The central processing unit (CPU) of a computer consists of an arithmetic logic unit (ALU) , a control unit (CU) and memory. When all these components can be organized on a single silicon chip by means of LSI, VLSI or ELSI technology, then such structure (chip) is called a microprocessor. It is able to perform its results by moving data around or by performing calculations. Such a device can fetch instructions from memory, decode and execute them, perform logical and arithmetic functions, accept data from input devices and send results to the output devices. The development of microprocessors is merely dependent on the development of integrated circuit technology. Starting from single scale integration (SSI) in early 1960s this fields of technology has sought changes at prodigious rate even the giga-scale integration (GSI)- a one billion component chip, at the eve of next millenium. A break through in the development of microprocessor was achieved in 1971, when Intel developed its first micro processors; Intel 4004. The 4004 was the first chip to cantains all of the components of a CPU on a single chip.The features of Intel 4004 are:
· It has capacity of handling of four bits at a time.
· There is specific instruction for reading keyboard and perfroming decimal and hexadecimal arithmetic.
· The fixed programs stored in read only memory and data stored in small read/write memories are used by Intel 4004.
· It is used in low cost configuration with keyboards and displays.
The next major step in the evolution of the microprocessors was the introduction of Intel 8008in 1972. It was the first 8 bit microprocessor designed by terminals. The salient features of Intel 8008 are:
· It can handle eight bits of data.
· It can access larger amounts of read/write memories (16k compared to 4k for 4004). The program can be placed in either type of memories.
· It can handle peripherals like printers and CRTs.
· It has an internal memory pointer.
· It can conveniently handle and process more data.
Some other examples of 8 bit microprocessors are Motorola 6500, Fair-child F - 8, Signetics 2650, Toshiba TLCS – 12, Texas instruments – 9900. The Intel 8080 was designed to be the CPU of a general purpose 8 bit microcomputer. Although 8080 is a 8 bit microprocessor, it is faster, has richer instruction set and has large addressing capability. At the end of 1970s the powerful, general purpose 16 bit microprocessors appeared. Intel 8086 is one of the popular 16 bit microprocessors. In 1985, Intel introduced its 32 bit microprocessors 80386. It is better to list the development of Intel processors, in the process of highlighting the evolution of the microprocessors.
8080: The world’s first general purpose microprocessor. This was an 8 bit machine, with an 8 bit data and 16 bit address path to memory.
8086: A far more powerful 16 bit machine with 1 MB memory capacity. In addition to wider data path and larger registers, it has a feature of instruction pipelining. For this purpose it consist of an instruction cache, that prefetches a few instructions before they are executed.
80286: This is an extension of 8086 with addressing capability of 16 MB of memory instead of just 1 MB.
80386: It is the Intel’s first 32 bit microprocessor. With a 32 bit architecture, the 80386 rivaled the complexity and power of mini computers and mainframes.
80486: The 80486 introduces the use of much more sophisticated and powerful cache technology and sophisticated instruction pipelining.
Pentium: With the Pentium, Intel introduces the use of superscalar techniques, which allow multiple instructions to execute in parallel.
In this growing electronics world non of the sector will be away from the use of microprocessors. However, its applications are generally it is categorized into following four groups- Test instruments, Communications, Computer and Indutries.
Test Instruments:
The microprocessor are widely used in signal generatora, oscilloscopes, counters, digital voltmeters, x-ray analyzers, blood group analyzers, baby incubator, frequency synthesizers, data acquisation systems, spectrum analyzers etc. For example: fluke 6010 a synthesized signal generator uses 4004 microprocessor.
Computer:
The microprocessor is a central processing unit (CPU) of the microcomputers. It can perform arithmetic and logic functions as well as control function. The control unit of microprocessor sends signals to input, output units, memory. ALU and arrange the sequenceof their controlling operation.
Industries:
The microprocessor is widely used in data monitoring systems, smart cameras for quality control, automatic weighting, batching systems, assembly machine control, torque certification systems, machine tool controllers, optical page readers, graphics and drafting system and automatic testers.
Today microprocessors are being used in every electrical and electronic machines.
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