History of Microprocessor

First Microprocessor: ##Intel 4004 (1971)

• A 4-bit microprocessor with 4 KB memory
• Instruction set contained only 45 instructions
• Fabricated with P-channel MOSFET technology
• Allowed to execute instructions at the slow rate of 50 KIPS.

i.e. KIPS means Kilo-instructions per second. ##Intel 8008

• A 8-bit microprocessor with 16kbyte memory
• Instruction set contained a total of 48 instructions
• Execution time is about 20us

Second Microprocessor: ##Intel 8080 (1973)

• First computer was developed by this microprocessor
• A 8-bit microprocessor with 64 Kbyte memory
• Ten times faster then 8008 microprocessor
• Made by TTL circuit

##Intel 8085 (1977)

• A 8-bit microprocessor
• Has 8-bit data bus/16-bit address bus
• Has internal clock generator, internal system controller
• Execution time is about 103 us

i.e. Memory calculation performed by address bus.

INITIAL COMMERTIAL PHASE (1946-1968)

After the end of 2nd world war, mobile services become commercially available. In 1949 the FCC officially recognized mobile radio as a new class of service.In 1946, interconnection of mobile users to the public telephone network was also introduced to allow calls from fixed phones to the mobile users. This systems used three channels at 150MHz using FM. A single powerful transmitter provided coverage to an area of 50 miles from the base stations. This system was introduced by American telephone & telegraph company ( AT&T)

PIONEER PHASE (1921-1947)

First experiments were carried out in Detroit in 1920s. One way broadcasts were made to receivers in mobile police cars. In 1928 a student of Purdue University was able to develop superhetrodyne receiver that operated successfully in mobile environment. In 1930s mobile transmitters were developed and first two way mobile system was placed in operation by NewJersy police department. up to early 1930s all mobile radio systems in operation used amplitude modulation. At the end of 1930s two way FM mobile system was implemented and was proved to be much more resistant to propagation problems in mobile environment.

MICROPROCESSOR

Microprocessor: The heart of the microprocessor based digital computer is an IC. Microprocessor is a controlling element. It controls the memory and input/output devices through bios and transfer instructions and data between microprocessor and memory, I/O devices. Main task of microprocessor:

• Data transfer between microprocessor and memory; I/O devices.
• Simple arithmetic & logic operation.
• Program flow via simple decisions.

Micro controller: The micro controllers on a single chip which typically includes a microprocessor , 64 byte of R/W memory (RAM), 1-2 KB ROM and several signal lines. Example: ZlongZ8, IntelMCSS1, Motorola 68HC11 etc. Bus:

1. Control bus (Unidirectional)
2. Data bus (Bidirectional)
3. Address bus (Unidirectional)

i.e

• Read operation means import data to microprocessor.
• Write operation means export data from microprocessor.

BASICS ON MICROPROCESSOR

Programming Language: A set of instructions written in a computer language is called programming language & the languages used are called programming language।

programming languages are two types:

• Low level language
• High level language (machine independent)

Low level language two types.

• machine language
• assembly language

Compiler: It converts high level language to machine language (all at the same time). Interpreter: It converts one after another. Assembler: Assembler is a computer program softwer that translate assembly language program from mnemonic codes to the binery machine code of computer. i.e. The assembler allowed the programmer to use mnemonic codes, such as ADD for addition, in place of a binery number such as 01000111.

DC MOTORS

Introduction: As a DC motor is operated by DC current, it is called DC motor. But a DC motor is ideally an AC motor.Because of the commutator changes the direction of the current, it is theoretically an AC motor. All electric motors of the world are originally AC motors. Speed Control: Speed of DC motor can be controlled by two methods.

• Shunt field control.
• Armature voltage control.

Shunt Field Control: The speed of DC motor increase with decrease of flux. So shunt field excitation can be decreased to increase the speed of motor.This phenomenon is applied to control the speed of DC motors ( i.e armature current must be constant to apply this method) .Like most of other types of motors the output torque is inversely proportional to the speed.

The range of speed variation is ruled by some factors. To increase the speed we have to decrease the shunt field excitation, but because of residual flux the flux intensity will never be zero. Again to decrease the speed the excitation must be increased, but after a limit it causes over heating.

Armature Voltage Control: In this method the armature voltage is varied to control the speed. The torque developed by a DC motor is the difference between the power developed by the applied current and the power developed by the back EMF in the armature. As the shunt field excitation is constant the torque is constant over a wide range of speed for rated current in the armature.

DOUBLE ENTRY SYSTEM

Definition: Double entry system is a process of recording where every transaction is analyzed by duel aspect and every davit entry is balanced by a equal credit entry. Features:

• Two aspects
• Business entity
• Scientific System of Accounting
• Complete System of Accounting
• Accurate Accounting system
• Receivable and Payable of same amount of money

Advantage:

• proper and complete account is kept
• Arithmetical accuracy of the books is verified
• Ascertainment of profit and loss
• Real financial condition can find out
• Expenses can be controlled

Disadvantages:

• Enough time labor and money need
• To record account need qualified person
• Limited application

Rules of Determination of debit & credit:

• Traditional method
• Equation method

Traditional Method

• Assets : If asset is bought ------- Dr.
• A/C : If asset is sold ---------- Cr.
• Nominal A/C : Expenses & loss of business ---- Dr.
• Nominal A/C : Income & profit of business ---- Cr.

Equation Method Assets = Liabilities + Owners equity Here it has been treated that owner is separate from his business. So the capital which the owner paid has been treated as liabilities and is investment to the owner. Here liabilities is external liabilities. O.E is internal liabilities. O.E is affected by profit & loss. so the equation can be expended as follow: A = L + [ O.E + ( R - E ) ] => A + E = L + O.E + R For this method=>

• Asset A/C : If asset increase ------ Dr.
• Asset A/C : If asset decrease ------Cr.
• Liabilities A/C : If liabilities increase ------Cr.
• Liabilities A/C : If liabilities decrease ------Dr.
• Owners equity A/C : If owners equity increase ------ Cr.
• Owners equity A/C : If owners equity decrease ------Dr.
• Income A/C : If income increase ------Cr.
• Income A/C : If income decrease ------ Dr.
• Expense A/C : If expense increase ------ Dr.
• Expense A/C : If expense decrease ------ Cr.

POWER SUPPLY

TRANSFORMER LESS POWER SUPPLY For most of the DC power supply system transformer is very popular because of high current capacity, but it is inductive.If we can use a single capacitor instead of the transformer with high voltage rating it also possible to make a power supply system.It will improve the power factor and it is less expensive. Let start from a very simple circuit containing a capacitor and a resistor.If 330uF capacitor( bipolar ) is in series with a 2.4 ohms resistor and the voltage source of 220v ac, 50Hz is used then we get 12 volts across the resistor,but the current is about 5A.This current leads the voltage by about 87 degree. So in spite of high current drawing from the main negligible power loss through the capacitor, but it drops about 2o8 volts. The main disadvantage of this process is the load have to draw always 5A current, if it changed the voltage also changed across the load. i.e here the load is assumed to be fully resistive. More information will be published in this blog with circuit diagrams. submitted by Sajib, email-sajib.b04@gmail.com.

SEISMIC CONFIGURATION OF BUILDINGS

Now-a-days building design considering earth quake effect is a most important feature in civil engineering .Some important simple feature are discussed here which reduce earth quake risk . 1) While a plan is prepared for proposed building, structural safety safety should keep in mind. 2) Building having shape H,L,T,Y,U are much susceptible to earth quake collapse. 3) Building having regular shape i.e nearly square or rectangular have much resistance to earth quake. 4) There should be equilibrium in both plan and elevation. 5)Building having excessive length to breadth ratio should have expansion joints. 6)If height to breadth ratio is greater than 4, three dimensional analysis is required. 7)Set-back or reducing dimension of sides should be avoided. 8) Provision of shear walls are required at proper location to strengthen structure against earth quake. 9) Structures having parking on ground floor or basement require special design of column . If required concrete wall should provide surrounding columns. 10) Strength of column should be at least 20% greater than that of beam. 11) For complex structural plan three dimensional earth quake analysis is required. 12) Five inch brick wall is not safe requiring lintel in all location.

LIQUEFACTION DURING EARTH-QUAKE

Definition: Losing of shear strength due to oscillatory motion is known as liquefaction of sand. Susceptible Soils: Soil most susceptible to liquefaction is saturated fine and medium sand of uniform particle size.

Effect of liquefaction: Structure resting on such soil sinks into soil. In case of partial liquefaction the structure may undergo excessive settlement and the complete failure may not occur.

Critical void ratio: The void ratio at which with an increase in strain void ratio does not change is known as critical void ratio.

If a sand initially is at critical void ratio, there will be practically no change in volume with increase in shear strain.

Mechanism of Liquefaction: When such sand deposit classified above, have a void ratio greater then critical void ratio and subjected to sudden shearing stress, these decrease in volume and pore pressure u' increases. The soil momentarily liquefies and behaves as dense fluid.

Precaution: Extreme care should be taken while constructing a structure on such a soils. If the deposit are compacted to void ratio smaller then critical void ratio, the chances of liquefaction are reduced.