On the Net

with Alex Clarke

Understanding Computers part 4

This week I will cover a few miscellaneous topics, in no particular order. If there are any specific terms you would like to see defined in this column, please emai me at aclarke@nrg.com.au.

Bandwidth

All information in a computer takes up some space in memory, as explained in a previous column. The amount of memory used depends upon the type of information. Text uses the least amount, followed by images, audio and finally video.

In order to transmit information between two computers, there needs to be some sort of channel or connection between them. Usually this is some form of wired connection, like a network cable or a telephone wire. (See also WiFi below).

Bandwidth is the measure of how much information can be physically transfered in a given amount of time. Some connections allow more information to be transmitted - they have higher bandwidth. Bandwidth is measured in bits per second (b/s).

A telephone line can be used with a regular analog modem to provide a dial-up connection, which has very low bandwidth: less than 56,000 bits per second (56Kb/s). At this rate an image file may take a few seconds to download, but a movie file may take many hours.

Alternatively, a telephone line with a special digital modem can be used as an ADSL connection, which has relatively high bandwidth (broadband), up to 1,500,000 bits per second (1500Kb/s). That movie file would arrive up to 25 times faster on this broadband connection than over a 56K dial-up connection.

Downloads

An Internet Service Provider is a business that provides a connection between your computer and the internet. As such, they are selling bandwidth - so they measure exactly how much data passes across that connection into your computer each month. The total amount of data is known as your Downloads.

Every image you view in a web browser, every piece of text and every movie file you view is counted toward your downloads - along with any programs or files you may actually download onto your hard disk.

Most ISPs provide both Limited and Unlimited plans. The Limited plans are typically cheaper, but once you have passed a certain amount of data, the ISP starts charging you an excess per MB extra that you download. Usually this limit is set at 200MB per month, which is what a light internet user might use.

Unlimited plans on the other hand are more expensive but, if you are an intensive internet user, they will actually save you money each month. A better option if you want to listen to music, internet radio, download video or view many image files.

Local Area Network (LAN)

Modern offices often have a small network connecting their computers together, known as a LAN. LANs are also becoming increasingly popular at home, as they allow computers to share a single internet connection, play networked games, share music and files, and more. The common standard for LANs is known as Ethernet, which utilises enhanced telephone-like cables and connectors. If more than two computers are to be connected, a LAN requires a special piece of equipment known as a Hub to manage the data traffic.

WiFi or Wireless Networking

In the last year there has been a large increase in the popularity of wireless networking. PCs call this WiFi, Apple calls it Airport, but it is the same thing - IEEE 802.11b/g. Essentially this is a standard for Ethernet without cables, instead using low powered microwave transceivers to communicate within a radius of about 30 metres. WiFi hardware is more expensive than cabling, but may be more convenient - especially for laptop computers which can roam around within the range of a WiFi network and maintain their network connection.

The bandwidth of 802.11b is 11Mb/s, and 802.11g supports 54Mb/s, both of which are way faster than ADSL, but slower than wired Ethernet.

A WiFi setup consists of a Base Station, which is a wireless hub, and a WiFi card for each networked computer.

With appropriate aerials, WiFi can actually be used over quite a distance - up to 15km with line-of-sight - and so offers hope for broadband connections in remote areas outside of ADSL range.

HotNews

Oops, the big cat is out of the bag... Apple has remained coy about the exact release date of its next OS, 10.4 Tiger.

Up 'til now they have said only that it will be available "in the first half of 2005". But last week Amazon.com, one of Apple's major resellers in the US, inadvertently revealed a ship date of March 31, 2005. While software ship dates are notoriously prone to slippage, at least Mac fans now know they won't see Tiger before this date.

HotSites

www.apple.com/macosx/tiger/

But what's the fuss all about? Check out Apple's official sneak preview of some of the main features of the next major update to OS X. Apple's industry leading technologies just keep moving further and further ahead. And as usual, the features available in Mac OS in 2005 will show up in Windows sometime around 2007. Anyone with a FireWire Mac will be able to update to 10.4 Tiger for $229.

• Alex Clarke can be contacted at PowerMax Computers on 6622 4996, or aclarke@nrg.com.au.

• Chris Goh is taking a holiday and Alex will be writing on the internet and computers over the coming weeks.