DIGITAL ELECTRONICS, DIGITAL ELECTRONICS, MICROPROCESSORS, MICROPROCESSORS, AND COMPUTERS AND COMPUTERS

By By

Naaimat MuhammedNaaimat Muhammed

IntroductionIntroduction

• The computer you are using to read this The computer you are using to read this page uses a microprocessor to do its work.page uses a microprocessor to do its work.

• The microprocessor is the heart of any The microprocessor is the heart of any normal computernormal computer . .

• The microprocessor you are using might be The microprocessor you are using might be a Pentium, a K6, a PowerPC, a Sparc or any a Pentium, a K6, a PowerPC, a Sparc or any of the many other brands and types of of the many other brands and types of microprocessors.microprocessors.

• The rate of growth of electronics, instrumentation, and The rate of growth of electronics, instrumentation, and microcomputer technology is nearly incomprehensible.microcomputer technology is nearly incomprehensible.

• Microcomputers or microprocessors are now found in Microcomputers or microprocessors are now found in most laboratory instruments, including even balances most laboratory instruments, including even balances and pH meters.and pH meters.

• Digital circuits offer some important advantages over Digital circuits offer some important advantages over their analog counterparts.their analog counterparts.

• Digital circuits are less susceptible to environmental Digital circuits are less susceptible to environmental noise.noise.

• Digitally encoded signals can be transmitted with a Digitally encoded signals can be transmitted with a higher degree of signal integrityhigher degree of signal integrity . .

• Digital signals may be transmitted directly to digital Digital signals may be transmitted directly to digital computers.computers.

Microprocessor HistoryMicroprocessor History

• A microprocessor -- also known as a CPU or central A microprocessor -- also known as a CPU or central processing unitprocessing unit . .

• It is a complete computation engine that is fabricated on a It is a complete computation engine that is fabricated on a single chipsingle chip . .

• The first microprocessor was the Intel 4004, introduced in The first microprocessor was the Intel 4004, introduced in 1971.1971.

• The 4004 was not very powerful -- all it could do was add The 4004 was not very powerful -- all it could do was add and subtract, and it could only do that 4 and subtract, and it could only do that 4 bitsbits at a time at a time . .

• The 4004 powered one of the first portable electronic The 4004 powered one of the first portable electronic calculators.calculators.

Intel 4004Intel 4004

Intel 8080Intel 8080

• The first microprocessor to The first microprocessor to make it into a home make it into a home computer was the Intel computer was the Intel 80808080

• Introduced in 1974 ,it was Introduced in 1974 ,it was a complete 8-bit computer a complete 8-bit computer on one chip. on one chip.

• The first microprocessor to The first microprocessor to make a real splash in the make a real splash in the market was the Intel market was the Intel

8088,which was8088,which was improvements on the basic improvements on the basic

design of the 8088design of the 8088..

Analog and Digital SignalsAnalog and Digital Signals

• Chemical signals are of two types, digital and analog.Chemical signals are of two types, digital and analog.

• An example of a digital, or discrete, chemical signal is the radiant An example of a digital, or discrete, chemical signal is the radiant

energy produced by the decay of a radioactive species.energy produced by the decay of a radioactive species. • The signal consists of a series of pulses of energy produced as The signal consists of a series of pulses of energy produced as

individuals atoms decay.individuals atoms decay.

• These pulses can be converted to electrical pulses and counted.These pulses can be converted to electrical pulses and counted. • The form that the signal takes depends on how one looks at the The form that the signal takes depends on how one looks at the

signal.signal.

• A properly designed detector can respond to the individual A properly designed detector can respond to the individual photons, producing a signal that consists of a series of pulses that photons, producing a signal that consists of a series of pulses that

can be measured.can be measured.

Arithmetic With Binary Arithmetic With Binary NumbersNumbers

• In typical digital measurement, a high-speed electronic In typical digital measurement, a high-speed electronic counter is used to count the number of pulses that occur counter is used to count the number of pulses that occur

within a specified set of boundary conditions.within a specified set of boundary conditions. • Examples of signals and boundary conditions include Examples of signals and boundary conditions include

number of photons or alpha decay particles emitted by an number of photons or alpha decay particles emitted by an analyte per second or the number of drops of titrant per analyte per second or the number of drops of titrant per

millimole of analyte.millimole of analyte. • Counting such signals electronically requires that they first Counting such signals electronically requires that they first

be transduced to provide a series of pulses of more or less be transduced to provide a series of pulses of more or less equal voltage.equal voltage.

• For this reason, electronic counting is performed by For this reason, electronic counting is performed by binary numbers; here, only two digits, 0 and 1, are binary numbers; here, only two digits, 0 and 1, are required to represent any number.required to represent any number.

MicroprocessorMicroprocessor

• The following The following diagram shows an diagram shows an extremely simple extremely simple microprocessor microprocessor capable of doing capable of doing those three things:those three things:

continuedcontinued

• This is about as simple as a microprocessor gets. This This is about as simple as a microprocessor gets. This microprocessor has:microprocessor has:

• An An address busaddress bus (that may be 8, 16 or 32 bits wide) that (that may be 8, 16 or 32 bits wide) that

sends an address to memorysends an address to memory • A A data busdata bus (that may be 8, 16 or 32 bits wide) that can (that may be 8, 16 or 32 bits wide) that can

send data to memory or receive data from memorysend data to memory or receive data from memory • An An RDRD (read) and (read) and WRWR (write) line to tell the memory (write) line to tell the memory

whether it wants to set or get the addressed locationwhether it wants to set or get the addressed location

• A A clock lineclock line that lets a clock pulse sequence the processor that lets a clock pulse sequence the processor • A A reset linereset line that resets the program counter to zero (or that resets the program counter to zero (or

whatever) and restarts executionwhatever) and restarts execution

Relationship Between Relationship Between Decimal and BinaryDecimal and Binary

• An instrument for counting the An instrument for counting the number of electrical pulses from number of electrical pulses from a transducer per unit time a transducer per unit time consists of the following consists of the following componentscomponents

Signal ShapersSignal Shapers

• This is essentially an This is essentially an operational amplifier operational amplifier that makes use of a that makes use of a voltage comparator to voltage comparator to convert the signal to convert the signal to the square wave formthe square wave form

Binary CounterBinary Counter

• Electronic counters employ a series of binary circuits( or Electronic counters employ a series of binary circuits( or

binaries) to electrical pulsesbinaries) to electrical pulses • These circuits are basically electronic switches that have These circuits are basically electronic switches that have

two logic states, on/l and off/0.two logic states, on/l and off/0. • Each binary circuit can the be used to represent one digit Each binary circuit can the be used to represent one digit

of a binary number(or the coefficient of a power of two) a of a binary number(or the coefficient of a power of two) a convenient binary circuits for counting is the so-called flip-convenient binary circuits for counting is the so-called flip-flop.flop.

Binary Coded Decimal Binary Coded Decimal SystemSystem

• This is the system that converts This is the system that converts from binary to decimal numbersfrom binary to decimal numbers

ScalersScalers

• The process of reducing a count by a known The process of reducing a count by a known fraction is called scaling, and becomes fraction is called scaling, and becomes important when the frequency of a signal is important when the frequency of a signal is greater than the counting device can greater than the counting device can accommodate.accommodate.

• In this situation, a scaler is introduced In this situation, a scaler is introduced

between the signal source and the counterbetween the signal source and the counter

ClocksClocks

• Many digital applications require a highly Many digital applications require a highly reproducible and accurately known reproducible and accurately known frequency source to be used in conjunction frequency source to be used in conjunction with the measurement of time.with the measurement of time.

• Generally, these frequency sources are Generally, these frequency sources are

based upon quartz crystalsbased upon quartz crystals..

Digital to Analog Digital to Analog ConvertersConverters • Digital signals are often Digital signals are often

converted to their converted to their analog counterparts for analog counterparts for the control of the control of instruments or for instruments or for display by readout display by readout devices such as meters devices such as meters and analog recordersand analog recorders

• One common method is One common method is to use a circuit similar to use a circuit similar to a summing circuit of to a summing circuit of an operational amplifieran operational amplifier

Microprocessors and Microprocessors and MicrocomputersMicrocomputers

• A microprocessor is a large-scale integrated circuit made A microprocessor is a large-scale integrated circuit made up of tens and even hundreds of thousands of transistors, up of tens and even hundreds of thousands of transistors, resistors, switches, and other circuit elements resistors, switches, and other circuit elements miniaturized to fit on a single silicon chip.miniaturized to fit on a single silicon chip.

• Microcomputers are finding an ever-increasing use in Microcomputers are finding an ever-increasing use in controlling analytical instruments and in processing, controlling analytical instruments and in processing,

storing, and displaying the data derived from them.storing, and displaying the data derived from them. • Automation leads to more rapid data acquisition, Automation leads to more rapid data acquisition,

which shortens the time required for analysis or which shortens the time required for analysis or increases precision by providing time for additional increases precision by providing time for additional replicate measurements to be made.replicate measurements to be made.

Applications of ComputersApplications of Computers

• Computer interactions with Computer interactions with analytical instruments are of two analytical instruments are of two types.types.

• Active ApplicationsActive Applications

• Passive ApplicationsPassive Applications

REFERENCES:REFERENCES:

• http://192.215.107.101/ebn/942/tech/http://192.215.107.101/ebn/942/tech/techfocus/1071main.htmltechfocus/1071main.html

• http://www.chem.usu.edu/~sbialk/http://www.chem.usu.edu/~sbialk/Classes/565/opamps/opamps.htmlClasses/565/opamps/opamps.html

• Skoog, Holler, and Neiman. Skoog, Holler, and Neiman. Principles Principles of Instrumental Analysisof Instrumental Analysis. 5th ed. . 5th ed. Orlando: Harcourt Brace & Co., 1998.Orlando: Harcourt Brace & Co., 1998.