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| Question | Answer |
| Bit(b)=Single binary digit (1 or 0) Nibble = Byte(B) = Kilobyte = Megabyte = Gigabyte= Terabyte = Petabyte = | Single binary digit (1 or 0) 4 bits 8 bits (one character) (1000 bytes) 1000 kilobyte 1000 megabyte 1000 gigabytes 1000 terabytes |
| Name the smallest measure of data? | A bit |
| How many nibbles are there in a byte? | 2 |
| How many terabytes are there in 1 petabyte? | 1000(1024) |
| Calculate the number of megabytes in 15 terabytes. | 15 000 000 MB 15TB * 1000 = 15 000 GB 15 000GB * 1000 = 15000000MB |
| A DVD has 300000 kilobytes of data on it. How many gigabytes is this? | 0.3 GB 300000KB/1000 = 300MB 300MB/1000 = 0.3GB |
| Mei has 3 identical files that have a combined size of 2.1 terabytes. How big is this in gigabytes? | 700 GB 2.1TB/3 = 0.7TB per file, 0.7*1000 = 700 GB |
| Adnan has an external hard drive that can store 500 gigabytes of data. How many 10000 megabyte videos can he store on the external hard drive? | 50 videos 10000MB/1000 = 10GB per video, 500/10 = 50 |
| Which digits are used in the binary number system? | 1 and 0 |
| Why do you need to convert data into binary? | Computers can only process binary data |
| True or False? 4-bit numbers can represent the denary numbers 0-255. | False – 4-bit numbers can only represent 0-15 |
| What is the least significant bit in the binary number 1010? | 0 (the right-most bit) |
| Convert the denary number 7 into binary. | 111 |
| Convert the binary number 00011010 into denary. | 26 |
| What is the largest denary number that can be represented as a 5-bit binary number? | 11111 = 31 |
| Use the table below to convert 118 into 8-bit binary number. | 01110110 |
| What is the result of adding 1 + 1 in binary? | 10 |
| When performing a 1 place left shift, is a binary number doubled or halved? | Doubled |
| If a binary number is shifted 4 places to the right, what is the effect on the size of the number? | The number has been halved four times. |
| What is an overflow error? | An overflow error is when the answer to a binary calculation requires more bits than the CPU was expecting, and the extra digits are not handled correctly. |
| Add the binary numbers 10110100 + 01000101. | 11111001 |
| Use binary shift to multiply the binary number 00101011 by 4. | 10101100 |
| Which letters are used as hexadecimal digits? | A,B,C,D,E,F |
| True or false? Computers can process hexadecimal data. | False – computers can only process binary data |
| What is the denary number 12 in hexadecimal? | c |
| Convert the binary number 1011 into hexadecimal. | Converting to denary: 8+0+2+1=11. The denary number 11 is B in hexadecimal. |
| Convert the hexadecimal value D into binary. | The hexadecimal value D is 13 in denary. 13=8+4+0+1, so 13 is 1101 in binary. |
| Explain why a programmer might prefer to use hexadecimal instead of binary. | Numbers in hexadecimal are a lot shorter than they are in binary. This means that they are much easier for a programmer to read and remember, so less chance of error. |
| Moving from right to left, how do the place values increase in hexadecimal? | They go up in powers of 16 |
| How many bits can represent the same number of values as two hexadecimal digits? | 8 |
| Convert the denary number 167 into hexadecimal using the division method. | 167/16 = 10 remainder 7. 10 in denary is A in hexadecimal, and 7 in denary is 7. |
| Convert the binary number 00111101 to hexadecimal. | Split the number into two nibbles, 0011 and 1101. Convert each nibble into a hexadecimal value – 3D |
| Convert the hexadecimal number 9F to binary. | Convert each hexadecimal digit to denary to get 9 and 15. Convert each denary value into binary values - 10011111 |
| What is a character set? | A character set is a collection of characters that a computer recognises from their binary representation. |
| Which character set is larger, Unicode or ASCII? | Unicode |
| What is the size of a text file (in bits) that uses 8 bits per character and contains 80 characters? | 8 x 80 = 640 bits |
| How does the number of bits used to represent each character in a character set affect the number of characters that can be represented? | The more bits that are used, the more characters that can be represented. |
| In ASCII, the binary code for ‘a’ is 01100001 and ‘b’ is 01100010. What is the binary code for ‘e’ in ASCII? | As the codes for the letters are sequential. b = 01100010, c = 01100011, d = 01100100 and e = 01100101 |
| explain the advantages of Unicode over ASCII | Unicode can represent many characters from different alphabets, which makes it more useful for users writing in a language other than English. Unicode can represent more special symbols, giving more variety in what they can write. |
| What is colour depth? | The number of bits used for each pixel. |
| Calculate how many different colours a 5-bit image can use. | 2⁵ = 32 (2*2*2*2*2) |
| What is the formula that relates file size, image | File size = image resolution*colour depth or width*height*colour depth |
| Give one advantage and one disadvantage of using images with a high resolution. | A higher resolution is likely to give a better-quality image. However, the image will have a large file size which will require more storage space. It would take longer to upload or download from the internet. |
| An image is 10 pixels high, 10 pixels wide and has a colour depth of 4-bits. What is the file size of the image. | File size = width*height*colour depth: 10*10*4 = 400 bits |
| Give three types of information that are often stored in an image’s metadata. | Height and width of image, colour depth, resolution, file format, date/time image taken. |
| What is meant by the term sample rate? | The sample rate is the number of sound samples per second measured in hertz |
| What is the formula to calculate sound file size? | File size = sample rate*bit depth*duration |
| Outline how an analogue sound wave is converted into digital data, and how quality can be lost during the conversion. | The amplitude of the sound wave is measured at regular intervals to create a digital approximation of the sound wave. The amplitude between each measurement is not recorded, causing a loss of quality. |
| How does increasing the sample rate improve the sound quality? | A higher sample rate means samples are taken more often, so less data is lost. This means the digital sound file will be closer to the original. |
| Explain why sound is not always sampled using settings that give the highest possible quality. | Recording a higher quality version will increase the size of the file, which means more storage space will be needed and sending the file across a network will take longer. |
| A 200 second piece of audio is sampled using a sample rate of 30 Hz and a bit depth of 10 bits. What is the file size of the sampled audio? | File size = sample rate x Bit Depth x Duration (Seconds) =30 x 10 x 200 = 60 000 bits |
| What does compressing a file mean? | Reducing the size of a file |
| True or false? Lossless compression temporarily removes data. | True – it restores the data when the file is decompressed |
| Give two benefits of compressing files. | Any two from - compressed files take up less storage space - compressed files are quicker to upload and download - a file might need to be compressed to be sent via email |
| The owner of a website that allows users to stream and download music is deciding which type of compression to use on the music files. Explain the advantages of using lossy compression instead of lossless compression. | Lossy compression will give a greater reduction in file size than lossless compression, so streaming and downloading the music files will be quicker and storing the files on the website’s server will use less storage space. Also, lossy music files like MP3 are more commonly used than lossless formats like FLAC, so more people can play the files. |
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