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Data Computer Science Flowchart - Coggle Diagram
Data Computer Science Flowchart
Data 1
Data is stored in binary, with a finite number of permutations - 2^n combinations if there are n total bits.
File sizes
1 bit, 1 byte = 8 bits, 1 KB = 10^3 Bytes, 1 MB = 10^6 Bytes, 1 GB = 10^9 Bytes, 1 TB = 10^12 Bytes
1 bit, 1 byte = 8 bits, 1 KiB = 2^10 Bytes, 1 MiB = 2^20 Bytes, 1 GiB = 2^30 Bytes, 1 TiB = 2^40 Bytes
Binary is used to represent Number, Text, Sound, Graphics and programs. In general, all data is stored in binary
Binary numbers are represented differently to decimal, in the way that each place-holder is a power of 2 and only 2 digits exist, 1 and 0, off or on.
Overflow occurs when the number of bits accommodated to store a number is not enough to store a number, essentially you cannot store a number like 500 when your bits can only store a maximum of 256. In this process, you cannot store the whole number and lose accuracy/precision.
Two's complement is a process by which we can store a negative and a positive number without having to store 2 zeros. This is done by making the MSB have a negative value when it is 1 and not have a value when it is 0. You can convert a positive 2s complement number to negative and vice versa by flipping all the bits and adding 1.
Binary shifts are essentially means by which you can shift all the bits left and right in a number, and achieve multiplication or division by a power of 2.
Logical Binary shifts are done by shifting all the bits left and right and filling in all the gaps with a zero.
When doing an Arithmetic shift, left shift is the same as the logical left shift and when doing right shift, you replace the MSB with the number that the MSB is rather than simply a 0 in LSR.
Hexadecimal is a number system wherein there are 16 unique digits that can fill a placeholder rather than simply 10 or 2 like denary or binary. It is used for colours in HTML, MAC addresses, Machine code, Debugging memory dumps, as hexadecimal is a bit easier to process than binary for human interpretation, and finally registers in control systems. Each nibble in binary represents 1 hexadecimal digit.
Data 3
An analogue sound has an infinite number of permutations, and this needs to be represented digitally. This is done by ADC (Analogue to Digital Conversion) essentially takes samples of this data in the process of sampling.
The sample rate is the number of sound samples that are taken per second, essentially the sampling frequency. CDs record at a sampling frequency of around 44.1 kHz for a balance of quality and storage.
The more the samples the better the sound, since the gap between the samples is not recorded, and to produce an exact copy of the analogue sound would need need an infinitely high sampling rate.
Bit depth is the number of bits used for each sample, and allows for much smaller gradations in the amplitude of the sound to be recorded, if the depth is too low, then the recording is not accurate and may lose out on a lot of clarity.
Both sampling rate and bit depth need to be balanced, to be able to ensure that the number of samples is high enough and each of a high enough quality. CD operates at 44.1 kHz because of Nyquist's theorem, wherein some of the highest pitch notes can be reproduced at the peaks and troughs.
A sound file size is in bits is given by the sample rate
Bit depth
duration in seconds.
Lossless compression is when data is compressed without losing accuracy or precision. one example of this is RLE or run length encoding, whereas Lossy encoding loses some data, but in many cases data that the human ear cannot recognize or distinguish between.
Data 2
Characters in a computer are stored in binary, but represented for humans in Hexadecimal ASCII. ASCII is a character set which uses 7 bit binary to represent numbers and characters as text. However, 7 bit ASCII lacks the range of characters required for the general public, and so does extended ASCII, hence Unicode is generally used.
Python has 2 main functions which allow for conversion between text and their binary codes. Ord(character) returns an integer that the character is represented by and chr(value) returns the character represented by that value.
A pixel or picture element is the smallest element of a bitmap and for a fixed physical size of an image, the more the more the pixels the sharper the image.
A pixelated image is one where individual images are visible.
Resolution is what according to Edexcel determines the size of an image when it's displayed on a screen. Based on the pixels per inch of an image. An image of 200ppi would mean that 200 pixels are displayed per inch for an image.
Colour depth is the number of bits used to encode an image, the more the number of bits the more the number of colours each pixel can represent,