in the Register File. The registers in a RegisterFile are used for data elements that are used very frequently .
Instruction fetch & decode unitInstruction fetch & decode unitThe Instruction Fetch unit probes theInstruction Cache and obtains the next instructionto be executed.The Decode Unit parses the instructions from theInstruction Fetch into three fields: The operation to beexecuted (e.g. ADD, BRANCH); the location of theinput data (e.g. register or memory); and thedestination of the output data. The Decode Unitproduces the control signals for other stages of themicroprocessor so that they can perform the operationrequested by the particular instruction
Read operand/ ALU /FloatingRead operand/ ALU /Floatingpoint unitpoint unitThe Read Operands unit reads the input data on which theoperation is to be performed. The operands may be located inthe register file or memory. If the operand is located in memory,the read unit requests the data from the Data Cache. If therequested data is not present in the data cache, the ReadOperands delays the instruction until all the input operands areavailable.The Arithmetic Logic Unit (ALU) performs the simplearithmetic and logic operations on the operands from the readstage.The Floating Point Unit (FPU) handles arithmetic operations onhigh-precision numbers. It also performs more advanced arithmeticoperations such as square root, trigonometry and logarithms. Theoutput of the ALU and FPU is written to the Register File or theData Cache
ConclusionConclusionAt end we can say that theAt end we can say that themicroprocessor Is the heart andmicroprocessor Is the heart andbrain of a system that control allbrain of a system that control allmajor operations of the system.major operations of the system.