Microprocessor and Positive and Negative Logic

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Chapter-1
Introduction
A microprocessor is a computer processor which incorporates the functions of a computer's central
processing unit (CPU) on a single integrated circuit (IC).
The microprocessor, also known as the Central Processing Unit (CPU), is the brain of all computers
and many household and electronic devices. Multiple microprocessors, working together, are the
"hearts" of Datacentres, Supercomputers, communications products, and other digital devices.
A few of the applications using microprocessors:
 Business applications such as Desktop Publishing
 Industrial applications such as Power Plant control
 Measuring instruments such as multi meter
 Household equipment such as washing machine
 Medical equipments such as blood pressure monitor
 Defence equipmenmts such as Light Combat aircraft
Fig.1.Microprocessor Chip

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Chapter-2
Evolution of Microprocessor
4-bit Microprocessor: Intel 4004
 Introduced in 1971.
 It was the first microprocessor by Intel.
 Ran at a clock speed of 108 KHz.
 It had 2,300 transistors.
 Maximum addressable memory was only 640 bytes.
Fig.2.1: Intel 4004
 It was first 8-bit μP.
 Originally ran at a clock speed of 200 KHz (0.2MHz). .
 Maximum addressable memory was upto 16 kb
Fig.2.2: Intel 8008

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Intel 8080
 It was also 8-bit μP.
 Its clock speed was 2 MHz
 It could address up to 64KB of memory.
Fig.2.3: Intel 8080
Z-80 processor
 It introduced in 1976
 It could run all 8080 programs.
 Initially the clock speed 2.5MHz (later versions ran up to 10MHz)
 It had 8,500 transistors
 It could access 64KB of memory
Fig.2.4: Z-80
Intel 8085
 Its clock speed was 5 MHz.
 Its data bus is 8-bit.
 It could access 64 KB of memory.
Fig.2.5: Intel 8085

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MOS Technology 6502
 It was introduced in 1976
 It was an 8-bit processor like 8080
 Its clock speed was 1-2 MHz
Fig.2.6: MOS Technology 6502
 Introduced in 1978
 Its clock speed is 4.77 MHz, 8 MHz and 10 MHz, depending on the version.
 Its data bus is 16-bit
 It could access 1 MB of memory.
 It had 29,000 instructions.
Fig.2.7: Intel 8086
Intel 8088
 It was created as a cheaper version of Intel’s 8086.
 It was a 16-bit processor with an 8-bit external bus.
Fig.2.8: Intel 8088

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 It was first 32-bit μP.
 Its data bus is 32-bit and address bus is 32-bit.
 It could address 4 GB of memory.
 It had 2,75,000 transistors.
 Its clock speed varied from 16 MHz to 33 MHz depending upon the various versions.
 Different versions:
 80386 DX
 80386 SX
 80386 SL
 Intel 80386 became the best-selling microprocessor in history
Fig.2.9: Intel 80386
Intel 80486
 It had 1.2 million transistors.
 Its clock speed varied from 16 MHz to 100 MHz depending upon the various
versions.
 It had five different versions:
 80486 DX
 80486 SX
 80486 DX2
 80486 SL
 80486 DX4
 8 KB of cache memory was introduced.
Fig.2.10: Intel 80486

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Intel Pentium
 It was originally named 80586.
 Its clock speed was 66 MHz.
 Its data bus is 32-bit and address bus is 32-bit.
 It could address 4 GB of memory.
 It could execute 110 million instructions per second.
 Cache memory:
 8 KB for instructions.
 8 KB for data.
19
Fig.2.11: Intel Pentium
Intel Pentium Pro
 It had 21 million transistors.
 It was primarily used in server systems.
 Cache memory:
 8 KB for instructions.
 8 KB for data.
 It had L2 cache of 256 KB
Fig.2.12: Intel Pentium Pro

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Intel Pentium II
 Its clock speed was 233 MHz to 500 MHz.
 It could execute 333 million instructions per second.
 MMX technology was supported.
 L2 cache & processor were on one circuit
Fig.2.13: Intel Pentium II
64-bit microprocessor:
Intel Core 2
 It is a 64-bit μP.
 Its clock speed is from 1.2 GHz to 3 GHz.
 It has 291 million transistors.
 It has 64 KB of L1 cache per core and 4 MB of L2 cache.
 It is launched in three different versions:
 Intel Core 2 Duo
 Intel Core 2 Quad
 Intel Core 2 Extreme
Fig.2.14: Intel Core 2

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Intel Core i5
 It has 4 physical cores.
 Its clock speed is from 2.40 GHz to 3.60 GHz.
 It has 64 KB of L1 cache per core, 256 KB of L2 cache and 8 MB of L3 cache. 30
Fig.2.15: Intel Core i5
Intel Core i3
Intel Core i7

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Chapter 3
Classification of Microprocessors
Classification on the basis of Hardware and architecture:
RISC Processor: RISC stands for Reduced Instruction Set Computer. It is designed to reduce
the execution time by simplifying the instruction set of the computer. Using RISC processors, each
instruction requires only one clock cycle to execute results in uniform execution time.
Examples-
 Power PC: 601, 604, 615, 620
 DEC Alpha: 210642, 211066, 21068, 21164
 MIPS: TS (R10000) RISC Processor
 PA-RISC: HP 7100LC
SISC Processor: CISC stands for Complex Instruction Set Computer. It is designed to
minimize the number of instructions per program, ignoring the number of cycles per instruction.
The emphasis is on building complex instructions directly into the hardware.
The compiler has to do very little work to translate a high-level language into assembly level
language/machine code because the length of the code is relatively short, so very little RAM is
required to store the instructions.
Examples-
 IBM 370/168
 VAX 11/780
 Intel 80486

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Special Processor: These are the processors which are designed for some special purposes.
Few of the special processors are briefly discussed –
Coprocessor: A coprocessor is a specially designed microprocessor, which can handle its particular
function many times faster than the ordinary microprocessor.
For example − Math Coprocessor.
Input/output Processor: It is a specially designed microprocessor having a local memory of its
own, which is used to control I/O devices with minimum CPU involvement.
For example −
 DMA (direct Memory Access) controller
 Keyboard/mouse controller
Transputer (Transistor Computer): A transputer is a specially designed microprocessor with its
own local memory and having links to connect one transputer to another transputer for inter-
processor communications.
DSP (Digital Signal Processor): This processor is specially designed to process the analog signals
into a digital form. This is done by sampling the voltage level at regular time intervals and
converting the voltage at that instant into a digital form. This process is performed by a circuit
called an analogue to digital converter, A to D converter or ADC.

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Chapter-4
Integrated Circuits
An integrated circuit (IC), sometimes called a chip or microchip, is a semiconductor wafer on which
thousands or millions of tiny resistors, capacitors, and transistors are fabricated. An IC can function
as an amplifier, oscillator, timer, counter, computer memory, or microprocessor. A particular IC is
categorized as either linear analog or digital, depending on its intended application.
Fig.4.1: Integrated Circuits Chip

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Chapter-5
History of Integrated Circuits
Integrated circuits developed from transistor technology as scientists sought ways to build more
transistors into a circuit. The first integrated circuits were patented in 1959 by two Americans-Jack
Kilby, an engineer, and Robert Noyce, a physicist-who worked independently. Integrated circuits
had caused a great revolution in electronics in the 1960's as transistors had caused in 1950's. The
circuits were first used in military equipment and space craft and helped make possible the first
human space flights of the 1960's.
Fig.5: Jack Kilby's original integrated circuit
Most integrated circuits are small pieces, or “chips,” of silicon, perhaps (0.08 to 0.15 sq in) long, in
which transistors are fabricated. Photolithography enables the designer to create tens of thousands
of transistors on a single chip by proper placement of the many n-type and p-type regions. These are
interconnected with very small conducting paths during fabrication to produce complex special-
purpose circuits. Such integrated circuits are called monolithic because they are fabricated on a
single crystal of silicon. Chips require much less space and power and are cheaper to manufacture
than an equivalent circuit built by employing individual transistors. Integrated circuits (ICs) make
the microcomputer possible; without them, individual circuits and their components would take up
far too much space for a compact computer design.

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Advantage of Integrated Circuits:
The major advantages of integrated circuits over those made by interconnecting discrete
components are as follows:
 Extremely small size – Thousands times smaller than discrete circuits. It is because
of fabrication of various circuit elements in a single chip of semiconductor material.
 Very small weight owing to miniaturised circuit.
 Very low cost because of simultaneous production of hundreds of similar circuits on
a small semiconductor wafer. Owing to mass production of an IC costs as much as
an individual transistor.
 More reliable because of elimination of soldered joints and need for fewer
interconnections.
 Lower power consumption because of their smaller size.
 Easy replacement as it is more economical to replace them than to repair them.
 Increased operating speed because of absence of parasitic capacitance effect.
 Close matching of components and temperature coefficients because of bulk
production in batches.
 Improved functional performance as more complex circuits can be fabricated for
achieving better characteristics.
 Greater ability of operating at extreme temperatures.
Disadvantages of Integrated circuits:
The major disadvantages of integrated circuits over those made by interconnecting discrete
components are as follows:
 Limited power rating as it is not possible to manufacture high power (say greater
than 10 W) ICs.
 Need of connecting inductors and transformers exterior to the semiconductor chip as
it is not possible to fabricate inductor and transformers on the semiconductor chip
surface.
 Operation at low voltage as ICs function at fairly low voltage.
 Quite delicate in handling as these cannot withstand rough handling or excessive
heat.
 Need of connecting capacitor exterior to the semiconductor chip as it is neither
convenient nor economical to fabricate capacitances exceeding 30pF. Therefore, for
higher values of capacitance, discrete components exterior to IC chip are connected.
 High grade P-N-P assembly is not possible.
 Low temperature coefficient is difficult to be achieved.
 Large value of saturation resistance of transistors.
 Voltage dependence of resistor and capacitors.

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Classification of ICs (Integrated Circuits)
Below is the classification of different types of ICs basis on their chip size. SSI-Small Scale
Integration.
 SSI: Small scale integration. 3 – 30 gates per chip.
 MSI: Medium scale integration. 30 – 300 gates per chip.
 LSI: Large scale integration. 300 – 3,000 gates per chip.
 VLSI: Very large scale integration. More than 3,000 gates per chip.

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Chapter-6
Digital Logic Families
A logic family of monolithic digital integrated circuit devices is a group of electronic logic gates
constructed using one of several different designs, usually with compatible logic levels and power
supply characteristics within a family.
Logic Families indicate the type of logic circuit used in the IC.
The main types of logic families are:
 TTL(Transistor Transistor Logic)
 CMOS (Complementary MOS)
 ECL (Emitter Coupled Logic)
 MOS(Metal-Oxide Semiconductor)
Transistor Transistor Logic (TTL)
Transistor–transistor logic (TTL) is a class of digital circuits built from bipolar junction
transistors (BJTs) and resistors. It is called transistor–transistor logic because transistors
perform both the logic function (e.g., AND) and the amplifying function (compare with
resistor–transistor logic (RTL) and diode–transistor logic (DTL)).
Fig.6.1.Diagram of TTL

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Complementary MOS (CMOS)
CMOS (complementary metal-oxide semiconductor) is the semiconductor technology used
in the transistors that are manufactured into most of today's computer microchips.
Fig.6.2.Diagram of CMOS
Emitter Coupled Logic (ECL)
In electronics, emitter-coupled logic (ECL) is a high-speed integrated circuit bipolar
transistor logic family. ECL uses an overdriven BJT differential amplifier with single-ended
input and limited emitter current to avoid the saturated (fully on) region of operation and its
slow turn-off behavior.
Fig.6.3.Diagram of ECL

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Metal-Oxide Semiconductor (MOS)
It is a three-layer sandwich of a metal, an insulator (usually an oxide of the substrate), and a
Semiconductor substrate, used in integrated circuits.
Fig.6.4.Diagram of MOS

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Chapter-7
Positive and Negative Logic
The binary signal at the input and the output of any gate has one of the two values, except during
the transition one signal value represents logic 1 (one) and other logic 0 (zero), depending upon the
positive and negative logic the higher signal level ‘H’ and lower signal level ‘L’ differs.
The table below shows the two assignments that define positive and negative logic systems.
Positive Logic Negative Logic
H = 1 H = 0
L = 0 L = 1
A logical operation has two different implementations depending on if positive or negative logic is
used:
Fig.7.1.Diagram of Positive and Negative logic
Fig.7.2.Truth table of Positive and Negative Logic

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Chapter-8
Characteristics of Logic Families
The main characteristics of Logic families include:-
 Fan-Out
 Power Dissipation
 Propagation Delay
 Noise Margin
Fan-Out:- It specifies the number of standard loads that the output of the gate can drive without
impairment of its normal operation.
Power Dissipation: - It refers the power consume by the gate which must be available from the
power supply.
Propagation delay: -It is the average transition delay time for the signal to propagate from input to
output when the signals change in value.
Noise Margin: - It refers the limit of the noise voltage which may be present without impairing the
proper operation of the circuit.

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REFERENCES
1. http://electriciantraining.tpub.com/14185/css/Positive-And-Negative-Logic-85.htm
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3. http://whatis.techtarget.com/definition/integrated-circuit-IC
4. http://www.electrical4u.com/integrated-circuits-types-of-ic/
5. https://en.wikipedia.org/wiki/Microprocessor
6. http://sce2.umkc.edu/csee/hieberm/281_new/lectures/basic-electrical-components/pos-neg-
logic.html
7. http://webcache.googleusercontent.com/search?q=cache:http://scanftree.com/microprocessor
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9. http://electronicspost.com/advantages-and-disadvantages-of-integrated-circuits-ics/
10. http://www.electricaltechnology.org/2015/04/types-of-ics-classification-of-integrated-
circuits-and-their-limitation.html
11. https://en.wikipedia.org/wiki/Transistor-transistor_logic
12. https://en.wikipedia.org/wiki/CMOS
13. M. Morris Mano, Digital logic and Computer Design.

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