### Archive

Archive for February, 2013

## cahsee math practise test

February 28th, 2013

The CAHSEE stands for California High School Exit Examination. The mathematics part of the CAHSEE is important section and consists of 6 broad categories more popularly called strands. The Cahsee math test consists of 53 tests divided into these 6 categories.

 Category Details Number of Questions Number Sense Understanding of numbers and ways they are represented 14 Statistics, Data Analysis, Probability (PS) Determine ways to collect, analyze, organize, and display data 12 Algebra and Functions (AF) estimate and calculate measurements for the length, area, and volume of geometric figures; understand scaling in scale drawings and how changes in linear dimension affect area and volume; and solve problems involving dimensional analysis and conversion from one unit to another. 17 Measurement and Geometry (MG) estimate and calculate measurements for the length, area, and volume of geometric figures; understand scaling in scale drawings and how changes in linear dimension affect area and volume; and solve problems involving dimensional analysis and conversion from one unit to another. 17 Mathematical Reasoning Analyze problems, use inductive and deductive reasoning, evaluate the reasonableness of solutio ns, generalize results, and apply them to new problems. 8 Algebra I calculate with symbols and demonstrate symbolic reasoning. 12

Reference Designer have takes steps to make students familiar with these tests. We have started work on the Practice tests. Students can now access cahsee the practice tests online here .

## SAT Math practice test online

February 26th, 2013

Reference Designer, have ventured into education field. We are happy to state that we have extended the tutorials for SAT as well. Starting today, we have the SAT Math practice tests available. You can check out the practice tests here. We will have a lot of study material as well as tips and techniques for success in SAT coming soon.

The SAT material will come in three parts. First the individual lessons itself. Second, the practice tests for the lessons itself. And finally the practice test for the whole course. The best way to learn is to read a lesson and then go through the practice test of THAT lesson. The key to the learning is to learn the chapter again if you made any mistake in any of the practice tests. And possibly take the test again.

We strongly hope that you will have a lot to learn with this study material and lessons. Though we have started with mathematics, we will be bringing more subject matter soon.

## New Javascript Framework Tutorials added

February 23rd, 2013

Encouraged by the positive responses of our javascript and the jQuery tutorial, we have added some more javascript framework tutorials. One of the good things about these tutorials is the ability to make changes in the code and see the results online. We think that the best way to learn is by practicing on the examples, making changes in them and see what happens if.

It is in this background that we have added the following tutorials.

1. Prototype Tutorial

The prototype is a rather old javascript framework, and is slowly loosing its relevant with the advent of the jQuery. However, many older sites still use the Prototype, and you may need to refer it in case you come across it. Hence the Prototype Tutorial. For now there are only two pages but more is coming.

2. Ext JS Tutorial

ExtJS is a professional javascript framework which is gaining ground with support of a lot of graphics elements. If you are looking for developing a cloud application with lots of graphics, the Ext JS tutorial will come handy.

3. Dojo Tutorial

Dojo is still another framework, which may surprise you with the functionality it provides. It is almost as popular as the jQuery and is widely used. Check the Dojo Tutorial here.

We look forward to your comments and descrepencies in these tutorials. Any suggestions for improvement will be highly appreciated.

## Line Break Removal Tool

February 21st, 2013

This is was created out of sheer necessity. We were trying to post some contents from one of the pdfs to a website. We were able to copy the contents from the pdf and able to paste it. However, when we pasted the content, it happened that the lines were broken. We wanted continuous text that will end in paragraphs.

The existing online tools for Removing new lines had one problem - if you copy the complete content, it will remove the new lines or the line breaks, but will also remove any differentiation between paragraphs.

We have improved upon this. What we have done is - ability yo copy one paragraph at a time and the tool will preserve the paragraphs but not the line breaks. In the end it seemed to be very useful and we hope that it will be useful for you too.

You can find the tool here - http://www.referencedesigner.com/remove_line_break/remove_line-break.php

The only limitation it has is that it will not be able to differentiate between a new paragraph and the new line. So you will need to enter one paragraph at a time and it will do the rest. It is better that the other tools which will not be able to do it at all.

Try it and let us know your feedback.

## How Raspberry Pi could have improved

February 13th, 2013

While the designers have done a good job in the hardware design of the Raspberry Pi, there are may things they could have done better. We will capture most important of these.

1. LAN9514 in place of LAN9412

R. Pi uses the SMSC LAN9512 chip, which is a USB hub with Ethernet. Basically you get an ethernet and two USBs. The two USBs are used up easily for a mouse and keyboard. So what if you need a third USB for, say, wifi ? You are out of luck. A separate USB hub is a bad solution. They could have easily improved it by using LAN9514 in place of LAN9512 which provides 4 USBs in place of 2 USBs. You could use a mouse, a keyboard and still be left with two spare ports.

2. Composite Video not needed

Who needs Composite Video ? Looking forward, HDMI is the de facto standard for display and it is great that we have a HDMI connector. Buy who needs the composite video ? This connector is not required at all. Instead, we could place a dual height USB connector. These USB Connectors could possibly point inside ( or outside) and could make a good case of Wifi without the need of a USB Hub.

3. 2x13 pin Connector could be 2 mm pitch

The GPIO pins, serial pins are stacked as two rows of 13 pins each. The pitch of these pins is 0.1" or 2.54 mm. While this is a standard separation, we could easily opt for 2 mm pitch, another standard which is at least as widely used as 0.1". This could have given us at least 12*0.54 = over 6 mm of extra space - enough for another 2 x 3 pins. So instead of the 26 pins we could have 32 Pins. So what will we use these extra pins for ? That brings us to 4th point.

4. More Serial Port and GPIO / USB

The R.
The existing R.Pi has only one Serial port, which is used for console. If you need to use a serial port, then the console needs to be disabled. The Broadcom procesor does support at least one additional serial port, but R.Pi did not bring it outside. With the extra 6 pins, we could easily bring an additional serial port. Also we could use the 4 remaining extra pins, either for USB or for more GPIO, or some other things of our choice.

5. Ethernet Link LEDs not required

They could have instead used one of these LEDs hooked up to a GPIO for learning and general purpose. There are Ethernet connectors that come with LEDs, if they were interested in Ethernet related LEDs. My experience it, ethernet LEDs are rarely used, except during design diagnosis.

6. Switching Regulators to improve current consumption

The previous 4 option, I am 100% sure, would have made R.Pi a better pi. I am not sure about this one. R. Pi has done a great job in power design by choosing low cost ON Semi linear regulators. On side effect is that the power is lost in 5V to 3.3V and then 3.3V to 2.5V conversion. By using a switching regulator, it could reduce the current consumption to well within the limit of 400 mA ( currently it is around 470 mA). But again, I am not complaining about it. The switching regulator, increases cost, requires more board space and the gain possibly offsets the losses.

## Current Consumption in Raspberry Pi

February 12th, 2013

Raspberry Pi comes into two configurations the Type A and Type B. The power is supplied to the raspberry Pi board via the USB connector. Typically a power supply with current capacity of 700 mA or more is recommended.

We set out to measure the actual power consumed by the raspberry Pi. We took a USB cable and cut it from the center. This exposed four wires - we are here concerned with the red and the black ones - which correspond to the 5V and the ground. A bench power supply ( BK Precision 1630) was used, precisely set at 5.0V.

We connected the power supply to the board and powered it up with USB mouse and a keyboard connected. The current observed while browsing the network using midori browser was found to be 0.42 Amperes.

The current consumption as shown in the meter varied between 0.39 Amp to 0.47 Amp.

Although it looks like it is under 500 mA rating of the USB, we would like to mention that, this is only the steady state current. The peak current requirement for the board can actually shoot higher than 500 mA and the USB port, if you happen to power it by Laptop MAY trip.

If you are looking for Raspberry Pi tutorial, you may check this one.