Unit 4. Computer Systems

4.1 Computer Architectures

• Every device has primary memory. Primary memory is hardware that the CPU processes directly. There are two types of primary memory - ROM (Read Only Memory) and RAM (Random Access Memory).

• RAM is a piece of hardware that stores data temporarily. It is volatile storage and the data stored in it is constantly changing. It needs the computer to be on and connected to power otherwise any data will not be saved.

• ROM stores data permanently and usually does not change. It is non volatile storage and the computer does not need to be connected to power. The data stored in the ROM does not change because the computer needs the same instructions to us eevery time the computer is turned on.

4.2 Types of Computer Storage

• An operating system is an example of computer system software. It allows you to interact with the hardware of the computer and to run applications, like Microsoft Windows and MacOS.

• An operating system helps with managing input and output, providing a user interface, and managing memory, files and application software.

• The interface is the method used to communicate with the computer, with all the icons, windows, tools and buttons we see.

• The operating system manages the movement of data between the memory and the CPU. The operating system also allows different user accounts to be created for different purposes. It also allows people to keep their accounts safe by setting passwords. It allows people to create and manage files and run application software.

• The operating system also manages input and output devices, and the data transferred between.

• One example of system software is utility software which helps maintain the computer and make sure that everything is running properly by doing things like reorganising disarranged fragments of data, called defragmentation. It can find programs that haven’t been used in a long time and ask users if they want to remove them.

4.3 Data Representation

• When a computer converts text to binary it uses a character set, or a standard set of symbols used to represent binary values. ASCII is an example of a character set that uses 7 digits to represent each letter or symbol. Extended ASCII can be used for different languages and uses 8 digits so it can represent 256 characters.

• Autonomous programming is when AI collects data from a given situation or scenario and uses the data to output a solution and make decisions to produce an output without human control. Data is captured using sensors, an input device that captures data readings from the environment around it. This all happens without any human interaction which makes it fast and effective. The new Mars rover uses AI and autonomous programming to find out where obstacles are and make its way around the planet safely.

• Data compression can help reduce the size of large files by changing the file or changing the way that the file is stored. For example the words can be stored in a table so that repeated words are only marked with the number of times they were repeated and the position, which takes less space.

4.4 Logic gates and truth tables

• A truth table is a visual representation of all the outcomes that can result from a logic gate.

• The logic gates are AND, NOT and OR.

4.5 Augmented Reality and AI

• Some AI systems have the ability to learn and process the data they receive and learn from it, adapting its own rules as a result. This is called machine learning.

• To augment something means to make it bigger, better and more effective by adding things to it. Augmented reality is when you look at something through a device and see computer-generated additions to it.