OK so I was reading this blog entry and I thought to myself “You know some of the higher class might want a crack at that!”. If you fancy creating a skin for our glow group then come and talk to me and we can share some ideas.
Here is a little something to make you think
Today’s lesson was feed back from Tuesday’s short paper.
Please look over the paper and answers. Make sure that you have studied the questions that you did not get full marks on so you can improve your answers in the future.
You can find the papers and answers here
Today we learned all about printers and all the different types that you get, including their cartridges and about different types of screens.
Mr Stratton began by recapping what we had talked about in the previous lessons, cameras, analogue to digital converters, videos etc.
He began the lesson by taking the printer to pieces to show us the cartridge and explained that not all of them contain bombs. Ink-jet printers are based on a mixture of three different types of technology : continuous flow ink-jet, liquid ink jet and phase-change ink-jet. Mr Stratton then went on to explain about how liquid ink-jet works. Liquid ink-jet works by squirting tiny drops of ink onto the paper, the ink is firstly heated up by the electric current through a coil, this creates a bubble which then forces the ink from the printer to the paper.
We then went on to talk about how laser printers work. Mr Stratton went on to explain that the lasers “write” a page image onto a special drum as an electrostatic charge, the charged drum draws the toner particles which then transfers onto the page to make an image.
In today’s lesson we also learned about different types of screens/monitors. We learned that multi-screen monitors are used for desktop computers and are based on technology which is similar to that of a TV screen, these both use a CRT-Cathode Ray Tube. CRT improves the quality of the images on screen. A Cathode Ray Tube is a miniature version of the lights that are in a classroom and are meant to last roughly 10,000 hours but because of the size and different parts required to make it work it turns out to be reasonably complicated and expensive to make. TFT-Thin-Film Transistors are much more robust as they are a lot cheaper to produce and do not take as much time to make. This means that overall it would be practical to use a TFT monitor rather than a CRT just because they are a lot more reasonable in price, however, the CRT is actually better because the screen is brighter and far more realistic.
We then began to have a natter about how TFT screens brake if they are twisted unlike the latest LED screens that are able to be moulded for flexibility. So if you want a laptop that rolls up like a newspaper in your pocket you might want to wait till they are released.
To end the lesson Mr Stratton then began to talk about- “the project“. He spoke about how the old exams used to be and how you could pick your own subject and work away at it, which he loved, and how it has now changed so that we all have to do the same, which he doesn’t really like that much. He also mentioned what he aims to do tomorrow-give out two different projects to the separate groups, tell us to decide what is good and which is bad, give them a mark and then give us the marking scheme= tomorrows lesson.
That’s all folks. 🙂
Today we learned about cameras.
We learned that different types of will have different frame rates. Cheap £20 phones will have very poor video quality. HD video on a phone is better, a digital camera is better than that, a professional camera will be better and a proper TV camera will produce the best quality.
Some cameras have a digital delay.
We also learned that AVI stands for Audi Video Interface. AVI is a windows base format which interleaves video sound and video data.
QuickTime – CODEC was developed by apple but can be used by both Mac and PC. It, like AVI, interleaves sound and video data.
We learned that accurate depends on compression technique, frame rate and resolution.
Speed – Hardware must be fast enough to cope with stream of to memory and to the hard disk.
A digital TV tunes can turn a computer into a digital TV. Good for people who want a computer and TV.
Film replaced by an array of photosensitive cells. Images stored electronically using photosensitive diodes called shared coupled devices (CCDs). The intensity of light is recorded in an image.
Analogue values converted to digital using ADC. Compression usually takes place. Bitmap files are turned into JPEG.
Accuracy is measured in pixels and mega pixels. More is better and less is worse. The accuracy depends on the array of photosensitive cells. The more sensors the smaller they are the higher the resolution.
But depth is in proportion to the number of colours that can be represented. Bit depth is very important on cameras.
Ink is very advanced and difficult to make. That is why it is to expensive.
Inside the pint of a cartage there is a chamber. It is heated and the liquid expands into a bubble. This bubble slowly pops and that is how ink is printed.
Today in Class we learned about scanners and why they are used.
The period started with mr Stratton talking about the previous lesson in which Peripherals mainly the keyboard were discussed.
The Qwerty keyboard has its roots in mechanical typewriters, this type of keyboard was designed in on order to slow down operators in order to avoid jamming the keys.
After a recap on the previous lesson Mr Stratton started discussing with the class about scanners .
A flat bed scanner allows for up to a4 size documents, the document is placed downwards on a glass panel and then scanned, a light beam reflects the light form the document and the photocells measure the light reflected. Also when scanning Analogue data it needs to be converted to digital.
Mr Stratton also told us that Modern Scanners use high bit depths to allow high resolutions.
Furthermore we learned that images that are being scanned must match their purpose meaning that there is no point in scanning at a resolution of more than 75 dpi for a screen based display. Likewise there is no point in scanning at 600 dpi for a printer that is rated at only 300 dpi.
Then we learned about the accuracy of scanners. In scanners accuracy is measured by how close the image is to the original. Resolution was described as the dots per inch (dpi) that can be detected by the scanner hardware.
For example a 600 dpi scanner has 600 photocells per linear inch.
Also the Bit depth of a scanner is usually 24 bits meaning it consists of 8 red bits, 8 green bits and 8 green bits.
Mr Stratton then continued the lesson by teaching us about the capacity of scanners. Such as there is little internal buffering and they rely on different techniques to transfer the data. Also storage can be high for example A4 page at 600 dpi requires 33.28 mb for 8 bit and around 100 MB for full colour.
Then Mr Stratton spoke about the cost of Scanners which have dropped dramatically in recent years and bundles software is often the major selling point.
The towards the end of the period Mr Stratton taught us briefly about sound.
Naturally occuring sound- is analogue in form. To input sound to a computer software samples the incoming signal and then proceeds to convert the signal into digital form and then usually compresses the file.
Then at the end of the lesson we were told to make some music using www.jamstudio.com in order to show us how the process works.
The End!
The lesson began with the talk of yesterday’s lesson. Unfortunately I was not in so I can not comment too much about it.
But pupils had a problem that they could not implement a program, some made the program from scratch which was a waste of time as they could take the program before hand and change this. This is useful as it does not waste time going through a huge code again.
A program was described as Lego. You can build it and then finish it, it may look pretty but you can add pieces or take away pieces to make it a lot more complex and intricate. This idea goes with a program; you can also do this to a program which will make the program better.
The class was introduced to procedures. We had to understand the input and output and this was shown by a structured diagram- which is similar to pseudcode, but is a visual version of it. They can get complex on the other hand which is a disadvantage of using one.
Now using one, every one knows that efficiency is relevant! If we use the same part of a program then we don’t have to keep testing, error checking or even re-writing a program. This saves time and money and makes life easier…the phone went.
To start our structured diagram, we wanted a program that would add 2 numbers together and displayed the answer. It shows each different part of the program using boxes. It looks very similar to a family tree, with the sub-programs expanding down and then along to the right.
Parameter passing consists of a Global Variable (which is a variable which is used throughout the program) and a Local Variable (which is used at one part of the program). The input and output of the program we were writing contains a By Val and a By Ref. By Val is a copy of the variable (read only). And a By Ref is the actual variable (read + write) which can be changed at any time.
An example of parameter passing
1) Set up variables (BY REF)
Output NumA, NumB
2) Get 2 numbers
Input/Output NumA, NumB
3) Display Answer (BY VAL)
Input NumA, NumB
The phone wrung one last time before we left.
By Corrie 😛 x
Design a program that displays a times table that the user enters.
Design MUST have data flow indicated.
Option Explicit
Private Sub Command1_Click()
‘Set up variables
Dim NumA As Single
Dim NumB As Single
Call Get2Numbers(NumA, NumB)
Call DisplaySum(NumA, NumB)
End Sub
Sub Get2Numbers(ByRef NumA, ByRef NumB)
NumA = InputBox(“What is the first number”)
NumB = InputBox(“What is the second number”)
End Sub
Sub DisplaySum(ByVal NumA, ByVal NumB)
MsgBox (NumA + NumB)
End Sub
We were given the following program specification.
Write a program that generates 50 random whole numbers between 1 and 50. display them in a list box in reverse order.
First we need to create the main steps. You should ALWAYS do this for any program specification’s that your given. It makes the task much easier.
Main Steps:
1. Set up variables
2. populate list
3. reverse list
4. display list
5. End program
We have already donesteps 2 and 4 last week. So we did not need the refinements for step 4, but were given the refinements for steps 2 and 3
Ref Step 2.
2.1 For 50 numbers
2.2 create a random number between 1 and 20
2.3 Store this number in the array
2.4 Next Number
The VB code for these steps are:
For Intcounter = 1 to 50
Intnumber = Int(Rnd*20)+1
Intarray(Intcounter) = Intnumber
Next
This code creates 50 random numbers.
Ref Step 3:
3.1 For all 50 numbers.
3.2 Copy item at next position to new array.
3.3 Next
The VB code for these refinements are.
For Intcounter = 1 to 50
Intbackwards(Intcounter) = IntArray(51-Intcounter)
Next
This VB coding takes the random numbers generated and displays them in reverse order. The part of the code thats in Italics, is the peice of code that does this. If Intcounter = 1, then the position of IntArray thats being displayed first would be (51-1) and would display the 50th position. If the counter was 2, the 49th position would be displayed etc, if it was 3 then position 48 etc.
We used a list box to display these numbers. The reason we used a list box rather than just print it onto the form is that it is easier to read due to the scroll option that the list box provides.
We were given the new notes on the topic and started off by discussing the various devices that can be used on computers today thanks to the standardization of the interfaces the various manufactures. We then discussed the various aspects of keyboards and learned how we could make an educated guess of which would be best to suit our needs. On the subject of keyboards we agreed on the layout, hotkeys, number of keys, interface, durability/robustness, physical size, accuracy and price were all important contributing factors that you would need to consider when buying a keyboard. We also reviewed the blog from last week and then discussed the fastest method of typing/texting. We then learned that the keys used most often are positioned on the left hand side of the keyboard in the layout design called ‘QWERTY’ which was created to work with typewriters as only one arm of the old machine could be operational at the one time so a way was made to slow typists down so they would not jam the machine. This layout is not the only one available but it is the one we are used to although not the fastest. For notes on keyboards go to page 77 and 78 of the new notes. Keyboards work by a matrix of wires (a criss-cross pattern) which work by using coordinates to define which key is what. We discussed what type of keyboards are available to buy like; ultra small, infrared, LED buttons, left or right handed or hand typing and virtual keyboards. You can also get modified keyboards. How a keyboard works on page 78. Additionally we started on scanners and discussed how they work. Notes on this part are on page 80.
