# Computer Science

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Computer Science

## 2. Computational Logic

### 2.1. Logic Gates

2.1.1. Boolean Notation -

2.1.2. ¬A = NOT

2.1.3. A•B = AND

2.1.4. A+B = OR

## 3. Data Representation

3.1.1. Binary is converted to denary numbers using a conversion table.

3.1.2. Binary Shift is the act of multiplying or dividing a binary number by a multiple of 2.

3.1.3. An overflow error is when a denary number exceeds the highest number in its binary set, e.g. 265 in 8 bit binary.

3.1.4.1. 0 + 0 = 0

3.1.4.2. 0 + 1 = 1

3.1.4.3. 1 + 0 = 1

3.1.4.4. 1 + 1 = 10

3.1.4.5. 1 + 1 + 1 = 11

3.2.1. Hexadecimal is used as a shorter way to represent binary numbers

3.2.2. It uses 1-9, A-F

3.2.3. It is used mainly to represent colours in 8-bit colour depth. (255 red, 255 blue, 255 green)

### 3.3. Check-digit

3.3.1. Check digit is used to highlight corruption when transferring files.

3.3.2. It is also used to check if things like barcodes are legitimate/useable.

### 3.4. Binary

3.4.1. 8 bits = 1 byte

3.4.2. It is represented in 0's & 1's

3.4.3. Very reliable

3.4.4. 4 bits = a nibble

3.4.5. Very easy to represent as electrical signals (on & off)