Selasa, 13 Januari 2009
Senin, 05 Januari 2009
About RAM
VIRTUAL MEMORY
Virtual memory is a common part of most operating systems on desktop computers. It has become so common because it provides a big benefit for users at a very low cost.
Most computers today have something like 64 or 128 megabytes of RAM (random-access memory) available for use by the CPU (central processing unit). Often, that amount of RAM is not enough to run all of the programs that most users expect to run at once. For example, if you load the Windows operating system, an e-mail program, a Web browser and word processor into RAM simultaneously, 64 megabytes is not enough to hold it all. If there were no such thing as virtual memory, your computer would have to say, "Sorry, you cannot load any more applications. Please close an application to load a new one." With virtual memory, the computer can look for areas of RAM that have not been used recently and copy them onto the hard disk. This frees up space in RAM to load the new application. Because it does this automatically, you don't even know it is happening, and it makes your computer feel like is has unlimited RAM space even though it has only 32 megabytes installed. Because hard-disk space is so much cheaper than RAM chips, virtual memory also provides a nice economic benefit.
The area of the hard disk that stores the RAM image is called a page file. It holds pages of RAM on the hard disk, and the operating system moves data back and forth between the page file and RAM. (On a Windows machine, page files have a .SWP extension.)
Of course, the read/write speed of a hard drive is much slower than RAM, and the technology of a hard drive is not geared toward accessing small pieces of data at a time. If your system has to rely too heavily on virtual memory, you will notice a significant performance drop. The key is to have enough RAM to handle everything you tend to work on simultaneously. Then, the only time you "feel" the slowness of virtual memory is in the slight pause that occurs when you change tasks. When you have enough RAM for your needs, virtual memory works beautifully. When you don't, the operating system has to constantly swap information back and forth between RAM and the hard disk. This is called thrashing, and it can make your computer feel incredibly slow.
Random access memory (RAM) is the best known form of computer memory. RAM is considered "random access" because you can access any memory cell directly if you know the row and column that intersect at that cell.
The opposite of RAM is serial access memory (SAM). SAM stores data as a series of memory cells that can only be accessed sequentially (like a cassette tape). If the data is not in the current location, each memory cell is checked until the needed data is found. SAM works very well for memory buffers, where the data is normally stored in the order in which it will be used (a good example is the texture buffer memory on a video card). RAM data, on the other hand, can be accessed in any order.
Similar to a microprocessor, a memory chip is an integrated circuit (IC) made of millions of transistors and capacitors. In the most common form of computer memory, dynamic random access memory (DRAM), a transistor and a capacitor are paired to create a memory cell, which represents a single bit of data. The capacitor holds the bit of information -- a 0 or a 1 (see How Bits and Bytes Work for information on bits). The transistor acts as a switch that lets the control circuitry on the memory chip read the capacitor or change its state.
A capacitor is like a small bucket that is able to store electrons. To store a 1 in the memory cell, the buSave Changescket is filled with electrons. To store a 0, it is emptied. The problem with the capacitor's bucket is that it has a leak. In a matter of a few milliseconds a full bucket becomes empty. Therefore, for dynamic memory to work, either the CPU or the memory controller has to come along and recharge all of the capacitors holding a 1 before they discharge. To do this, the memory controller reads the memory and then writes it right back. This refresh operation happens automatically thousands of times per second.
This refresh operation is where dynamic RAM gets its name. Dynamic RAM has to be dynamically refreshed all of the time or it forgets what it is holding. The downside of all of this refreshing is that it takes time and slows down the memory.
Virtual memory is a common part of most operating systems on desktop computers. It has become so common because it provides a big benefit for users at a very low cost.
Most computers today have something like 64 or 128 megabytes of RAM (random-access memory) available for use by the CPU (central processing unit). Often, that amount of RAM is not enough to run all of the programs that most users expect to run at once. For example, if you load the Windows operating system, an e-mail program, a Web browser and word processor into RAM simultaneously, 64 megabytes is not enough to hold it all. If there were no such thing as virtual memory, your computer would have to say, "Sorry, you cannot load any more applications. Please close an application to load a new one." With virtual memory, the computer can look for areas of RAM that have not been used recently and copy them onto the hard disk. This frees up space in RAM to load the new application. Because it does this automatically, you don't even know it is happening, and it makes your computer feel like is has unlimited RAM space even though it has only 32 megabytes installed. Because hard-disk space is so much cheaper than RAM chips, virtual memory also provides a nice economic benefit.
The area of the hard disk that stores the RAM image is called a page file. It holds pages of RAM on the hard disk, and the operating system moves data back and forth between the page file and RAM. (On a Windows machine, page files have a .SWP extension.)
Of course, the read/write speed of a hard drive is much slower than RAM, and the technology of a hard drive is not geared toward accessing small pieces of data at a time. If your system has to rely too heavily on virtual memory, you will notice a significant performance drop. The key is to have enough RAM to handle everything you tend to work on simultaneously. Then, the only time you "feel" the slowness of virtual memory is in the slight pause that occurs when you change tasks. When you have enough RAM for your needs, virtual memory works beautifully. When you don't, the operating system has to constantly swap information back and forth between RAM and the hard disk. This is called thrashing, and it can make your computer feel incredibly slow.
How RAM Works
Random access memory (RAM) is the best known form of computer memory. RAM is considered "random access" because you can access any memory cell directly if you know the row and column that intersect at that cell.
The opposite of RAM is serial access memory (SAM). SAM stores data as a series of memory cells that can only be accessed sequentially (like a cassette tape). If the data is not in the current location, each memory cell is checked until the needed data is found. SAM works very well for memory buffers, where the data is normally stored in the order in which it will be used (a good example is the texture buffer memory on a video card). RAM data, on the other hand, can be accessed in any order.
Similar to a microprocessor, a memory chip is an integrated circuit (IC) made of millions of transistors and capacitors. In the most common form of computer memory, dynamic random access memory (DRAM), a transistor and a capacitor are paired to create a memory cell, which represents a single bit of data. The capacitor holds the bit of information -- a 0 or a 1 (see How Bits and Bytes Work for information on bits). The transistor acts as a switch that lets the control circuitry on the memory chip read the capacitor or change its state.
A capacitor is like a small bucket that is able to store electrons. To store a 1 in the memory cell, the buSave Changescket is filled with electrons. To store a 0, it is emptied. The problem with the capacitor's bucket is that it has a leak. In a matter of a few milliseconds a full bucket becomes empty. Therefore, for dynamic memory to work, either the CPU or the memory controller has to come along and recharge all of the capacitors holding a 1 before they discharge. To do this, the memory controller reads the memory and then writes it right back. This refresh operation happens automatically thousands of times per second.
This refresh operation is where dynamic RAM gets its name. Dynamic RAM has to be dynamically refreshed all of the time or it forgets what it is holding. The downside of all of this refreshing is that it takes time and slows down the memory.
In this article, you'll learn all about what RAM is, what kind you should buy and how to install it. See the next page to learn more about dynamic RAM and memory cells.
Memory Cells and DRAM
Memory cells are etched onto a silicon wafer in an array of columns (bitlines) and rows (wordlines). The intersection of a bitline and wordline constitutes the address of the memory cell.
DRAM works by sending a charge through the appropriate column (CAS) to activate the transistor at each bit in the column. When writing, the row lines contain the state the capacitor should take on. When reading, the sense-amplifier determines the level of charge in the capacitor. If it is more than 50 percent, it reads it as a 1; otherwise it reads it as a 0. The counter tracks the refresh sequence based on which rows have been accessed in what order. The length of time necessary to do all this is so short that it is expressed in nanoseconds (billionths of a second). A memory chip rating of 70ns means that it takes 70 nanoseconds to completely read and recharge each cell.
Memory cells alone would be worthless without some way to get information in and out of them. So the memory cells have a whole support infrastructure of other specialized circuits. These circuits perform functions such as:
* Identifying each row and column (row address select and column address select)
* Keeping track of the refresh sequence (counter)
* Reading and restoring the signal from a cell (sense amplifier)
* Telling a cell whether it should take a charge or not (write enable)
Other functions of the memory controller include a series of tasks that include identifying the type, speed and amount of memory and checking for errors.
Static RAM works differently from DRAM. We'll look at how in the next section.
Static RAM
Static RAM uses a completely different technology. In static RAM, a form of flip-flop holds each bit of memory (see How Boolean Logic Works for details on flip-flops). A flip-flop for a memory cell takes four or six transistors along with some wiring, but never has to be refreshed. This makes static RAM significantly faster than dynamic RAM. However, because it has more parts, a static memory cell takes up a lot more space on a chip than a dynamic memory cell. Therefore, you get less memory per chip, and that makes static RAM a lot more expensive.
Static RAM is fast and expensive, and dynamic RAM is less expensive and slower. So static RAM is used to create the CPU's speed-sensitive cache, while dynamic RAM forms the larger system RAM space.
Memory chips in desktop computers originally used a pin configuration called dual inline package (DIP). This pin configuration could be soldered into holes on the computer's motherboard or plugged into a socket that was soldered on the motherboard. This method worked fine when computers typically operated on a couple of megabytes or less of RAM, but as the need for memory grew, the number of chips needing space on the motherboard increased.
The solution was to place the memory chips, along with all of the support components, on a separate printed circuit board (PCB) that could then be plugged into a special connector (memory bank) on the motherboard. Most of these chips use a small outline J-lead (SOJ) pin configuration, but quite a few manufacturers use the thin small outline package (TSOP) configuration as well. The key difference between these newer pin types and the original DIP configuration is that SOJ and TSOP chips are surface-mounted to the PCB. In other words, the pins are soldered directly to the surface of the board, not inserted in holes or sockets.
Memory chips are normally only available as part of a card called a module. You've probably seen memory listed as 8x32 or 4x16. These numbers represent the number of the chips multiplied by the capacity of each individual chip, which is measured in megabits (Mb), or one million bits. Take the result and divide it by eight to get the number of megabytes on that module. For example, 4x32 means that the module has four 32-megabit chips. Multiply 4 by 32 and you get 128 megabits. Since we know that a byte has 8 bits, we need to divide our result of 128 by 8. Our result is 16 megabytes!
In the next section we'll look at some other common types of RAM.
Types of RAM
The following are some common types of RAM:
* SRAM: Static random access memory uses multiple transistors, typically four to six, for each memory cell but doesn't have a capacitor in each cell. It is used primarily for cache.
* DRAM: Dynamic random access memory has memory cells with a paired transistor and capacitor requiring constant refreshing.
* FPM DRAM: Fast page mode dynamic random access memory was the original form of DRAM. It waits through the entire process of locating a bit of data by column and row and then reading the bit before it starts on the next bit. Maximum transfer rate to L2 cache is approximately 176 MBps.
* EDO DRAM: Extended data-out dynamic random access memory does not wait for all of the processing of the first bit before continuing to the next one. As soon as the address of the first bit is located, EDO DRAM begins looking for the next bit. It is about five percent faster than FPM. Maximum transfer rate to L2 cache is approximately 264 MBps.
* SDRAM: Synchronous dynamic random access memory takes advantage of the burst mode concept to greatly improve performance. It does this by staying on the row containing the requested bit and moving rapidly through the columns, reading each bit as it goes. The idea is that most of the time the data needed by the CPU will be in sequence. SDRAM is about five percent faster than EDO RAM and is the most common form in desktops today. Maximum transfer rate to L2 cache is approximately 528 MBps.
* DDR SDRAM: Double data rate synchronous dynamic RAM is just like SDRAM except that is has higher bandwidth, meaning greater speed. Maximum transfer rate to L2 cache is approximately 1,064 MBps (for DDR SDRAM 133 MHZ).
* RDRAM: Rambus dynamic random access memory is a radical departure from the previous DRAM architecture. Designed by Rambus, RDRAM uses a Rambus in-line memory module (RIMM), which is similar in size and pin configuration to a standard DIMM. What makes RDRAM so different is its use of a special high-speed data bus called the Rambus channel. RDRAM memory chips work in parallel to achieve a data rate of 800 MHz, or 1,600 MBps. Since they operate at such high speeds, they generate much more heat than other types of chips. To help dissipate the excess heat Rambus chips are fitted with a heat spreader, which looks like a long thin wafer. Just like there are smaller versions of DIMMs, there are also SO-RIMMs, designed for notebook computers.
* Credit Card Memory: Credit card memory is a proprietary self-contained DRAM memory module that plugs into a special slot for use in notebook computers.
* PCMCIA Memory Card: Another self-contained DRAM module for notebooks, cards of this type are not proprietary and should work with any notebook computer whose system bus matches the memory card's configuration.
* CMOS RAM: CMOS RAM is a term for the small amount of memory used by your computer and some other devices to remember things like hard disk settings -- see Why does my computer need a battery? for details. This memory uses a small battery to provide it with the power it needs to maintain the memory contents.
* VRAM: VideoRAM, also known as multiport dynamic random access memory (MPDRAM), is a type of RAM used specifically for video adapters or 3-D accelerators. The "multiport" part comes from the fact that VRAM normally has two independent access ports instead of one, allowing the CPU and graphics processor to access the RAM simultaneously. VRAM is located on the graphics card and comes in a variety of formats, many of which are proprietary. The amount of VRAM is a determining factor in the resolution and color depth of the display. VRAM is also used to hold graphics-specific information such as 3-D geometry data and texture maps. True multiport VRAM tends to be expensive, so today, many graphics cards use SGRAM (synchronous graphics RAM) instead. Performance is nearly the same, but SGRAM is cheaper.
You Need To Read This For Your Knowledge..
Computer hacking is the practice of modifying computer hardware and software to accomplish a goal outside of the creator’s original purpose. People who engage in computer hacking activities are often called hackers. Since the word “hack” has long been used to describe someone who is incompetent at his/her profession, some hackers claim this term is offensive and fails to give appropriate recognition to their skills.
Computer hacking is most common among teenagers and young adults, although there are many older hackers as well. Many hackers are true technology buffs who enjoy learning more about how computers work and consider computer hacking an “art” form. They often enjoy programming and have expert-level skills in one particular program. For these individuals, computer hacking is a real life application of their problem-solving skills. It’s a chance to demonstrate their abilities, not an opportunity to harm others.
Since a large number of hackers are self-taught prodigies, some corporations actually employ computer hackers as part of their technical support staff. These individuals use their skills to find flaws in the company’s security system so that they can be repaired quickly. In many cases, this type of computer hacking helps prevent identity theft and other serious computer-related crimes.
Computer hacking can also lead to other constructive technological developments, since many of the skills developed from hacking apply to more mainstream pursuits. For example, former hackers Dennis Ritchie and Ken Thompson went on to create the UNIX operating system in the 1970s. This system had a huge impact on the development of Linux, a free UNIX-like operating system. Shawn Fanning, the creator of Napster, is another hacker well known for his accomplishments outside of computer hacking.
In comparison to those who develop an interest in computer hacking out of simple intellectual curiosity, some hackers have less noble motives. Hackers who are out to steal personal information, change a corporation’s financial data, break security codes to gain unauthorized network access, or conduct other destructive activities are sometimes called “crackers.” This type of computer hacking can earn you a trip to a federal prison for up to 20 years.
If you are interested in protecting your home computer against malicious hackers, investing in a good firewall is highly recommended. It’s also a good idea to check your software programs for updates on a regular basis. For example, Microsoft offers a number of free security patches for its Internet Explorer browser.
Microprocessors are simply a computer processor that has been configured into the design and function of a microchip. Sometimes referred to as a logic chip, this small component functions as the means of executing the command to start booting up a computer. As part of the process, a microprocessor initiates the activation of all the components necessary to allow the computer to be used, such as waking the operating system.
The basic functionality of a microprocessor is all based on the inherent ability to respond to and generate mathematical and logical operations. This function of small computer processors is made possible with the use of registers. Within the registers resides all the data required by the microprocessor to execute such basic functions as addition and subtraction. The configuration of the registers also allow the microprocessor to handle tasks such as comparing two different numbers, and retrieving numbers from various areas and redistributing them.
At the core of the design for the microprocessor is a series of logical instructions that regulate the order that tasks are received and executed. The presence of the instructions assure that tasks are carried out in a sequence that will flow from the completion of one task and into the logical initiation of the next task in the sequence. For example, when an end user boots up a computer, the first instruction that the microprocessor will execute is the activation of the BIOS, or basic input/output system. From that point, the BIOS will load the operating system into the active memory and move on to the next task in the starting process. Each successive task will be achieved once the previous task is complete.
Generally, a microprocessor is a component that remains efficient and productive for the life of the computer. However, it is possible for the functionality of the chip to become damaged in some manner. When this happens, it is usually an easy process for a computer technician to replace the corrupted microprocessor with a fully functioning logic chip.
A network switch is a device that manages the sharing of multiple computers or networks on the same data connection. Another name for a network switch is a network bridge, which is a physical device responsible for routing and processing data within the open systems interconnection model. A network switch does not include hubs or repeaters, as these devices do not include any type of logical processors.
A network switch can support 10/100 Mbit/s (Megabits per second) or 10/100/1000 Mbit/s port transfer rates. It is possible to have multiple network switches operating at different speeds on the same network. However, this type of setup lends itself to bottlenecks and restricts the possible routes available for the flow of data.
A network switch is absolutely critical in the management of a computer network. The network switch functions as the traffic management system within the network, directing data packets to the correct destination. These devices are used to connect peripheral devices to the network and ensure maximum cost effectiveness and the ability to share resources.
A typical setup of a network switch is two computers, one printer, and a wireless router. All the devices are connected to the network switch, and each item must be clearly identified and connection rules created.
Once the setup is done, any computer on the network, can use the same printer. All computers can transfer files to each other and anyone with a wireless card can access the network, print and transfer files. The network switch is designed to allow the resources to be shared without reducing performance.
A simple analogy for a network switch is a policeman at a four-way stop. The cars are the data packets that are sent from each device as it attempts to communicate with the other devices in the network. The policeman, or network switch, directs traffic, sending the data to the right location, without having any collisions.
There are four main types of network switches. The four types are unmanaged switches, managed switches, smart switches, and enterprise managed switches. Each different types has its own strengths and weaknesses that need to be considered.
An unmanaged switch is the cheapest option and is typically used in a small office or business. These network switches perform the basic functions of managing the data flow between a shared printer and multiple computers. They can either be desktop models or rack mounted.
A managed switch has a user interface or software offering that allows users to modify the settings of the switch. There are multiple methods for updating the network switch, ranging from a serial console to an Internet based application. This type of network switch requires a knowledgeable user to adjust the settings as needed.
A smart switch is the middle product offering between a unmanaged and managed switch. The user interface is web-based and set with the most popular default settings. Adjustments to one setting result in an automatic adjustment to the related setting.
An enterprise-managed network switch has a wide range of adjustable settings to allow use within a large company or organization. These types of network switches are usually managed by network specialists and are constantly monitored, due to the size and complexity of the network.
Email forwarding involves passing email along from one address to another. It can also be used to pass groups of messages such as listservs.
Email forwarding services automatically forward all mail received at one of your addresses to another address. This can be handy if you have a web based email alias but would rather not have to surf to the website each day to check your mail. Using a forwarding service, the mail received at the website would automatically be passed to your main email address (or another address of your choice). This allows you the convenience of utilizing multiple email addresses while keeping your main email address private, and still collecting all of your mail in one place.
Mail forwarding services are also handy for people that change their ISP (and therefore main email address) often. With some forwarding services, you are simply give out our one address no matter what ISP you have; the address might look something like: yourname@forwarding-service-provider.com. Friends will always have a current address to send mail, and when your main address changes you only have to notify one party (the forwarding service) rather than dozens.
Many services also offer SMS alerts for mobile email notification and other advanced management features. For example, the email that gets forwarded to you might automatically be distributed into a variety of accounts using filtering technology. Thus, while you can give out a single address to all, the incoming mail would get sorted into categories as it enters your email client. This can be done by setting up several identities in the client. A work identity, a family identity, one for friends, one for listservs or mailing list, for example. With one click you would collect your mail from the forwarding-services's site using their POP3/IMAP server in your configuration. As the mail is retrieved it is automatically sorted into the proper identities for easy management.
In the same way, mail can be sent from your email client using the SMTP server that belongs to the mail forwarding service. This allows you to use an email client rather than the website where the mail forwarding service is located, though you can always use your browser and the website interface instead.
Though using an email forwarding service can be handy, bear in mind that web based email is generally not considered as private or secure as mail kept on an ISP mail server. Web servers are more exposed and the expectation of privacy is usually lower. You may not want to use a service like this for very personal or sensitive information. In any case privacy policies and Terms of Service agreements should be thoroughly read and understood before signing on with any company.
firefox add-ons (sometimes written as addons or add ons) are free software routines or ‘miniature programs’ that work within the Mozilla Firefox browser to customize and personalize it. Firefox is an open-source browser, meaning all of its internal code is freely available to developers, hobbyists, and to the public. This allows a wide range of applications to be written by enthusiasts that bring new, handy features to the browser. The always-growing library of Firefox add-ons are posted at the Firefox website for perusal and download. Firefox installs and updates chosen add-ons automatically with the user’s permission, which makes using Firefox add-ons a snap.
It is nearly impossible to overstate the vast array of optional features available in Firefox through the add-ons library. Some examples include download managers and accelerators, automatic copying of highlight text in a webpage, automatic mapping of a highlighted address, language translators for highlighted text, and dictionary lookup for right-clicked words. There are also many utility add-ons, such as an Internet Protocol (IP) finder that shows the current website’s numerical IP address in the task bar, a cache cleaner button, and a cookie manager add-on that brings up all cookies with the click of a button, allowing deletion or other options. Below are a few more popular Firefox add-ons.
NoScript: This extremely popular add-on places an icon in the system tray and blocks potentially dangerous scripts as a matter of course. To enable scripts on a site-by-site basis, one only has to click the icon and choose to allow scripts for the site either temporarily or permanently. The program generates a “white list” in this way, allowing only those sites you trust to run scripts.
FlashBlock: If you’re tired of annoying flash animations the Flashblock add-on will replace flash scripts with a button. If you want to see the flash display, just click the button. This decreases page-loading time, allowing for faster Web surfing.
ReminderFox: Do you forget things when you’re online because you’re busy cruising your favorite sites? Do you start looking past post-it notes on the refrigerator when they’ve been up a few days? ReminderFox might be just what you need. Add reminders or make a to-do list and let ReminderFox know if you want to be reminded on the day or ahead of time. You can get notices by the minute, hour, day, week, month or even year. Whether you just don’t want to miss your favorite TV program, an eBay auction, a dental appointment, or you need a reminder to pay those bills, ReminderFox can be your personal secretary.
ForecastFox: This add-on brings your local weather forecast to your Firefox task tray. Configure it to show the current temperature and conditions, and the five-day forecast. Highly configurable, view live radar images and much more weather information with the click of the mouse.
SunCult: If you like to keep track of the phases of the moon, sunrise and sunset, SunCult is for you. An icon of the sun and moon sit in the system tray of Firefox, with the moon’s phase reflected by the moon’s icon. A mouseover of the icon brings up the times for sunrise, sunset, moonrise and set, the moon’s phase, and more.
These Firefox add-ons and hundreds more make Firefox the most customizable browser on the Internet. Authors of add-ons provide support in the way of Web forums and often through personal replies if an issue is not covered elsewhere. Firefox themes and plug-ins are also available through the website.
It is important to note that certain add-ons are not compatible with each other. For example, the auto copy and auto-mapping add-ons both rely on highlighting text to perform different functions. As a rule it’s best to load one add-on at a time and make sure Firefox functions correctly before adding another. Firefox add-ons are easily disabled and uninstalled through Firefox.
Network security comprises the measures a company takes to protect its computer system, and it is a prime concern for every company that uses computers. Compromised network security means a hacker or competitor may gain access to critical or sensitive data, possibly resulting in data loss, or even complete destruction of the system.
Appropriate network security is achieved when a user has to go through several layers of security before being able to access the desired network. The more layers the system has, the more secure it is.
The systems administrator is often in charge of network security since he has administrator privileges on the system. In fact, only the systems administrator and his assistants should have administrative access to the mainframe server and related computer terminals. This will help keep unauthorized people in the company from changing any data on the servers.
A systems administrator will also build a secure firewall for the network, which may include an encryption layer and sentinel software that automatically repels an unauthorized program from gaining access. The administrator may also place restrictions on employees' computers to prevent them from accessing websites that may have malicious coding or malware that will install itself on a user's computer. Anti-adware and malware programs are available for individual computers, as well as for networks.
One problem that generally arises when network security is implemented is that of flexibility. Management must balance security issues against employees' ability to access websites for their work. Communication among management, the systems administrator and employees is critical for network security to operate and for the employees to be able to work with it.
As evidenced in dealing with past e-mail and network viruses, security breaches are costly and detrimental to production and efficiency. U.S. companies spend millions of dollars each year in network security measures. A company's best defense against network security breaches is a multi-pronged attack. Firewalls with no single point of access, sharp systems administrators, frequent security updates, and early installation of anti-adware will all help keep a network safe.
Computer hacking is most common among teenagers and young adults, although there are many older hackers as well. Many hackers are true technology buffs who enjoy learning more about how computers work and consider computer hacking an “art” form. They often enjoy programming and have expert-level skills in one particular program. For these individuals, computer hacking is a real life application of their problem-solving skills. It’s a chance to demonstrate their abilities, not an opportunity to harm others.
Since a large number of hackers are self-taught prodigies, some corporations actually employ computer hackers as part of their technical support staff. These individuals use their skills to find flaws in the company’s security system so that they can be repaired quickly. In many cases, this type of computer hacking helps prevent identity theft and other serious computer-related crimes.
Computer hacking can also lead to other constructive technological developments, since many of the skills developed from hacking apply to more mainstream pursuits. For example, former hackers Dennis Ritchie and Ken Thompson went on to create the UNIX operating system in the 1970s. This system had a huge impact on the development of Linux, a free UNIX-like operating system. Shawn Fanning, the creator of Napster, is another hacker well known for his accomplishments outside of computer hacking.
In comparison to those who develop an interest in computer hacking out of simple intellectual curiosity, some hackers have less noble motives. Hackers who are out to steal personal information, change a corporation’s financial data, break security codes to gain unauthorized network access, or conduct other destructive activities are sometimes called “crackers.” This type of computer hacking can earn you a trip to a federal prison for up to 20 years.
If you are interested in protecting your home computer against malicious hackers, investing in a good firewall is highly recommended. It’s also a good idea to check your software programs for updates on a regular basis. For example, Microsoft offers a number of free security patches for its Internet Explorer browser.
Microprocessors are simply a computer processor that has been configured into the design and function of a microchip. Sometimes referred to as a logic chip, this small component functions as the means of executing the command to start booting up a computer. As part of the process, a microprocessor initiates the activation of all the components necessary to allow the computer to be used, such as waking the operating system.
The basic functionality of a microprocessor is all based on the inherent ability to respond to and generate mathematical and logical operations. This function of small computer processors is made possible with the use of registers. Within the registers resides all the data required by the microprocessor to execute such basic functions as addition and subtraction. The configuration of the registers also allow the microprocessor to handle tasks such as comparing two different numbers, and retrieving numbers from various areas and redistributing them.
At the core of the design for the microprocessor is a series of logical instructions that regulate the order that tasks are received and executed. The presence of the instructions assure that tasks are carried out in a sequence that will flow from the completion of one task and into the logical initiation of the next task in the sequence. For example, when an end user boots up a computer, the first instruction that the microprocessor will execute is the activation of the BIOS, or basic input/output system. From that point, the BIOS will load the operating system into the active memory and move on to the next task in the starting process. Each successive task will be achieved once the previous task is complete.
Generally, a microprocessor is a component that remains efficient and productive for the life of the computer. However, it is possible for the functionality of the chip to become damaged in some manner. When this happens, it is usually an easy process for a computer technician to replace the corrupted microprocessor with a fully functioning logic chip.
A network switch is a device that manages the sharing of multiple computers or networks on the same data connection. Another name for a network switch is a network bridge, which is a physical device responsible for routing and processing data within the open systems interconnection model. A network switch does not include hubs or repeaters, as these devices do not include any type of logical processors.
A network switch can support 10/100 Mbit/s (Megabits per second) or 10/100/1000 Mbit/s port transfer rates. It is possible to have multiple network switches operating at different speeds on the same network. However, this type of setup lends itself to bottlenecks and restricts the possible routes available for the flow of data.
A network switch is absolutely critical in the management of a computer network. The network switch functions as the traffic management system within the network, directing data packets to the correct destination. These devices are used to connect peripheral devices to the network and ensure maximum cost effectiveness and the ability to share resources.
A typical setup of a network switch is two computers, one printer, and a wireless router. All the devices are connected to the network switch, and each item must be clearly identified and connection rules created.
Once the setup is done, any computer on the network, can use the same printer. All computers can transfer files to each other and anyone with a wireless card can access the network, print and transfer files. The network switch is designed to allow the resources to be shared without reducing performance.
A simple analogy for a network switch is a policeman at a four-way stop. The cars are the data packets that are sent from each device as it attempts to communicate with the other devices in the network. The policeman, or network switch, directs traffic, sending the data to the right location, without having any collisions.
There are four main types of network switches. The four types are unmanaged switches, managed switches, smart switches, and enterprise managed switches. Each different types has its own strengths and weaknesses that need to be considered.
An unmanaged switch is the cheapest option and is typically used in a small office or business. These network switches perform the basic functions of managing the data flow between a shared printer and multiple computers. They can either be desktop models or rack mounted.
A managed switch has a user interface or software offering that allows users to modify the settings of the switch. There are multiple methods for updating the network switch, ranging from a serial console to an Internet based application. This type of network switch requires a knowledgeable user to adjust the settings as needed.
A smart switch is the middle product offering between a unmanaged and managed switch. The user interface is web-based and set with the most popular default settings. Adjustments to one setting result in an automatic adjustment to the related setting.
An enterprise-managed network switch has a wide range of adjustable settings to allow use within a large company or organization. These types of network switches are usually managed by network specialists and are constantly monitored, due to the size and complexity of the network.
Email forwarding involves passing email along from one address to another. It can also be used to pass groups of messages such as listservs.
Email forwarding services automatically forward all mail received at one of your addresses to another address. This can be handy if you have a web based email alias but would rather not have to surf to the website each day to check your mail. Using a forwarding service, the mail received at the website would automatically be passed to your main email address (or another address of your choice). This allows you the convenience of utilizing multiple email addresses while keeping your main email address private, and still collecting all of your mail in one place.
Mail forwarding services are also handy for people that change their ISP (and therefore main email address) often. With some forwarding services, you are simply give out our one address no matter what ISP you have; the address might look something like: yourname@forwarding-service-provider.com. Friends will always have a current address to send mail, and when your main address changes you only have to notify one party (the forwarding service) rather than dozens.
Many services also offer SMS alerts for mobile email notification and other advanced management features. For example, the email that gets forwarded to you might automatically be distributed into a variety of accounts using filtering technology. Thus, while you can give out a single address to all, the incoming mail would get sorted into categories as it enters your email client. This can be done by setting up several identities in the client. A work identity, a family identity, one for friends, one for listservs or mailing list, for example. With one click you would collect your mail from the forwarding-services's site using their POP3/IMAP server in your configuration. As the mail is retrieved it is automatically sorted into the proper identities for easy management.
In the same way, mail can be sent from your email client using the SMTP server that belongs to the mail forwarding service. This allows you to use an email client rather than the website where the mail forwarding service is located, though you can always use your browser and the website interface instead.
Though using an email forwarding service can be handy, bear in mind that web based email is generally not considered as private or secure as mail kept on an ISP mail server. Web servers are more exposed and the expectation of privacy is usually lower. You may not want to use a service like this for very personal or sensitive information. In any case privacy policies and Terms of Service agreements should be thoroughly read and understood before signing on with any company.
firefox add-ons (sometimes written as addons or add ons) are free software routines or ‘miniature programs’ that work within the Mozilla Firefox browser to customize and personalize it. Firefox is an open-source browser, meaning all of its internal code is freely available to developers, hobbyists, and to the public. This allows a wide range of applications to be written by enthusiasts that bring new, handy features to the browser. The always-growing library of Firefox add-ons are posted at the Firefox website for perusal and download. Firefox installs and updates chosen add-ons automatically with the user’s permission, which makes using Firefox add-ons a snap.
It is nearly impossible to overstate the vast array of optional features available in Firefox through the add-ons library. Some examples include download managers and accelerators, automatic copying of highlight text in a webpage, automatic mapping of a highlighted address, language translators for highlighted text, and dictionary lookup for right-clicked words. There are also many utility add-ons, such as an Internet Protocol (IP) finder that shows the current website’s numerical IP address in the task bar, a cache cleaner button, and a cookie manager add-on that brings up all cookies with the click of a button, allowing deletion or other options. Below are a few more popular Firefox add-ons.
NoScript: This extremely popular add-on places an icon in the system tray and blocks potentially dangerous scripts as a matter of course. To enable scripts on a site-by-site basis, one only has to click the icon and choose to allow scripts for the site either temporarily or permanently. The program generates a “white list” in this way, allowing only those sites you trust to run scripts.
FlashBlock: If you’re tired of annoying flash animations the Flashblock add-on will replace flash scripts with a button. If you want to see the flash display, just click the button. This decreases page-loading time, allowing for faster Web surfing.
ReminderFox: Do you forget things when you’re online because you’re busy cruising your favorite sites? Do you start looking past post-it notes on the refrigerator when they’ve been up a few days? ReminderFox might be just what you need. Add reminders or make a to-do list and let ReminderFox know if you want to be reminded on the day or ahead of time. You can get notices by the minute, hour, day, week, month or even year. Whether you just don’t want to miss your favorite TV program, an eBay auction, a dental appointment, or you need a reminder to pay those bills, ReminderFox can be your personal secretary.
ForecastFox: This add-on brings your local weather forecast to your Firefox task tray. Configure it to show the current temperature and conditions, and the five-day forecast. Highly configurable, view live radar images and much more weather information with the click of the mouse.
SunCult: If you like to keep track of the phases of the moon, sunrise and sunset, SunCult is for you. An icon of the sun and moon sit in the system tray of Firefox, with the moon’s phase reflected by the moon’s icon. A mouseover of the icon brings up the times for sunrise, sunset, moonrise and set, the moon’s phase, and more.
These Firefox add-ons and hundreds more make Firefox the most customizable browser on the Internet. Authors of add-ons provide support in the way of Web forums and often through personal replies if an issue is not covered elsewhere. Firefox themes and plug-ins are also available through the website.
It is important to note that certain add-ons are not compatible with each other. For example, the auto copy and auto-mapping add-ons both rely on highlighting text to perform different functions. As a rule it’s best to load one add-on at a time and make sure Firefox functions correctly before adding another. Firefox add-ons are easily disabled and uninstalled through Firefox.
Network security comprises the measures a company takes to protect its computer system, and it is a prime concern for every company that uses computers. Compromised network security means a hacker or competitor may gain access to critical or sensitive data, possibly resulting in data loss, or even complete destruction of the system.
Appropriate network security is achieved when a user has to go through several layers of security before being able to access the desired network. The more layers the system has, the more secure it is.
The systems administrator is often in charge of network security since he has administrator privileges on the system. In fact, only the systems administrator and his assistants should have administrative access to the mainframe server and related computer terminals. This will help keep unauthorized people in the company from changing any data on the servers.
A systems administrator will also build a secure firewall for the network, which may include an encryption layer and sentinel software that automatically repels an unauthorized program from gaining access. The administrator may also place restrictions on employees' computers to prevent them from accessing websites that may have malicious coding or malware that will install itself on a user's computer. Anti-adware and malware programs are available for individual computers, as well as for networks.
One problem that generally arises when network security is implemented is that of flexibility. Management must balance security issues against employees' ability to access websites for their work. Communication among management, the systems administrator and employees is critical for network security to operate and for the employees to be able to work with it.
As evidenced in dealing with past e-mail and network viruses, security breaches are costly and detrimental to production and efficiency. U.S. companies spend millions of dollars each year in network security measures. A company's best defense against network security breaches is a multi-pronged attack. Firewalls with no single point of access, sharp systems administrators, frequent security updates, and early installation of anti-adware will all help keep a network safe.
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