17.11. REPRESENTING DATA USING BITS (CHARACTERS/TEXT) (2.44)

This is a guide for students attempting Representing Data using Bits in digital technologies achievement standard 1.44 (AS91074). You will need to cover **two**different types of data to meet the requirements of the standard (each assessment guide only covers one). See the introduction for the 2.44 guides for more details on choosing topics; this guide covers the “characters/text” type of data. In order to fully cover the standard, you will also need to have done one more project for representing data using bits and projects covering the topics of *Encoding*and *Human Computer Interaction*, and included these in your report. ## 17.11.1\. OVERVIEW The topic of representing data using bits has the following bullet points in achievement standard 1.44, which this guide covers. Note that there is no excellence criteria for this topic. This assessment guide only covers one of the two types of data required for achieved. **Achieved**: “describing ways in which different types of data can be represented using bits” **Merit**: “comparing and contrasting different ways in which different types of data can be represented using bits and discussing the implications” As with all externally assessed reports, you should base your explanations around personalised examples. ## 17.11.2\. READING FROM THE COMPUTER SCIENCE FIELD GUIDE You should read and work through the interactives in the following sections of the CS Field Guide in order to prepare yourself for the assessed project. Read all of these sections, as they give the necessary introduction of the topic 5.1 - What’s the Big Picture? (General information about bits) 5.2 - Getting Started 5.3 - Representing text with bits 5.7 - General representations of text (Required for Merit) ## 17.11.3\. PROJECT ### 17.11.3.1\. WRITING YOUR REPORT **Achieved** For Achieved, you need to demonstrate that you know how to convert characters into binary numbers. ASCII, which uses 8-bit codes, is a simple system to explore for this. You should show the binary representation for a few characters; the easiest way to do this is to show the ASCII code for your name. Briefly describe the relationship between characters and their ASCII code. A few sentences is fine. **Merit** The most common longer code for characters is Unicode, which actually covers multiple lengths of representations. You could show a conversion to Unicode for the characters in your name, but to contrast the power of Unicode, it’s ideal to show the representation of some characters that wouldn’t be possible in ASCII e.g. choose a Chinese (Simplified Chinese) or Japanese (Kanji) name for a city and explain how the characters would be represented. Discuss why more bits are needed for these character sets. Use your example to discuss the tradeoffs that are made by using a 16-bit character representation, and to explain the limitations of the ASCII code. You could also use the 5-bit Baudot code to contrast different representations of text, and again explain the tradeoffs between this and either ASCII or Unicode. ## 17.11.4\. HINTS FOR SUCCESS * Remember that this part of the standard only goes up to the merit level. While you need to do some evaluation for merit, you should be mindful that the other topics go up to the excellence level, so they should make up the bulk of your in-depth discussions. * Remember to do a second project on a different type of data for the merit level. * Be careful to use personalised examples (i.e. represent words that are personal to you such as your name or street name). ## 17.11.5\. RECOMMENDED NUMBER OF PAGES We recommend that this project does not take up more than 1 page. Examples should be small, and discussions should be short and to the point, keeping in mind that there is no excellence criteria for this topic.