Thursday, 28 May 2009
ALPHA
Wednesday, 27 May 2009
CRIT
Thursday, 14 May 2009
ASCII
Computers don't speak English or any other human language. Deep down in the operating system heart, they speak a language comprised of 0s and 1s, or bits. While the first computer programmers wrote their programs in bits, someone determined that it would be easier to have the computer convert human language into bits rather than do the conversion manually. To allow humans to type, a code was developed to convert human letters into 0s and 1s that the computer could understand.
ASCII is a 7-bit character set where each character is defined by 0s and 1s. Every letter in English, and most Romance language (like French or Italian) characters are represented by an ASCII code. For example, the letter A is ASCII code 65. When you write in a text editor, the letters you type are converted to ASCII before they are sent to the computer processor.
Wednesday, 13 May 2009
Death of morse code
Bruce Morris, from Tywyn, Gwynedd, has special dispensation to contact Portishead Radio by morse code.
The station has been the seaman's worldwide link with the mainland for decades.
But Maritime Morse Code will be scrapped on Sunday, bringing to an end a 100-year association between the maritime industry and the earliest form of wireless communication.
Mr Morris has turned his study at home into a living museum dedicated to morse code, reconstructing a merchant navy wireless telegraph station.
Items in his study include a polished brass, morse key, transmitters, receivers, gleaming dials and even a porthole.
Distress calls
The former merchant sailor will dress up for the event in a radio operator's uniform, adding an authentic touch to proceedings.
The morse code system in the UK has been phased out in preference to a satellite safety system.
Stations that used to pick up ships' distress calls have been replaced by satellite receivers.
Morse was invented in the United States and the first message was sent to Washington in 1844.
By the beginning of this century, dots and dashes were being tapped out by ships and remote settlements across the world.
It can be communicated using a torch, tapped by prisoners on pipes or even spoken.
At the beginning of this century, Britain set up listening posts around the coasts to safeguard shipping, the first and most famous SOS being broadcast by the Titanic on her doomed maiden voyage.
Since last year, all ships have been obliged to carry automatic distress beacons which can tell the nearest coastguard where they are, what the problem is and what the ship's name is.
QUOTE
Code "efficient and effective"
Round-the-world yachtsman Sir Robin Knox-Johnston said: "I think it's sad. It's efficient, it's effective, it's very positive. It's not difficult to learn, and at the end of the day when all the fuses blow, when all the electrics break down, provided you have got a few batteries left, you can still send an SOS."
MODERN USAGE OF MORSE CODE
Torch used in Morse code rescue | ||
Coastguards in Hampshire have rescued a sailor who used his torch to flash an SOS message in Morse code. The man, who was taking his 28ft (8.5m) boat from Emsworth to Thorneham Marina when it began to take on water, had no safety equipment onboard. His SOS was picked up by Steve Mann at Hayling Island Sailing Club on Thursday evening, who responded by switching the control tower lights on and off. Mr Mann said: "I was absolutely amazed to see the flashed SOS message." 'Extremely dangerous' The man had recently acquired a new boat and had transferred all his safety equipment onto it. Mr Mann, of Hayling Island Coastguard, said: "This man was caught out on the one occasion he went to sea with absolutely no safety equipment. "Even without radio communication going to sea without even a portable flare is extremely dangerous and could cost you your life." Coastguards and the RNLI lifeboat brought the man and his boat back to shore, where he was checked over by paramedics. |
MORSE OPERATOR
I volunteered my services in 1942. I was sent to Wrexham for one month, this was for induction training. Upon completion of this training I was sent to the Isle of Man for Morse Code training. I was selected for Morse Code training because I had learnt German at school. The training was very intense, during the training we were taught how to use four different wireless receivers. The Morse Code itself was taught in blocks six, letters or numbers. [This story was submitted to the People's War site by Wolverhampton Libraries on behalf of Susan Hannaway and has been added to the site with her permission. The author fully understands the site's terms and conditions]
After completing my training I was posted to Harrogate, Yorkshire. Along with the other trainees I lived in Nissen huts in the grounds of a girls school. We had bunk beds to sleep in and stone hot water bottles to keep us warm.
We were transported to work at the radio station in trucks, still to this day I do not know where I worked as we were transported in secret. We would work in rolling shifts, with one and a half days off in every four days. At the start I was given a particular frequency to scan, as I became more experienced in my work I was allowed to scan the airwaves for messages. The majority of the work was routine and I would write the messages in pencil onto a square note pad in block letters. If a message came through that I thought might be urgent or very important I would write the message and pass it straight to my supervisor. Towards the end of the war we knew that the enemy was on the run as the messages started to come through in what we called “plain language”.
I worked until near the end of the war, the beginning of 1945.
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Identifying operators by their 'fingerprints'
Identifying operators by their ‘fingerprints’
When Morse is sent by hand, every operator has his or her own characteristics in the shape of slight variations in the lengths of dots and dashes and spacing between letters and words. Slight as they are, when a Morse operator regularly “works” another operator, it becomes quite easy to recognize the style or “fist” of the other.
In the Second World War, the differences in the sending styles of secret agents were noted by their home stations so that if they were captured false messages emanating from the enemy could easily be detected. The styles of operators on enemy submarines, ships or military units were also identified to help track their movements on a day-to-day basis.
Morse: the end of an era?
Morse: the end of an era?
Tony Smith, consultant Editor of Morsum Magnificat, an international magazine devoted to Morse telegraphy.
From midnight, January 31, 1999, international regulations no longer require ships at sea to be equipped to call for help in an emergency using Morse code and the well-known SOS signal. On February 1, the Global Maritime Distress and Safety System (GMDSS), using satellite and other high-tech communication techniques, replaced a system which since the early part of this century has saved countless ships and thousands of lives.
GMDSS has been developed and progressively implemented since 1979. As more and more ships adopted the new system, coastal radio stations around the world have been closing down their wireless telegraphy (W/T) services as demand has decreased.
As midnight approached on January 31, many of the remaining stations sent their final Morse signals in a profusion of emotional messages, typical of which was this from a group of Danish stations: “Concluding an era of more than 90 years of W/T service from Danish coast stations, starting in 1909. . . . This is the last transmission for ever.”
Thus signed off with dots and dashes the era of Morse telegraphy, a medium which in the 19th century had created a revolution in world communications, serving virtually every aspect of human activity: government, diplomacy, business, industry, railways, newspapers, military, and more, plus the needs of ordinary people who wished to send telegrams.
‘What Hath God Wrought!’
Following the Italian physicist Alessandro Volta’s invention of the voltaic pile in 1800, the first means of storing electricity, there was an upsurge of electrical experimentation, including many attempts to achieve communication between distant points using electricity and metal wires. In 1832, Samuel F.B. Morse, a well-known American artist, conceived the idea of an electromagnetic instrument to achieve this by means of interrupted electrical currents corresponding to a prearranged code (see box).
In 1843, Congress allocated $30,000 to test his invention on a 40-mile (65-km) line along the railroad from Washington to Baltimore. This opened on May 24, 1844, with the sending of the apposite phrase “What Hath God Wrought!”, and within a year private companies came into being with plans to run Morse lines to all parts of America.
In 1866, after several earlier attempts, a submarine cable linked Britain and America. By 1871 a cable had reached Australia, and well before the turn of the century most of the world was covered by a vast network of Morse lines.
A new industry
The Morse telegraph created an entirely new industry which, amongst other things, offered women for the first time an opportunity to take up a respectable career, that of a telegrapher, outside their own homes. Telegrams became a way of life for business and for individuals, and many large organizations had their own telegraph offices.
In 1848, six New York newspapers formed the Associated Press, sharing news-gathering and telegraphic services. They hired their own lines and operating staff, and by 1923 AP landlines across North America totalled 92,000 miles (148,000 km) serving the interests of 1,207 member newspapers.
Many famous people started their careers in the telegraph industry. Thomas Edison, the famous inventor, was an itinerant Morse telegrapher at the age of 17, travelling thousands of miles throughout the United States and Canada, taking job after job as his fancy, or circumstances, dictated.
Andrew Carnegie, the industrialist and philanthropist, began as a messenger boy and was a telegraphist for twelve years. Gene Autry, “the singing cowboy”, who died in 1998 aged 91, was a railroad telegrapher in his youth before he became a Hollywood star.
In the early days of broadcasting, a telegrapher accompanied American commentators to sporting events, and special lines were installed to connect the stadium to the radio station. The telegrapher sent short reports to the station describing the progress of the match, and a “sportscaster” used them to provide a “live” commentary on the game as if he were there personally. One broadcaster who worked in this way in the 1930s was Ronald Reagan, later President of the United States.
A universal code
The code used on the American lines was “American Morse”, which is not the same as the international code we know today. The first Morse line in Europe was between Hamburg and Cuxhaven in 1847, but the American code was not entirely suitable for the German language with its diacritical letters. A new extended code was therefore devised, including some new characters and some retained from the American code.
As the telegraph spread to other German states and to Austria, each state devised its own variation of the Morse code, necessitating telegraphic translation to a different code by an operator as messages crossed state boundaries.
In 1851 the Austro-Germanic Telegraph Union adopted a slightly amended version of the 1847 code for use in all states as part of a unified telegraph system effective from July 1, 1852. The new code spread to other European countries and was finally adopted for universal use in 1865 by the newly formed International Telegraph Union.
Later, some countries developed their own versions of the code for internal communications. Apart from the original American Morse, which remained in use within the United States, there are Arabic, Burmese, Chinese, Greek, Hebrew, Japanese, Korean, Russian, and Turkish Morse codes, and possibly more.
The European code, which finally became the international Morse code, was the chosen communication mode for the newly invented wireless at the end of the 19th century.
A good practical system of signalling already existed between stations using metal wires to carry their signals. The purpose of early wireless was simply to replicate and extend the scope of the Morse telegraph without the need for wires between stations. When wireless was found to be capable of sending messages over great distances it was adapted for use by ships at sea which previously had no means of communication with land, or each other, except by visual signalling when close-by.
Inspiration for wireless
The most famous early use of Morse at sea was when the Titanic struck an iceberg and sank on the night of April 14, 1912. Her two Radio Officers, Jack Phillips and Harold Bride, stayed by their radio until the last moment, sending out CQD SOS messages in Morse code calling other ships to their rescue. “CQD” was a recognized maritime distress signal, and “SOS” was a new international signal due to replace it shortly.
Their calls were heard 58 miles (93 km) away by the Carpathia, which arrived on the scene an hour and twenty minutes after the Titanic sank and rescued some 700 survivors. Over 1,500 people died in the tragedy, including Jack Phillips. Bride survived and although unable to walk or stand, spent much of the time over the next four days heroically helping the radio officer of the Carpathia send a continuous stream of messages from the surviving passengers to their next of kin.
Military use
Morse telegraphy was used by military forces in the Crimean War, and in the American Civil War. In the First World War, it was widely employed in trench warfare with buzzers replacing sounders. At the same time early wireless telegraphy sets were coming into use.
By the time of the Second World War, although wired telegraphy was still used, wireless had become the preferred form of military communication. It was also an essential part of clandestine/ intelligence operations, particularly in occupied Europe where Allied agents risked detection, and their lives, every time they transmitted a message to London. Morse by radio also served as a vital communications link for the greatly increased use of aircraft in wartime operations.
In most armed forces today Morse is no longer taught as a standard form of communication, although some operators still learn it as a special skill. In a recent unusual application, Sudan People’s Liberation Army rebels fighting the government of Sudan have been heard on shortwave radio, without Morse keys, vocalizing the code as “dits” and “dahs” into microphones.
Not quite the end
The invention of radio signalled the beginning of the end for landline Morse, but it took a long time to happen. While long-distance radio services challenged the cable companies, the advent of the teleprinter took a more immediate effect. Britain’s Post Office officially abandoned Morse in 1932, although its use continued in the United States and Australia until the 1960s.
The same process took place in other countries although from time to time unconfirmed reports indicate that landline Morse still survives in Mexico and India.
Morse at sea has officially ceased, but it has not yet disappeared. Some stations and ships are still actively carrying Morse traffic, mostly in the developing world, but some European stations can also be heard. The high cost of installing new equipment in the ships is the main reason for the delay in changing to GMDSS, but also training facilities have not been able to keep up with demand.
There is still one major user of Morse code. Radio amateurs worldwide use it to communicate with each other because of two advantages. It has an internationally understood system of abbreviations which aids communication between people who are unfamiliar with each other’s language; and Morse radio transmission is a particularly effective means of getting signals to distant places compared with other radio modes—the same advantages that made it so valuable for maritime use.
Landline Morse is also kept alive by hobbyists. In America, Canada and Australia, enthusiasts mount historical displays and communicate with each other using original keys and sounders via the public telephone system, dial-up units, and modems.
HEXADECIMAL COLOUR
A hex triplet is a six-digit, three-byte hexadecimal number used in HTML, CSS, SVG, and other computing applications, to represent colors. The bytes represent the red, green and blue components of the color. One byte represents a number in the range 00 to FF (in hexadecimal notation), or 0 to 255 in decimal notation. This represents the least (0) to the most (255) intensity of each of the color components. The hex triplet is formed by concatenating three bytes in hexadecimal notation, in the following order:
- Byte 1: red value (color type red)
- Byte 2: green value (color type green)
- Byte 3: blue value (color type blue)
- : #000000
For example, consider the color where the red/green/blue values are decimal numbers: red=36, green=104, blue=160 (a greyish-blue color). The decimal numbers 36, 104 and 160 are equivalent to the hexadecimal numbers 24, 68 and A0 respectively. The hex triplet is obtained by concatenating the 6 hexadecimal digits together, 2468A0 in this example.
Note that if any one of the three color values is less than 16 (decimal) or 10 (hex), it must be represented with a leading zero so that the triplet always has exactly six digits. For example, the decimal triplet 4, 8, 16 would be represented by the hex digits 04, 08, 10, forming the hex triplet 040810.
The number of colors that can be represented by this system is
An abbreviated, three (hexadecimal) digit form is sometimes used.[5] Expanding this form to the six-digit form is as simple as doubling each digit: 09C becomes 0099CC. This allows each color value to cover its full range from 00 to FF. The three-digit form is described in the CSS specification, not in HTML. As a result, the three digit form in an attribute other than "style" is not interpreted as a valid color in some browsers.[citation needed]
[edit]Converting RGB to hexadecimal
Converting a decimal RGB value to a hexadecimal value is fairly straightforward. RGB values are usually given in the 0-255 range; if they are in the 0-1 range, the values are multiplied by 255 before conversion. This number divided by 16 (integer division; ignoring any remainder) gives us the first hexadecimal digit (between 0 and F, where the letters A to F represent the numbers 10 to 15. See hexadecimal for more details). The remainder gives us the second hexadecimal digit. For instance the RGB value 201 divides into 12 groups of 16, thus the first digit is C. A remainder of 9 gives us the hexadecimal number C9. This process is repeated for each of the three color values. Most modern operating systems have a built-in calculator to perform conversions between number bases and this can also be done with some hand-held calculators. This task can also be carried out using various web resources.[6]
Color Hexadecimal Color Hexadecimal Color Hexadecimal Color Hexadecimal aqua #00FFFF gray (grey) #808080 navy #000080 silver #C0C0C0 black #000000 green #008000 olive #808000 teal #008080 blue #0000FF lime #00FF00 purple #800080 white #FFFFFF fuchsia #FF00FF maroon #800000 red #FF0000 yellow #FFFF00
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This post has taught me how Hex code works for colour. But it does not tell me how the initial coding language works. Hexadecimal is a way of condensing numbers down but what else can it be used for? how is it made up? what is the history of the code? Is it used for anything else?