Category: Computers & Technology

What Makes a Concurrent Algorithm Correct?


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First of all one must ask themselves what makes any algorithm correct? The answer is the algorithm does as it is required by a specification or set of interested properties. For example a specification which states the algorithm will sort as list of unsorted numbers in ascending order, is correct if it does just that.

This brings us onto defining what makes a correct concurrent algorithm. As with any algorithm or computer program, we require that it produces the expected output from the data that is input into the system. Additionally when concurrency is brought into the mix there are two more properties we are concerned with. The first is mutual exclusion of shared resources, in order to prevent the problematic results race conditions can produce. Secondly we want to be sure the algorithm doesn’t result in deadlock or livelock.

To conclude we can say that a concurrent algorithm is correct if it meets the following requirements:

  • It is safe – shared resources are suitably protected
  • The required result eventually happens – free from deadlock and livelock

Video Explanation

The Malware Paradox

VirusWhat is Malware?

Malware is short for “malicious software”. It is any type of software with a malicious intent. This includes computer viruses, spyware/trojan horses, worms, some online scripts and some tracking cookies. We tend to use the term “computer virus” to mean all of these things, but technically this is incorrect.


Image courtesy of Salvatore Vuono /

Those Involved

There are two parties who have an interest in the development of malware, both of which would lose their jobs if it was to go away. They are the malware developers and the security package developers; they are both, in most cases, after your cash. I shall point out here, there will always be those out there to cause damage, meaning we need some “good guys and girls” to help prevent and repair that damage.

The Anti Malware Problem

The problem occurs when there is so much money to be made in security products and too many people using insecure computers. This makes it easier for programmers to write more malware with increased scales of damage. These “bigger” and “worse” malware programs then reach the media, where they are hyped up out of proportion, in many cases. The “experts” then recommend everyone updates their anti virus software and make sure it is from a “decent” provider.

Image courtesy of Stuart Miles /

Image courtesy of Stuart Miles /

Securing Your Computer

The fact is there is so much more to securing a computer than just installing anti virus software and a firewall; they are simply the easiest things to do. Additionally the internet is a constant threat and there is no time to be spent with your feet up. Whether it is topical in the news or not, you should have good computer practices, which ensure that your computer is in the best possible state to fend off malicious software and attackers.

Some good practices are:

  • Keeping all your software and drivers up-to-date
  • Running up-to-date quality anti virus / malware software, free or paid – good free ones for include Avast and AVG – good paid ones include Bit Defender and my personal favourite ESET NOD32
  • Running a well configured firewall on your computer and network
  • Turning off unnecessary features
  • Using strong passwords
  • Being careful when opening email attachments – how to spot a phishing email
  • Don’t click on anything that looks suspicious – check with someone else if you’re not sure
  • Keep regular backups

Remember if you are running Windows, Mac OS or Linux/Unix, any computer to be precise, it can get malware/viruses.  The chances are if you aren’t running Windows you won’t get any, yet it is important to remember they are out there and it is wise to take steps to prevent them. For those not running Windows you probably don’t need anti virus, but a firewall is very much advised as well as adhering to good practices will probably keep you safe.

What if You Get Malware?

If you suspect you have malware/viruses on your computer, I advise you get it checked out ASAP and don’t use the computer until you’re sure it’s safe. A really good free program for finding a removing malware is Malware Bytes. It has a good track record dealing with most occurrences of malware and it is easy-to-use.


All in all I’d consider malware to be the fourth biggest threat to IT. It’s important to take steps to prevent it, but more fuss is made about it than there needs to be. So keep calm, take steps to prevent malware and carry on!

Creating and Remembering Strong Passwords

Password CrackerWith crackers becoming more and more cunning in their methods and attempts to steal your data, it is more important than ever to use “secure passwords” that make it difficult for crackers to break. Not only that, it is imperative that you use a range of different secure passwords for different sites. This is because in the event of one of your passwords being compromised, the others will remain safe.

What makes a password “secure”?

Secure Password LockThere a variety of things that make a password secure, these are some of them:

  • 8 or more characters long
  • Use of both upper and lower cases
  • Use of letters, numbers and symbols
  • Passwords not made of dictionary words, names and dates, etc.

How can I make a secure password that is also easy to remember?

This video from Sophos explains a very good way of creating secure passwords that you’ll remember and briefly covers a solution to managing lots of different passwords.

Sophos is UK computer security company who have been making security software for industry for decades. Find out more about Sophos here.

How can I test my password?

KeysThere are now a variety of tools available which try and guess how long it might take to crack your password. Why not test it and see how your new “secure” password compares to your old one.

How to Keep Using Windows After April the 8th 2014

For many people upgrading from Windows XP is just not an option for a variety of reasons, others may just choose to keep it. Microsoft will end support on April the 8th 2014 which means there will be no more security patches available. If your staying loyal to Windows XP and intend to keep using it after April the 8th 2014, these YouTube videos will help to improve your security after that time:

Securing Windows XP Part 1

Securing Windows XP Part 2

Securing Windows XP Part 3

Securing Windows XP Part 4

Farewell Windows XP

RIP Windows XPWindows XP is probably Microsoft’s biggest success story for Windows. It has been around for about thirteen years, been the number one operating system for much of that time, now it is number two. It is still more popular than Windows Vista, Windows 8.x, Mac and Linux in the Desktop arena. Now Microsoft says it’s time to say good bye to Windows XP.

It first became available to purchase in 2001. Unlike its predecessors it was much more visually attractive, with its brightly coloured windows and task bar and pleasant photo (Bliss) for a default background, rather than a plain colour. Apart from that it was much like Windows 2000 with a couple of extra features such as Windows Movie Maker, which first appeared in Windows ME.

Windows XP Desktop

Windows XP Advert

Initial Drawbacks to Windows XP

Like many fledgling operating systems, Windows XP had a number of issues. Firstly like most of Microsoft’s new software, it was heavier than all the others that had come before it, however it did claim to boot faster than some of the other ones, which I think it did, if you compared it to Windows 2000. Secondly it was incredibly buggy and unstable, this meant many organisations backed off it for a while until it had matured.

Internet Explorer 6 also was a bit of a drawback to Windows XP, it did things differently to other browsers, therefore web developers had to adapt to support it. Additionally IE6 never passed the Acid 3 security test. Ironically IE6 became one the longest living and popular browsers the world has ever seen, it is still used today by some organisations. Later Microsoft created Internet Explorers 7 and 8 for XP which helped a lot, but they are still no match for other competitive browsers such as Mozilla Firefox, which also supports XP.

Windows XP Activation

This is a drawback that never ever went away from Windows XP and has been in every version of Windows and Office since. Windows activation was installed to try and prevent software piracy, instead it has appeared to have caused more problems than it has solved. It has not stopped people using unlicensed copies of Windows. Instead it makes setting up a genuine versions of XP a pain because the system sometimes thinks it is not genuine. You then have to waste time ringing up Microsoft up to resolve the issue.

A Bit Later

Once some of the major bugs had been addressed for Windows XP and hardware had moved on to have better native support, XP became one of the most popular operating systems in the world. Even when Windows Vista came along, it was no match for XP with its new reliability making it very popular in organisations and in homes. This was something Vista never really achieved. It appeared that nothing could get in its way of XPs success, until the arrival of Windows 7 in 2009. Windows 7 did everything XP did and a bit more.

Windows XP Today

Today Windows XP is the worlds second most favourite operating system, with Windows 7 at number one. It massively out performs Microsoft’s new Windows 8, in terms of popularity, which is proving a bit of a “flop” for Microsoft. Next month after about thirteen years of support, Microsoft will lay Windows XP to rest.

What does this mean to me?

After April the 8th 2014 Microsoft will stop providing security updates for XP. Therefore you have a potential security risk if your computer is still running XP.

What should I do?

If you don’t use your XP computer for anything sensitive then you might be okay for a while using your machine, otherwise your most likely going to need to upgrade. Most likely if your running Windows XP your computer will run sluggishly on Windows 7 and 8 so you have two options:

  1. Buy a new computer
  2. Upgrade to Linux

Microsoft has their own update guide here, but it does not factor in the free Linux option or if you have more brass than sense the Mac option.

Windows 7 or Windows 8

Users used to Windows XP will probably find it easier to adapt to Windows 7 rather than Windows 8 which adopts a completely different interface. To get a computer with Windows 7 you’ll probably need to visit a specialist computer store or buy second hand. Buying second hand is a cost effective way of getting a new computer that does everything you need it to do, with minimal hassle, making it a great choice for many users coming off Windows XP.

Choosing Linux … it’s Free!

To find out why Linux Mint is a good choice of operating system, take a look at this.

Linux Mint can be acquired from here.

Linux Mint Cinnamon

Linux Mint 16 Cinnamon

If you have a particularly old or slower computer you may find Lubuntu to be a fast and functional system that will do pretty much everything any other modern computer system will. The only drawback is it does not look as pretty, but is still easy to use. You can find out more about Lubuntu here.

Lubuntu 13.10

Lubuntu 13.10

Good Bye Old Friend

Windows XP Shutting Down

Top Free Software

Linux Mint

Official Website >

Libre Office

Official Website >


Official Website >


Official Website >


Official Website >


Official Website >


Official Website >

CD Burner XP

Official Website >

Computer and Technology Glossary

Malware is an abbreviation for “malicious software”, that is software with malicious intent.
LiFi is short for Light Fidelity, a wireless high speed networking technology using visible light. Read more about LiFi
WiFi is short for Wireless Fidelity, a networking technology using microwaves instead of wires.

LiFi Wireless

The Sun

Importance of Light

Since the beginning there has been light. We’ve used it for many applications over the years, the most basic being to allow for sight. Light has also been used as way of communicating for centuries. In more recent decades light has become an essential part of high speed digital communication, in the form of fibre optics. Fibre optics allows for lots of data to be sent, very quickly, all over the world, using very long glass cables. However fibre optics can be expensive and still requires cables, which sometimes can be useful for security, but not always practical.

What is LiFi?

Recently researchers have discovered a way of using light for wireless communications as well. They have dubbed it LiFi or Light Fidelity. It works using LED bulbs, similar to ones emerging for use in homes. You will be able to use the same, specially configured, light bulb to light your room and act as a LiFi Access Point.

Click on the diagram to find out more about how LiFi could work.

LiFi Access Point Diagram

How a LiFi Wireless Access Point System Could Work Using Room Lighting

LiFi works by turning LEDs on an off again, at a speed that is subtle enough to not be detectable by the human eye, but still slow enough for the receiver. Due to the vast amount of colours or wavelengths there are in the visible light spectrum, many numbers of LiFi channels are available. This means that plenty of data can be transferred simultaneously using multiple channels.

What if I Want to Turn the Light Out?

Turning a LiFi lamp offThankfully the boffins are already onto this problem. They are currently working on a way of dimming the LEDs to the point that you cannot see the light coming from them, but the computer LiFi receiver can. Clever stuff!

Advantages of LiFi over WiFi

Significantly Lower Power Consumption

LiFi has a very low power consumptionRadio masts are very inefficient and require vast sums of power in order to broadcast and in some cases keep them cool enough to operate. LEDs on the other hand use very little power (much less than a fluorescent bulb), meaning LiFi also uses very little power. At the same time LiFi can also light a room, meaning it can do two jobs for the price of one.

LiFi Has More Channels

PrismThe radio frequency is running out of “free” channels that we can use. The visible light spectrum, which LiFi uses, has vastly more potential channels and therefore would help solve this problem.

LiFi is Safer to Use

SaferWiFi and other radio waves can be dangerous to use in some places, such as areas with flammable gas in the air. Light on the other-hand is used in these areas and is known to be safe, therefore LiFi is a viable technology that could be used.

Microwave wireless devices, such as mobile phones and WiFi routers, have much evidence to suggest they have negative health effects. Natural light is essential to life on earth and known to be safe. LEDs were invented by Oleg Losev in 1927 and so far appear to be safe also, therefore LiFi should be much safer than WiFi.

LiFi is More Secure

More SecureOne of WiFi’s biggest pit falls is it will travel through walls and out of a buildings, therefore leting anyone to try and connect to it. LiFi will not travel through walls, it can only go where light can travel. Therefore if you close your blackout curtains, not even someone stood directly outside your window will be able to try and connect to your LiFi network.

Harald Haas’s LiFi TED Talk

LiFi Sources and Further Information

Error 404!


Error 404 Page Not Found

Error 404, that very annoying page that you hit when a web page cannot be found. Mostly very boring and irritating, but is it always going to be that way? This short video from TED suggests that maybe the Error 404 page is turning into something less boring and more sympathetic. Traditionally the Error 404 page had only one purpose, to deliver the sad news, that the page you really wanted could not be found, however as Renny Gleeson illustrates, for some websites, Error 404 pages are becoming a little more interesting.