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Sreeja- Sir, What is a mechanical typewriter? Teacher- The first typewriter had its letters on the end of rods called "typebars." The typebars hung in a circle. The roller which held the paper sat over this circle, and when a key was pressed, a typebar would swing up to hit the paper from underneath. If two typebars were near each other in the circle, they would tend to clash into each other when typed in succession. Radha- But how would the typebars clash? Teacher- Here is the problem. The typebars were attached to the circumference of a metal ring, forming a "basket". When a key was pressed, the corresponding typebar would swing upwards, causing the print head to strike at the center of the ring. Gravity would then return the typebar to its initial position. Radha- It is a great mechanism. If the bars are separate from each other then why would they collide? Teacher- Now look at the above diagram of type bars. And draw the movement of the type bars when you type the letter “FEED”. Now when the type bar for F is coming back to its position E is going to hit the paper. And when E is returning D would be moving. Considering that they are mechanical rods of average precision they will hit each other easily. Imran- How did Sholes solve this problem? Teacher- Sholes was very intelligent and great at problem solving. He understood the problem is occurring due to following reasons.
Ÿ The precision of the typebars are not too good Ÿ Arrangement of keys make adjacent bars hit each other too often
Ÿ The arrangement is too simple and typist can type faster
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Radha- What did Sholes do then? Teacher- Let's try and solve this problem like Sholes did. Imran- Ok, the first one is to deal with precision. But can he increase the precision? Teacher- No, at that time there was no way to improve the precision. Sreeja- So the next option is with the arrangement. He can do something about the arrangement. Teacher- Exactly, Sholes made a list of all frequently appearing combination of letters in the English language and after studying them, came up with a new layout. The objective of this layout was to place these letters far apart on the keyboard thus preventing the type bars from getting entangled. Radha- But didn't initially the users get confused with this new arrangement? Teacher- Yes they did, like you were in the computer lab. But QWERTY keypad was disturbed the alphabetical sequence of letters so that the typists took a longer time to look for each letter, slowing down the speed of typing, in the process. Sreeja- A lesser speed meant fewer chances of the adjacent type bars getting jammed and his third problem is solved! Teacher- Brilliant Sreeja! You got it. Irfan- But why the keyboards are still in a QWERTY format if we are not using the mechanical technique anymore? Teacher- The electric typewriters were then replaced by electronic typewriters which were ultimately evolved into type ball introduced by IBM in 1964. And they gradually evolved in to computer based word processor. And now a day the keyboard doesn't have the type bars which will hit each other during typing. But we are still using the QWERTY model. The journey of typewriter evolution is one of the most interesting evolutions as it ultimately helped into the evolution of one of the most ingenious inventions “The Computer”.
making the bars move to fast and jam.
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IKEN SCIENTIFICA 2011 | PREPARATORY BOOKLET | LEVEL 2
IKEN SCIENTIFICA 2011 | PREPARATORY BOOKLET | LEVEL 2
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