@?computing

What is a summary of encryption?? A way of making sure data cannot be understood if you don’t possess the means to decrypt it. What is a Ceasar cipher?? A method of encryption where you shift the letters along by a consistent amount. What is a brute-force attack?? Where you attempt every possible key to decrypt ciphertext until one works. What is another name for a one-time pad?? A Vernam cipher What is another name for a Vernam cipher?

Why is compression needed?? Because data is constantly being moved around computer systems and networks so a smaller amount of data can be beneficial. What are the two types of comression?? Lossy Lossless What’s an example of a lossy image compression format?? JPG What’s an example of a lossy music compression format?? MP3 What is the definition of run length encoding?? A basic method of compression that summarises consecutive patterns of the same default.

What does MIDI stand for?? Musical Instrument Digital Interface What is the difference between a live recording and MIDI?? Midi is recording a synthesised sound. What is the advantage of MIDI?? Full sound signal doesn’t need to be transmitted, only instructions to play the sound. If vector graphics are the instructions to draw an image, MIDI is?? The instructions to make a sound. Backlinks [[Computing - Syllabus]]S Metadata date: 2020-10-15 11:30 tags: - '@?

What is the main difference between an analogue and digital signal?? Analogue signals are continuous while digital signals are discrete. In one sentence, how does a digital-to-analogue converter for sound work?? Sound is captured by a microphone which is sampled at regular intervals and these samples are converted to binary. The frequency at which samples of a sound are taken is called?? The sampling rate. When an analogue sound signal is being converted to digital, what value is sampled?

In one sentence, how does a camera work?? Approximating a real image by cutting it up into a grid using a light sensor. How is the grid of colour converted into binary in a camera?? Using an analogue-to-digital converter. What is a bitmap?? A grid of pixels. What’s another word for raster graphics?? Bitmap graphics. What is a common bitmap file type?? BMP JPG GIF PNG TIF What is special about a BMP file?

In summary, what are the three things a processor does?? Controls instructions Calculates instructions Executes instructions What is the ALU?? The Arithmetic-Logic Unit What is the CU?? The Control Unit How could you describe the ALU?? The problem solving part of the processor. What’s an example of the arithmetic operations?? Add Subtract Multiply Divide What’s an example of logical operations?? AND OR NOT XOR What’s an example of a shift operation?

What is the binary number $01011011$ in hexadecimal?? $5B$. What is the nibble $0010$ in hexadecimal?? $2$. What is the nibble $1010$ in hexadecimal?? $A$. What is signed binary?? Where the most significant bit indicated whether the number is positive. In signed binary, what does a $1$ sign bit represent?? The number is negative. In signed binary, what does a $0$ sign bit represent?? The number is positive. What is $10010100$ signing bit?? $1$. Is the signed binary number $10010100$ positive or negative?

Data Representation. Backlinks [[Computing - Syllabus]]S Metadata date: 2020-10-06 10:09 tags: - '@?computing' - '@?school' - '@?public' - '@?safe-to-post-online' title: Computing - Data Representation

What is a queue?? A dynamic data structure in which items join at the back and leave at the front. Why is a queue a dynamic data structure?? Because it can contain a variable amount of data. Is a queue FIFO or LIFO?? FIFO. What does FIFO stand for?? First in first out. What is dequeueing?? Where an item is removed from the queue. What is enqueueing?? Where an item is added to the queue.

What is a register?? A temporary storage area in a CPU. Simple computers have an accumulator, more complex computers have…?? Registers. What does LDR Rd, (memory ref) do?? Load the value stored in (memory ref) into register d. How many arguments does LDR take?? 2 I want to put a value at a memory address into a register. What instruction should I use?? LDR. What does LDR R1,300 do?? Load the contents of address 300 into R1.

What are the two types of architecture in computers?? von Neumann Havard Which computer architecture in the most common?? von Neumann architecture. What is the von Neumann architecture? Where instructions and data are stored in a common main memory and transferred using a single shared bus. What is the Havard architecture?? Where instructions and data are stored in two seperate memories and each has a bus. What is the main issue with von Neumann architecture?

What is a computer system?? Any device that can take a set of inputs and process them into useful outputs. What are the three key stages in a computer system?? $$ \text{input} \to \text{process} \to \text{output} $$ What are the 4 main components of a motherboard?? CPU Main memory Address, control and data buses I/O controllers How do components of a motherboard communicate with one another?? Using a bus. What are the three types of bus?