MICROPROCESSORS

INTRODUCTION:

Microprocessors are regarded as one of the most important devices in our everyday machines called computers. Microprocessor is an electronic circuit that functions as the central processing unit (CPU) of a computer, providing computational control.

Typical microprocessors incorporate arithmetic and logic functional units as well as the associated control logic, instruction processing circuitry, and a portion of the memory hierarchy. Portions of the interface logic for the input/output (I/O) and memory subsystems may also be infused, allowing cheaper overall systems. While many microprocessors and single chip designs, some high-performance designs rely on a few chips to provide multiple functional units and relatively large caches. When combined with other integrated circuits that provide storage for data and programs, often on a single semiconductor base to form a chip, the microprocessor becomes the heart of a small computer, or microcomputer.

CLASSIFICATION:

Microprocessors are classified

1.     by the semiconductor technology of their design as:

·        TTL(transistor-transistor logic)

·         CMOS( complementary-metal-oxide semiconductor)

·        ECL(emitter-coupled logic)

2.     by the width of the data format they process as:

·        4-bit

·        8-bit

·        16-bit

·        32-bit

·        64-bit

3.     by their instruction set

·        CISC(complex instruction- set computer)

·        RISC(reduced instruction-set computer)

TTL technology is most commonly used, while CMOS is favored for portable computers and other battery-powered devices because of its low power consumption. ECL is used where the need for its greater speed offsets the fact that it consumes the most power.

Four-bit devices, while inexpensive, are good only for simple control applications; in general, the wider the data format, the faster and more expensive the device.

CISC processors, which have 70 to several hundred instructions, are easier to program than RISC processors, but are slower and more expensive.

Microprocessors have been described in many different ways. They have been compared with the brain and the heart of humans. Their operation has been likened to a switched board, and to the nervous system in an animal. They have often been called microcomputers. The original purpose of the microprocessor was to control memory. That is what they were originally designed to do, and that is what they do today. Specifically, a microprocessor is “a component that implements memory.”

HISTORY:

The first digital computers were built in the 1940’s using bulky relay and vacuum-tube switches. Relays had mechanical speed limitations. Vacuum tubes required considerable power, dissipated a significant amount of heat, and suffered high failure rates. Some systems achieved processing rates up to 1,000 operations per second. In 1947, Bell Laboratories invented the transistor, which rapidly replaced the vacuum tube as a computer switch for several reasons, including smaller size, faster switching speeds, lower power consumption and dissipation, and higher reliability. In the 1960sTexas Instruments invented the integrated circuit, allowing a single silicon chip to contain several transistors as well as their interconnections.

Intel 4004

      Year of Introduction 1971

•      4-bit Microprocessor

•      4 KB main memory

•      45 instructions

•      PMOS technology

•      Was first programmable device which was used in calculator.

Intel 8008

      Year of Introduction 1972

•      8-bit version of 4004

•      16 KB main memory

•      48 instructions

•      PMOS technology

Slow.

Intel 8080

      Year of Introduction 1973

•      8-bit microprocessor

•      64 KB main memory

•      2 microsecond clock cycle time.

•      5,00,000 instructions/sec.

•      30X faster than 8008.

•      NMOS technology

•      Drawback was that it need three power supply

•      Small computers (Micro Computer) were designed in mid 1970’s using 8080 as CPU.

Intel 8085

      Year of Introduction 1975

•      8-bit microprocessor-upgraded version of 8080.

•      64 KB main memory

•      1.3 microsecond clock cycle time.

•      246 instructions/sec.

•      Intel sold 100 millions copies of this 8-bit microprocessor.

Use only one key power supply

Intel 8086/8088

      Year of Introduction 1978 for 8086

•      16-bit microprocessor.

•      Data bus width of 8086 is 16 bit and 8 bit for 8088.

•      1 MB main memory

•      400 nanosecond clock cycle time.

•      6 byte instruction cache for 8086 and 4 byte for 8088.

•      246 instructions/sec.

•      Other improvement included more register and additional instruction.

•      In 1981 Intel decided to use 8088 in its personal computer.

Intel 80186

      Year of Introduction 1982

•      16-bit microprocessor upgraded version of 8086.

•      1 MB main memory

•      Contained special hardware like programmable counter, interrupted controller etc.

•      Never used in PC.

•      But was ideal for system that requires a minimum of hardware.

Intel 80286

  Year of Introduction 1983

•      16-bit high performance with memory management and protection.

•      16 MB main memory

•      Instruction execution time is as little as 250 ns.

•      Concentrate on features needed to implement MULTITASKING.

Intel 80386

      Year of Introduction 1986

•      Intel’s first practical 32 bit microprocessor.

•      4 GB main memory

•      Improvement includes page handling in virtual environment.

•      Includes hardware circuitry for memory management and memory assignment.

•      Memory paging and enhance I/O permission.

Intel 80486

      Year of Introduction 1989

•      32 bit high performance microprocessor.

•      4 GB main memory

•      Incorporates 80387-like floating point coprocessor.

•      8 KB cache on one package.

•      About half of the instructions executed in 1 clock instead of 2 on the 80386.

Pentium

      Year of Introduction 1993

•      32 bit microprocessor, 64 bit data-bus and 32 bit address bus.

•      4 GB main memory

•      Double clock 120 and 133 MHz versions.

•      Fastest version is the 233 MHz, Dual integer processor.

•      16 KB L1 cache (split instruction and data 8 KB each).

Pentium II Xeon

      Year of Introduction 1997

•      32 bit microprocessor, 64 bit data bus and 36 bit address bus MMX.

•      64 GB main memory,.

•      32 KB split instruction/data L1 cache (16 KB each).

•      Module integrated 512 KB L2 cache (133 MHz).

•      A version of P2 called Xeon; specifically designed for high end application.

Pentium III

      Year of Introduction 1999

•      32 bit microprocessor, 64 bit data bus and 36 bit address bus .

•      64 GB main memory,.

•      Dual independent Bus (Simultaneous L2 and system memory access.)

•      On chip 256 KB L2 cache

•      P2 was available in clock frequencies of up to 1 GHz.

Celeron (1999)

Continuing Intel's strategy of developing processors for specific market segments, the Intel Celeron processor is designed for the value PC market segment. It provides consumers great performance at an exceptional value, and it delivers excellent performance for uses such as gaming and educational software

Pentium III (1999)

The Pentium III processor features 70 new instructions. It was designed to significantly enhance Internet experiences, allowing users to do such things as browse through realistic online museums and stores and download high-quality video. The processor incorporates 9.5 million transistors, and was introduced using 0.25-micron technology.

Pentium III Xeon (1999)

The Pentium III Xeon processor extends Intel's offerings to the workstation and server market segments, providing additional performance for e-Commerce applications and advanced business computing. The processors incorporate the Pentium III processor's 70 SIMD instructions, which enhance multimedia and streaming video applications. The Pentium III Xeon processor's advance cache technology speeds information from the system bus to the processor, significantly boosting performance. It is designed for systems with multiprocessor configurations.

           Pentium IV

      Year of Introduction 2002

•      32 bit microprocessor, 64 bit data bus and 36 bit address bus.

•      64 GB main memory,

•      L4 to L9 GHz and the latest at 3.20 GHz (Hyper-Threading).

•      1 MB/512 KB/256 KB l2 Cache.

•      Specialized for streaming video, game and DVD applications

APPLICATION:

·     Microprocessor based systems are used in instructions, automatic testing product, speed control of motors, traffic light control, and light control of furnaces etc. it is very useful in the field of instrumentation. Frequency counters, function generators, frequency synthesizers, spectrum analyses and many other instruments are available, when microprocessors are used as controller. It is also used in medical instrumentation.

·      Microprocessor based controllers are available in home appliances, such as microwave oven, washing machine etc., microprocessors are being used in controlling various parameters like speed, pressure, temperature etc. These are used with the help of suitable transduction

·        Microprocessors are being used in a wide range of communication equipments. In telephone industry, these are used in digital telephone sets. Telephone exchanges and modem etc. The use of microprocessor in television, satellite communication have made teleconferencing possible. Railway reservation and air reservation system also uses this technology. LAN and WAN for communication of vertical information through computer network. 

·        Microprocessor based micro computer with software packages has changed the office environment. Microprocessors based systems are being used for word processing, spread sheet operations, storage etc. The microprocessor has revolutionized the publication technology.