CHAPTER :1
Q1. Give the full form of :-
URL (ii) FTP
(iii) ISP (iv) WWW
(v) HTTP (vi) ARPANET
(vii) TCP (viii) IP
(ix) MODEM (x) ISDN
(xi) IIS (xii) HTML
DNS
Q2. What is web server?
Q3. Name any three ISPs in India.
Q4. How do you differentiate between a web address and an e-mail address.
Q5. Write any two web extensions used with web addresses?
Q6. What is the purpose of using a web browser?
Q7. What is hypertext?
Q8. What are the advantages of the internet?
Q9. What are the two types of Modem?
Q10. What is a protocol?
Q11. How is information transferred on internet? / How the internet works?
Q12. What is ISP?
Q13. What is the most important feature of a website.
Q14. What do you mean by publishing a web page?
Q15. Give few examples of Letter Addressing System?
Q16. Explain the Letter Addressing System.
Q17. Explain the Number Addressing System.
Q18. Define the structure of a URL.
Q19. Name the first graphical web browser?
Q20. How the web works?
Q21. What is the web extension of :-
(i) edu (ii) com (iii) org (iv) gov (v) net
(vi) ca (vii) jp (viii) in (ix) uk
Friday, December 19, 2008
Sunday, July 13, 2008
RESISTOR
A resistor is a two-terminal electronic component that opposes an electric current by producing a voltage drop between its terminals in proportion to the current, that is, in accordance with Ohm's law: V = IR. The electrical resistance R is equal to the voltage drop V across the resistor divided by the current I through the resistor. Resistors are used as part of electrical networks and electronic circuits.
Identifying resistors
Most axial resistors use a pattern of colored stripes to indicate resistance. Surface-mount resistors are marked numerically. Cases are usually tan, brown, blue, or green, though other colors are occasionally found such as dark red or dark grey.
One can also use a multimeter or ohmmeter to test the values of a resistor
Four-band axial resistors
Main article: Electronic color code
Four-band identification is the most commonly used color coding scheme on all resistors. It consists of four colored bands that are painted around the body of the resistor. The first two numbers are the first two significant digits of the resistance value, the third is a multiplier, and the fourth is the tolerance of the value.
For example, green-blue-yellow-red is 56 x (10^4) Ω = 560 kΩ ± 2%).
Each color corresponds to a certain number, shown in the chart below. The tolerance for a 4-band resistor will be 1%, 5%, or 10%.
Color 1st band 2nd band 3rd band(multiplier) 4th band(tolerance)
Black 0 0 × 100
Brown 1 1 × 101 ±1%
Red 2 2 × 102 ±2%
Orange 3 3 × 103
Yellow 4 4 × 104
Green 5 5 × 105 ±0.5%
Blue 6 6 × 106 ±0.25%
Violet 7 7 × 107 ±0.1%
Gray 8 8 × 108 ±0.05%
White 9 9 × 109
Gold × 10-1 ±5%
Silver × 10-2 ±10%
None ±20%
Wednesday, July 9, 2008
Microcontroller
A microcontroller (also MCU or µC) is a computer-on-a-chip, containing a processor, memory, and input/output functions. It is a microprocessor emphasizing high integration, in contrast to a general-purpose microprocessor (the kind used in a PC). In addition to the usual arithmetic and logic elements of a general purpose microprocessor, the microcontroller integrates additional elements such as read-write memory for data storage, read-only memory for program storage, EEPROM for permanent data storage, peripheral devices, and input/output interfaces. At clock speeds of as little as a few MHz or even lower, microcontrollers often operate at very low speed compared to modern day microprocessors, but this is adequate for typical applications. They consume relatively little power (milliwatts), and will generally have the ability to sleep while waiting for an interesting peripheral event such as a button press to wake them up again to do something. Power consumption while sleeping may be just nanowatts, making them ideal for low power and long lasting battery applications.
Microcontrollers are frequently used in automatically controlled products and devices, such as automobile engine control systems, remote controls, office machines, appliances, power tools, and toys. By reducing the size, cost, and power consumption compared to a design using a separate microprocessor, memory, and input/output devices, microcontrollers make it economical to electronically control many more processes.
[edit] Platforms from Parallax, Inc.
Parallax produce the BASIC Stamp. These are Microchip PIC microcontrollers programmed with an interpreter that processes a program stored in an external EEPROM. Several different modules are available of varying processing speeds, RAM, and EEPROM sizes. The BASIC Stamp is used by Parallax as a platform for introductory programming and robotic kits.
The Parallax SX line of microcontrollers, formerly made by Ubicom, are 8-bit RISC microcontrollers (using a 12-bit instruction word) which have an unusually high speed, up to 75 MHz (75 MIPS), and a high degree of flexibility. They include up to 4096 12-bit words of Flash memory and up to 262 bytes of random access memory, an eight bit counter and other support logic. They are especially geared toward the emulation of I/O hardware in software, which makes them very flexible. SX-Key is Parallax's development tool for the SX line, supporting every SX chip commercially available. Using free SX-Key software (Assembly language), or the SX/B Compiler (BASIC-style language) from Parallax, the SX-Key programming tool can program SX chips in-system and perform in-circuit source-level debugging.
The Propeller is a multi-core microcontroller developed by Parallax, Inc. The currently released version features eight 32 bit cores, each operating independently at 80MHz, and 32 I/O pins. Most instructions require 4 clock cycles, so each core runs at 20 MIPS. Hub instructions, used to access the 8192 32 bit words of system memory and to communicate between cores, require between 7 and 22 clock cycles. There are also 512 32 bit words of memory on each core, which can be used to avoid using the slower system memory instructions. It can be programmed both in assembly language and a custom interpreted language named SPIN.
The BASIC Stamp is a microcontroller with a small, specialized BASIC interpreter (PBASIC) built into ROM. It is made by Parallax, Inc. and has been quite popular with electronics hobbyists since the early 1990s due to its low threshold of learning and ease of use (due to its simple BASIC language).
Although the BASIC Stamp has the form of a DIP chip, it is in fact a small Printed Circuit Board that contains the essential elements of a microprocessor system:
A Microcontroller containing the CPU, a built in ROM containing the BASIC interpreter, and various peripherals
Memory (a serial EEPROM)
A clock
A power supply
External input and output
PBASIC, the BASIC Stamp language, incorporates common microcontroller functions, including PWM, serial communications, I²C and 1-Wire communications, communications with common LCD driver circuits, hobby servo pulse trains, pseudo-sine wave frequencies, and the ability to time an RC circuit which may be used to detect an analog value.
The end result is that a hobbyist can connect a 9V battery to a BASIC Stamp and have a complete system. A connection to a PC allows the programmer to download software to the BASIC Stamp, which is stored in the onboard memory device. This memory stays programmed until it is erased and reprogrammed (the memory remains intact even when the power is removed).
There are currently four variants of the interpreter, BASIC Stamp 1, BASIC Stamp 2, the Javelin Stamp and the Spin Stamp. The Basic Stamp 2 variant has seven sub-variants:
BS1
BS2
BS2e
BS2sx
BS2p24
BS2p40
BS2pe
BS2px
These sub-variants feature more memory, faster execution speed, additional specialized PBASIC commands, extra I/O pins, etc, in comparison to the original BS2 model. While the BS1 and BS2 use a PIC, the remaining BASIC Stamp 2 variants use an SX processor.
The third variant is the Javelin Stamp. This module uses Sun Microsystems' Java programming language instead of Parallax's PBASIC.
The fourth variant is the Spin Stamp. The module is based on the Parallax Propeller and therefore uses the SPIN programming language instead of PBASIC.
Many companies now make virtual "clones" of the BASIC Stamp with additional features, such as faster execution, Analog-to-digital converters and hardware based PWM which can run in the background. However, many use the same pin out as the BASIC Stamp, to allow BASIC Stamp users to plug in their products in a design that already uses the BASIC Stamp
Microcontrollers are frequently used in automatically controlled products and devices, such as automobile engine control systems, remote controls, office machines, appliances, power tools, and toys. By reducing the size, cost, and power consumption compared to a design using a separate microprocessor, memory, and input/output devices, microcontrollers make it economical to electronically control many more processes.
[edit] Platforms from Parallax, Inc.
Parallax produce the BASIC Stamp. These are Microchip PIC microcontrollers programmed with an interpreter that processes a program stored in an external EEPROM. Several different modules are available of varying processing speeds, RAM, and EEPROM sizes. The BASIC Stamp is used by Parallax as a platform for introductory programming and robotic kits.
The Parallax SX line of microcontrollers, formerly made by Ubicom, are 8-bit RISC microcontrollers (using a 12-bit instruction word) which have an unusually high speed, up to 75 MHz (75 MIPS), and a high degree of flexibility. They include up to 4096 12-bit words of Flash memory and up to 262 bytes of random access memory, an eight bit counter and other support logic. They are especially geared toward the emulation of I/O hardware in software, which makes them very flexible. SX-Key is Parallax's development tool for the SX line, supporting every SX chip commercially available. Using free SX-Key software (Assembly language), or the SX/B Compiler (BASIC-style language) from Parallax, the SX-Key programming tool can program SX chips in-system and perform in-circuit source-level debugging.
The Propeller is a multi-core microcontroller developed by Parallax, Inc. The currently released version features eight 32 bit cores, each operating independently at 80MHz, and 32 I/O pins. Most instructions require 4 clock cycles, so each core runs at 20 MIPS. Hub instructions, used to access the 8192 32 bit words of system memory and to communicate between cores, require between 7 and 22 clock cycles. There are also 512 32 bit words of memory on each core, which can be used to avoid using the slower system memory instructions. It can be programmed both in assembly language and a custom interpreted language named SPIN.
The BASIC Stamp is a microcontroller with a small, specialized BASIC interpreter (PBASIC) built into ROM. It is made by Parallax, Inc. and has been quite popular with electronics hobbyists since the early 1990s due to its low threshold of learning and ease of use (due to its simple BASIC language).
Although the BASIC Stamp has the form of a DIP chip, it is in fact a small Printed Circuit Board that contains the essential elements of a microprocessor system:
A Microcontroller containing the CPU, a built in ROM containing the BASIC interpreter, and various peripherals
Memory (a serial EEPROM)
A clock
A power supply
External input and output
PBASIC, the BASIC Stamp language, incorporates common microcontroller functions, including PWM, serial communications, I²C and 1-Wire communications, communications with common LCD driver circuits, hobby servo pulse trains, pseudo-sine wave frequencies, and the ability to time an RC circuit which may be used to detect an analog value.
The end result is that a hobbyist can connect a 9V battery to a BASIC Stamp and have a complete system. A connection to a PC allows the programmer to download software to the BASIC Stamp, which is stored in the onboard memory device. This memory stays programmed until it is erased and reprogrammed (the memory remains intact even when the power is removed).
There are currently four variants of the interpreter, BASIC Stamp 1, BASIC Stamp 2, the Javelin Stamp and the Spin Stamp. The Basic Stamp 2 variant has seven sub-variants:
BS1
BS2
BS2e
BS2sx
BS2p24
BS2p40
BS2pe
BS2px
These sub-variants feature more memory, faster execution speed, additional specialized PBASIC commands, extra I/O pins, etc, in comparison to the original BS2 model. While the BS1 and BS2 use a PIC, the remaining BASIC Stamp 2 variants use an SX processor.
The third variant is the Javelin Stamp. This module uses Sun Microsystems' Java programming language instead of Parallax's PBASIC.
The fourth variant is the Spin Stamp. The module is based on the Parallax Propeller and therefore uses the SPIN programming language instead of PBASIC.
Many companies now make virtual "clones" of the BASIC Stamp with additional features, such as faster execution, Analog-to-digital converters and hardware based PWM which can run in the background. However, many use the same pin out as the BASIC Stamp, to allow BASIC Stamp users to plug in their products in a design that already uses the BASIC Stamp
Sunday, July 6, 2008
Servo Motors
Whats a Servo?
A Servo is a small device that has an output shaft. This shaft can be positioned to specific angular positions by sending the servo a coded signal. As long as the coded signal exists on the input line, the servo will maintain the angular position of the shaft. As the coded signal changes, the angular position of the shaft changes. In practice, servos are used in radio controlled airplanes to position control surfaces like the elevators and rudders. They are also used in radio controlled cars, puppets, and of course, robots.
(Click on picture for larger view)
A Futaba S-148 Servo
Servos are extremely useful in robotics. The motors are small, as you can see by the picture above, have built in control circuitry, and are extremely powerful for thier size. A standard servo such as the Futaba S-148 has 42 oz/inches of torque, which is pretty strong for its size. It also draws power proportional to the mechanical load. A lightly loaded servo, therefore, doesn't consume much energy. The guts of a servo motor are shown in the picture below. You can see the control circuitry, the motor, a set of gears, and the case. You can also see the 3 wires that connect to the outside world. One is for power (+5volts), ground, and the white wire is the control wire.
(Click on picture for larger view)
A servo disassembled.
So, how does a servo work? The servo motor has some control circuits and a potentiometer (a variable resistor, aka pot) that is connected to the output shaft. In the picture above, the pot can be seen on the right side of the circuit board. This pot allows the control circuitry to monitor the current angle of the servo motor. If the shaft is at the correct angle, then the motor shuts off. If the circuit finds that the angle is not correct, it will turn the motor the correct direction until the angle is correct. The output shaft of the servo is capable of travelling somewhere around 180 degrees. Usually, its somewhere in the 210 degree range, but it varies by manufacturer. A normal servo is used to control an angular motion of between 0 and 180 degrees. A normal servo is mechanically not capable of turning any farther due to a mechanical stop built on to the main output gear.
The amount of power applied to the motor is proportional to the distance it needs to travel. So, if the shaft needs to turn a large distance, the motor will run at full speed. If it needs to turn only a small amount, the motor will run at a slower speed. This is called proportional control.
How do you communicate the angle at which the servo should turn? The control wire is used to communicate the angle. The angle is determined by the duration of a pulse that is applied to the control wire. This is called Pulse Coded Modulation. The servo expects to see a pulse every 20 milliseconds (.02 seconds). The length of the pulse will determine how far the motor turns. A 1.5 millisecond pulse, for example, will make the motor turn to the 90 degree position (often called the neutral position). If the pulse is shorter than 1.5 ms, then the motor will turn the shaft to closer to 0 degress. If the pulse is longer than 1.5ms, the shaft turns closer to 180 degress.
As you can see in the picture, the duration of the pulse dictates the angle of the output shaft (shown as the green circle with the arrow). Note that the times here are illustrative, and the actual timings depend on the motor manufacturer. The principle, however, is the same.
A Servo is a small device that has an output shaft. This shaft can be positioned to specific angular positions by sending the servo a coded signal. As long as the coded signal exists on the input line, the servo will maintain the angular position of the shaft. As the coded signal changes, the angular position of the shaft changes. In practice, servos are used in radio controlled airplanes to position control surfaces like the elevators and rudders. They are also used in radio controlled cars, puppets, and of course, robots.
(Click on picture for larger view)
A Futaba S-148 Servo
Servos are extremely useful in robotics. The motors are small, as you can see by the picture above, have built in control circuitry, and are extremely powerful for thier size. A standard servo such as the Futaba S-148 has 42 oz/inches of torque, which is pretty strong for its size. It also draws power proportional to the mechanical load. A lightly loaded servo, therefore, doesn't consume much energy. The guts of a servo motor are shown in the picture below. You can see the control circuitry, the motor, a set of gears, and the case. You can also see the 3 wires that connect to the outside world. One is for power (+5volts), ground, and the white wire is the control wire.
(Click on picture for larger view)
A servo disassembled.
So, how does a servo work? The servo motor has some control circuits and a potentiometer (a variable resistor, aka pot) that is connected to the output shaft. In the picture above, the pot can be seen on the right side of the circuit board. This pot allows the control circuitry to monitor the current angle of the servo motor. If the shaft is at the correct angle, then the motor shuts off. If the circuit finds that the angle is not correct, it will turn the motor the correct direction until the angle is correct. The output shaft of the servo is capable of travelling somewhere around 180 degrees. Usually, its somewhere in the 210 degree range, but it varies by manufacturer. A normal servo is used to control an angular motion of between 0 and 180 degrees. A normal servo is mechanically not capable of turning any farther due to a mechanical stop built on to the main output gear.
The amount of power applied to the motor is proportional to the distance it needs to travel. So, if the shaft needs to turn a large distance, the motor will run at full speed. If it needs to turn only a small amount, the motor will run at a slower speed. This is called proportional control.
How do you communicate the angle at which the servo should turn? The control wire is used to communicate the angle. The angle is determined by the duration of a pulse that is applied to the control wire. This is called Pulse Coded Modulation. The servo expects to see a pulse every 20 milliseconds (.02 seconds). The length of the pulse will determine how far the motor turns. A 1.5 millisecond pulse, for example, will make the motor turn to the 90 degree position (often called the neutral position). If the pulse is shorter than 1.5 ms, then the motor will turn the shaft to closer to 0 degress. If the pulse is longer than 1.5ms, the shaft turns closer to 180 degress.
As you can see in the picture, the duration of the pulse dictates the angle of the output shaft (shown as the green circle with the arrow). Note that the times here are illustrative, and the actual timings depend on the motor manufacturer. The principle, however, is the same.
Wednesday, July 2, 2008
Friday, May 9, 2008
Sunday, March 23, 2008
WHAT IS ROBOTICS
Robotics is the science and technology of ROBOTS, their design, manufacture, and application. Robotics requires a working knowledge of electronics, mechanics and software, and is usually accompanied by a large working knowledge of many subjects. A person working in the field is a robocist.
A robot is a mechanical or virtual, artificial agent. It is usually an electromechanical system, which, by its appearance or movements, conveys a sense that it has intent or agency of its own. The word robot can refer to both physical robots and virtual software agents, but the latter are usually referred to as bots to differentiate.
A robot is a mechanical or virtual, artificial agent. It is usually an electromechanical system, which, by its appearance or movements, conveys a sense that it has intent or agency of its own. The word robot can refer to both physical robots and virtual software agents, but the latter are usually referred to as bots to differentiate.
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