Buying a Refurbished Laptops

Refurbished LaptopsComputing freedom, independence, and mobility don’t have to come with a hefty price tag. Manufacturers refurbish laptop is the laptop computers that have been returned. The laptop might have a scratched screen or other minor blemish.

In some cases, the laptop was an unwanted gift or its packaging was dented. The laptop is inspected by the manufacturer, tested for quality, and repackaged for sale at a much lower price.

While many new laptops can cost thousands of dollars, most refurbished laptop computers usually cost less than a couple of grand, and often less than $500. In most cases, they are as good as new and have a very low return rate. They even come with guarantees and warranties, just as you would expect with a new model.

A refurbished laptop can satisfy most people’s basic computing needs, such as word processing, running software, reading e-mail, creating spreadsheets, playing CDs, surfing the Internet, and more. Laptops allow access to all these features from anywhere.

All laptop manufacturers offer refurbished laptops, including such popular brands as Dell, IBM, Toshiba, and HP.

Laptop prices are affected by type of processor, operating system, modem, and network card; size of the hard drive and RAM (Random Access Memory); and whether there is a CD/DVD-ROM/RW, a video card, a sound card, and zip drive. Prices are also affected by screen size and type of chassis.

The price will be affected by all these specifications, along with how well preserved the chassis is, the name of the manufacturer, and whether you acquire the laptop form the factory or through a private dealer. Private dealers charge less, but beware: not all dealers are up to par with their refurbishing skills. Be sure to go to one that is reputable and experienced.

How Computers Count

How Computers CountThe world around us has many aspects which work in the same way as a computer. There are many examples of opposites, for instance Up and Down, Left and Right, Forwards and Backwards. A light may be On or Off, maybe it’s Night or Day. Yes or No? You can think of many others.

This system of two possible states is called a Binary System. If it’s not one, it must be the other.

A computer uses the Binary System to perform all its functions. The basic unit, originally made from a vacuum tube, then a transistor, then a chip, is used thousands of times over to make the total unit. The light being On or Off which we mentioned above is controlled by a switch. In the computer this switch is a transistor, which is either On or Off.

The Binary system is a Number System. You are familiar with the Decimal system which has 10 numerals 0 to 9 (think like a computer 0 comes first). You can make up all sorts of number systems for whatever purpose you want. You probably know about a dozen (12) and have also heard of a half dozen.

If you’ve used your computer much you may have come across the Hexadecimal system. This one has 16 ‘numerals’ 0-9and A-F. Another number system used by computer people is the Octal system which has 8 numerals, 0-7.

So, how do we count with only 0 and 1. Simple, in exactly the same way you count in decimal. The first ten numbers are OK, 0-9, but what next? We start again but add in a 1 making 10 or “one, zero”. This gets us to “one, nine” and we go to “two, zero”, and so on up to “nine, nine” then we again add a 1 to make 100 – “one, zero, zero.”

DECIMAL 0-9, 10-19, 20-…..-99, 100.

In the Binary sequence, it’s much simpler. Starting off at zero we have 0,1 – and that’s it. We follow the same rule and add in a 1, making “one,zero”. Next come “one, one”; then “one, zero, zero”; -“one, zero, one”; etc. These are equivalent to Decimal 0,1,2,3,4,5. How does this relate to computers? That’s next.

BINARY – 0 1 10 11 100 101

DECIMAL- 0, 1, 2, 3, 4, 5

In our computer we have transistor switches, as described above. For the math example we just looked at, we need 3 switches. These each represent a Binary Digit, or Bit. To represent a Decimal 1, these switches would be OFF,OFF,ON or 001. For a Decimal 5 we would have ON,OFF,ON, or 101. By extension you can see that with 4 switches we could go to 1111 or 15 Decimal.

TRANSISTORS [OFF OFF ON] [ON OFF ON] [ON ON ON ON]

BINARY…… 001 101 1111

DECIMAL….. 1, 5, 15

Another point to note is that each binary digit, or bit, has a value. Just as in Decimal we have units, tens, hundreds, etc. in Binary the values are 1,2,4,8,16,32,64,128 etc. etc. The binary code 1111 mentioned above is thus 1+2+4+8=15. what would BINARY 1010 be in decimal?

BIT VALUE 8 4 2 1

BINARY…. 1 0 1 0

DECIMAL… 8+2=10

If you wanted to work out what binary 100101100 was in decimal, you could add up the individual values. In fact people who work on the basic machines need to know “machine code”! To them 1010 would be A in Hexadecimal or 12 in octal.

One of the reasons for using the octal or hexadecimal code is to enable humans to interpret machine codes. Some mainframe computers use ‘words’ composed of 24, 32, 36 or 72 bits. These are displayed or printed in groups of three for octal, or four for hexadecimal. For example the 24 bit binary word in a computer may be interpreted as shown here.

BINARY 100 111 000 011 010 000 011 100

OCTAL.. 4 7 0 3 2 0 3 4

BINARY 1001 1100 0011 0100 0001 1100

HEX…. 9 D 3 4 1 D

This probably seems a very long-winded way to work out numbers, until you remember that these ‘switches’ can operate at nanosecond speed, in the order of 1,000,000,000 times per second, large calculations become possible.

Cleaning the Clogged Printhead

Cleaning the Clogged PrintheadIf your inkjet or bubblejet printer has clogged printheads there are 2 possible reasons:

Ink has dried in the nozzles

It is important to note that although genuine inks have anti-clogging agents in their formulation, if you have not used your printer in a long time the ink will dry up in the printhead. With genuine inks a couple of head cleans will usually get the ink flowing again.

If you are using refill or compatible cartridges more aggressive head cleans may be necessary. You may need printhead cleaning solution. The best way to stop ink drying in the printhead is to use your printer every week. Just print out a test page which will use black and colour.

Foreign matter has blocked the holes in the nozzles.

This is caused by foreign matter in the ink – always from small unfiltered particles from refill ink or lower quality compatible cartridges manufactured in a dusty environment – or the printhead collecting paper dust from poor quality paper, or the printhead picking up muck in an overfull parking station.

What is a parking station? This is where the printhead sits when the printer is not printing, usually on the right hand side inside the printer. There is a small rubber cap here which sits under the printhead to protect and prevent it drying out. On most printers it also provides a cleaning function and there is a lot of waste ink in this area- so it is the perfect place to collect dust and muck.

You can get a cotton bud in there and clean it by switching the printer off then on, and then when the printhead moves away from the parking station switch the printer off at the wall. You will then be able to access this area for cleaning.

If foreign matter in the ink has blocked the printheads and your printhead is fixed into the machine, put new original cartridges in your machine as this will usually dissolve any particles in the printhead. If your printhead is removable, take it out of the machine and sit it in about 5ml of very hot (not boiling!) water for a few minutes.

Dry thoroughly and re-insert into the machine and do a couple of printer head cleans. Repeat until the nozzles are unblocked. Always use good quality inks or compatibles in your printer – original inks are always best.

If you open your printer and you can see a fine white powder inside the machine, this is paper dust. This is getting into the print nozzles!

Always use good quality paper and once in a while use compressed air to clean out the inside of your printer (use a can of compressed air, not compressed air from a compressor – or you’ll blow away the electronics in your printer!).

Basic Equipment for Computer Network

Computer NetworkA computer network is a connection between two or more computers that is connected with cable or wireless device. Other peripheral devices that can be connected with computer can also be included in this network such as wireless receivers, printers, scanner, camera, etc.

This connection will make the information or data sharing between each computer and terminal become easier and less time consuming. Every computer and other devices inside a network are called a node.

There are no limits how much nodes that can be connected to a single network. Many big organizations could have millions of nodes in their network.

To make a network connection between nodes, it will require several tools or equipment. Here are some of the most important tools to make a network.

Network cabling

Cabling is use to connect a node to the central hub. These days many organizations are using fiber optic cable that have better ability in sending the data for their network cabling.

Network Adapter

This interface device can be found inside the computer and wireless receiver or router. This device will transfer and receive the data or information to and from the central or hubs. The adapter will influence the speed of data transfer in the network.

Hubs

This is the main device that gathers and connects all the nodes to become a network. The size of hubs depends on how many nodes that is in the network. For large network, it will require many hubs to be able to support many nodes.

Switches

Switches act as a terminal to control the data traffic between nodes and also hubs. It will connect a data from a node to its destination node correctly, more effectively and efficient. Therefore the data transfer will not crash to other data from different nodes that will make the connection halted or crash. A switch is also use to connect nodes that has different speeds to other nodes, so the connection speed will improve.