Tuesday, July 5, 2011

Winstar Cyber: How To Make Money Online Using Webaswers

Winstar Cyber: How To Make Money Online Using Webaswers: "Many people nowadays want to make money using the internet. Yes it is possible for you to make lots of money from the internet, but be warne..."
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How To Make Money Online Using Webaswers

Many people nowadays want to make money using the internet. Yes it is possible for you to make lots of money from the internet, but be warned, you have to work hard in order to earn. So there is no free money on the internet. Those who have worked hard are now enjoying the fruits of their hard earned money.

Webanswers is a good site that you can earn money from by answering and asking questions. Yes! You ask and answer questions and get paid. After answering questions, if they are okey they are awarded as the correct answers. Then advertisements are placed on that page that has got your answers and you earn revenue from the clicks.

It is easy to sign up with webanswers and start participating. To sign up for webanswers, you can click on this link.

You can check the FAQ for all the questions you have about webaswers and the steps to follow.
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Tuesday, June 7, 2011

Tribulations of Mark:- Part 1

Tribulations of Mark:- Part 1
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Saturday, April 30, 2011

The Computer Memory Explained

The Computer Memory

Computer Memory 
Fig 1. Computer Memory
Memory in computers is very important, but many people do not recognize the role it plays. Memory is the workspace for the computer’s processor. It is a temporary storage area where the programs and data being operated on by the processor must reside. Memory storage is considered temporary because the data and programs remain there only as long as the computer has electrical power or is not reset. Before being shut down or reset, any data that has been changed should be saved to a more permanent storage device (usually a hard disk) so that it can be reloaded into memory in the future. Failure to do this you will loose all your unsaved work.


Memory is often referred as RAM, short for Random Access Memory. Memory is called RAM because you can randomly (as opposed to sequentially) access any location in memory. Read-only memory (ROM), for example, is also randomly accessible, yet is usually differentiated from the system RAM because it maintains data without power and can’t normally be written to.

In computers, memory is generally divided into two:
  • Random Access Memory (RAM)
  • Read Only Memory (ROM)
Random Access Memory (RAM)
Computers and other electronic devices make use of RAM for temporally storage of data and programs in use. There are two different types of RAM, DRAM (Dynamic Random Access Memory) and SRAM (Static Random Access Memory).

DRAM
Dynamic RAM (DRAM) is the type of memory chip used for implementing most of the main memory in a modern PC. The memory cells in a DRAM chip make use of tiny capacitors that retain a charge to indicate a bit (1, or 0 depending on the charge). DRAMs use only one transistor and capacitor pair per bit, which makes them very dense, offering more memory capacity per chip than other types of memory.

Advantages
  • It is very dense, meaning you can pack a lot of bits into a very small chip
  • It is inexpensive, which makes purchasing large amounts of memory affordable.
Disadvantages
  • It is slow because it requires refreshing.
Examples of RAM types.
  1. Fast Page Mode DRAM (FPM DRAM)
  2. Burst Extended Data Out RAM (BEDO DRAM)
  3. Extended Data Out RAM (EDO DRAM)
  4. Synchronous DRAM (SDRAM)
  5. Double Data Rate DRAM (DDR SDRAM)
  6. Rambus DRAM (RDRAM)
SRAM
SRAM stands for static RAM, which is so named because it does not need the periodic refresh rates like DRAM. Because of how SRAMs are designed, not only are refresh rates unnecessary, but SRAM is much faster than DRAM and much more capable of keeping pace with modern processors. It is used to implement cache memories that need to transfer data at a very high speed.

An example of ROM
Fig 2. An example of ROM
Source: wikipedia

READ ONLY MEMORY (ROM)
This is the other type of memory used in computers. Read-only memory, or ROM, is a type of memory that can permanently or semi-permanently store data. It is called read-only because it is either impossible or difficult to write to. ROM also is often referred to as nonvolatile memory because any data stored in ROM remains there, even if the power is turned off. Thus, ROM is an ideal place to put the PC’s startup instructions—that is, the software that boots the system.

EPROM with a quartz window
Fig 3. EPROM with a quartz window

Examples of ROMs
Read Only Memory (ROM) – This is a type of ROM manufactured with the binary data (0s and 1s) already programmed or integrated into the die. The data can not be changed.
Programmable Read Only Memory (PROM) – A PROM is a type of ROM that is blank when new and that must be programmed with whatever data you want.
Erasable Programmable Read Only Memory (EPROM) –This is a type of ROM that is erasable. To erase the contents you subject it to a strong source of UV light which penetrates through the quartz window on the top. Then new data can be entered into it again.
Electrically Erasable Programmable Read Only Memory (EEPROM) – This type of ROM is also called flash PROM. It is a PROM whose data can be erased in situ using electricity, no special equipment is required.
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Tuesday, April 12, 2011

Wireless Network

In Computer networking, the wireless network makes use of the wireless media or the unbounded media to transfer signals (data) from one computer to another, or from one network to another. The wireless network is often an appropriate, and sometimes necessary, networking option because it eliminates the need for too much cabling.
Sometimes the wireless network will incorporate the use actual cables thus forming a kind of mixed component network called Hybrid Network.

Types of Wireless Networks

  1. Wireless PAN (Wireless Personal Area Networks)
  2. Wireless LAN (Wireless Local Area Network)
  3. Wireless WAN (Wireless Wide Area Network)
  4. Mobile devices networks

Capabilities of Wireless Networks.

Whenever you implement a wireless network, you can be able to achieve the following;
  • Provide temporary connections to an existing, cabled network.
  • Help provide backup to an existing network.
  • Provide some degree of portability.
  • Extend networks beyond the limits of physical connectivity.

Uses of Wireless Network

These are some of the areas where the wireless network can be used:-
  1. Busy areas, such as lobbies and reception areas.
  2. People who are constantly moving, such as doctors and nurses in hospitals.
  3. Isolated areas and buildings.
  4. Departments where physical settings changes frequently and unpredictably.
  5. Structures, such as historic buildings, for which cabling present challenges.

Wireless Communications with LANs

The use of an access point transceiver is one of several ways to achieve wireless networking. An access point is a stationary transceiver connected to the cable based LAN that enables the cordless PC to communicate with the network. The access point acts as a conduit for the wireless PC. The process is initiated when the wireless PC sends a signal to the access point; from there, the signal reaches the network. The truly wireless communication, therefore, is the communication from the wireless PC to the access point.

Wireless LANs use five techniques for transmitting data:

  1. Infrared transmission.
  2. Laser transmission.
  3. Narrowband (single-frequency) radio transmission.
  4. Spread-spectrum radio transmission.
  5.  Microwaves.
1. INFRARED: All infrared wireless networks operate by using an infrared light beam to carry the data between devices. These systems need to generate very strong signals because weak transmission signals are susceptible to interference from light sourcessuch as windows and the signal cannot travel through objects.
LEDs are used to transmit signals or data between devices and photoreceptor diodes are used to receive data on the other side. Infrared signals are in a very high frequency range hence they have a good thro’ put. Infrared is just below the visible range of light between 100 GHz and 1000 THz.
There are four types of infrared networks:
1.      Line-of-sight networks: - Data is transmitted only if the transmitter and the receiver have a clear line of sight between them.
2.      Scatter infrared networks: - As the name suggests, signals are scattered in all directions, the broadcasted signals bounce of walls and ceilings and eventually hit the receiver.
3.      Reflective networks: - Optical receiver situated near the computer transmits towards a common location which then direct transmission to the appropriate computer.
4.      Broadband optical telepoint: - This infrared wireless LAN provides broadband services and is capable of handling high-quality multimedia requirements that can match those provided by a cabled network.
 
 2. LASER: High-powered laser transmitters can transmit data for several thousand yards when line-of-sight communication is possible. Laser technology is similar to infrared technology in that it requires a direct line of sight, and any person or object that breaks the laser beam will block the transmission.

3. NARROWBAND (SINGLE-FREQUENCY) RADIO TRANSMISSION: This approach is similar to broadcasting from a radio station. The user tunes both the transmitter and the receiver to a certain frequency. This does not require line-of-sight focusing because the broadcast range is 3000 meters (9842 feet).

4. SPREAD-SPECTRUM RADIO TRANSMISSION: - Spread-spectrum radio broadcasts signals over a range of frequencies.The available frequencies are divided into channels, known as hops, which are comparable to one leg of a journey that includes intervening stops between the starting point and the destination.

The spread-spectrum adapters tune in to a specific hop for a predetermined length of time, after which they switch to a different hop. A hopping sequence determines the timing. The computers in the network are all synchronized to the hop timing. This type of signaling provides some built-in security in that the frequency-hopping algorithm of the network would have to be known in order to tap into the data stream.

5. MICROWAVES: - Microwave systems are a good choice for a wireless network and can interconnect buildings in small, short-distance systems such as those on a campus or in an industrial park.
Microwave transmission is currently the most widely used long-distance transmission method. It is excellent for communicating between two line-of-sight points such as:
  • Satellite-to-ground links.
  • Between two buildings.
  • Across large, flat, open areas, such as bodies of water or deserts.
A microwave system consists of the following:
  • Two radio transceivers: one to generate (transmitting station) and one to receive (receiving station) the broadcast.
  • Two directional antennas pointed at each other to implement communication of the signals broadcast by the transceivers. These antennas are often installed on towers to give them more range and to raise them above anything that might block their signals. (Move out or peer through the window and you will be able to see some).
satellite communication dish
satellite communication dish
Satellite
Satellite

Microwave communication falls into two categories:-
i.Terrestrial Microwave
ii.Satellite microwave.

i) TERRESTRIAL MICROWAVE: - It uses earth based transmitters and receivers in the low GHz range of frequency (4-6GHz or 21-23GHz). Speed is often 1-10Mbps. The signal is normally encrypted for privacy. Communication is through line of sight and cannot go round corners or through buildings. Line-of-sight means that the transmitter’s beam is focused directly on the receiver. Microwave dishes (parabolic antennas) are seen on top of tall buildings. 

ii) SATELLITE MICROWAVE: - It uses communication satellite that operates in geosynchronous orbit (rotate round the earth) at 22300 miles 36000km above the earth’s surface which is an altitude that will cause it to stay in a fixed position relative to the rotation of the earth. A geosynchronous satellite must orbit at 22,300 miles altitude and it must be over the earth’s equator.

Parabolic antennas are used to communicate with the satellite, and a transmission from earth’s station to the satellite is called an uplink while the transmission from the satellite to the earth station is called a downlink.
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