4.1 Machines and Computational Models GCSE Computer Science - Revision

4.1.1 Computer Hardware Hardware Machine - Computer hardware (or simply hardware in computing contexts) is the collection of physical elements that constitutes a computer system. Computer hardware is the physical parts or components of a computer, such as the monitor, mouse, keyboard, computer data storage, hard disk drive (HDD), graphic cards, sound cards, memory (RAM), motherboard, and so on, all of which are tangible physical objects. By contrast, software is instructions that can be stored and run by hardware. Desktop, Laptop, Smartphone, Tablet, Digital Watch, Washing Machine, Smart TV…etc

4.1.1 Components – Match the cards

4.1.1 Virtual Machine a virtual machine (VM) is an emulation of a particular computer system. Virtual machines operate based on the computer architecture and functions of a real or hypothetical computer. https://www.youtube.com/watch?v=ZmPY9nEFPMk

4.1.1 Virtual Machine - Advantages System virtual machine advantages: Multiple OS environments can co-exist on the same primary hard drive, with a virtual partition that allows sharing of files generated in either. Application provisioning, maintenance, high availability and disaster recovery are inherent in the virtual machine software selected. Can provide emulated hardware environments different from the host's instruction set architecture (ISA), through emulation or by using just-in-time compilation.

4.1.1 Virtual Machine - Disadvantages The main disadvantages of VMs are: A virtual machine is less efficient than an actual machine when it accesses the host hard drive indirectly. When multiple VMs are concurrently running on the hard drive of the actual host, adjunct virtual machines may exhibit a varying and/or unstable performance (speed of execution and malware protection). Malware protections for VMs are not necessarily compatible with the "host", and may require separate software.

4.1.2 System Bus Control Bus - Sends and receives signals that control the CPU and other parts of the computer system. Address Bus - Carries the address of memory locations used to store data and program instructions. The more lines or wires the address bus has the more memory locations can be uniquely identified. Data Bus - Transfers the binary data around the computer, between hardware devices.

4.1.2 Computational Models A sequential computational model is one in which instructions are executed one after another. There may be branches in the program, but the general principle is that each instruction follows on from the previous one. The Python programs pupils have written are sequential. A parallel computational model is one in which each program instruction is executed simultaneously on multiple processors in order to get the results faster. Recall that using multi-cores in processors is an example of parallel computing. It is by using parallel processing that super computers are getting faster and faster. A multi-agent computational model is one in which computer systems co- operate and co-ordinate with other agents to achieve their goals. Swarm robots are examples of multi-agents.

4.1.2 Multi-Agent Models Nano quadrotors http://singularityhub.com/2012/02/05/flying-robotic- swarm-of-nano-quadrotors-gets-millions-of-views-new-company/ Drone brick layers http://www.youtube.com/watch?v=pxLfzWDs3HA Fetching and carrying robots http://www.telegraph.co.uk/science/science-news/9965029/Robot- swarms-trained-to-fetch-and-carry.html Robot football https://www.youtube.com/watch?v=4Y2Cf9nRqOw Recall the video of warehouse robots http://www.youtube.com/watch?v=8gy5tYVR-28

4.1.3 Input-Process-Output Model

What is a Computer System? In Pairs - Now make a list of all the digital devices in your home that have inputs, processors and outputs Computers consist of Input Devices, Output Devices and a Processor Some systems have communications and storage devices but these are optional

4.3.1 Input–Process–Output Model

4.3.1 Input–Process–Output Model

4.1.2 – Multi-Agent Model 4.1.1 – Virtual Machine

4.1.2 – Multi-Agent Model 4.1.1 – Virtual Machine

4.1.3 Input-Process-Output

4.1.3 Input-Process-Output