MindMap Gallery Computing MAP GCSE-Computer systems
Computer systems have become an integral part of our modern world, revolutionizing the way we work, communicate, and live. In this mind map, we will explore the components and functions of computer systems, as well as their impact on various aspects of our lives. By the end of this mind map, you will have a comprehensive understanding of computer systems and you will gain insights into the fundamental principles that drive computer technology and how it continues to shape our world in profound ways.
Edited at 2022-10-20 15:50:33Computer systems have become an integral part of our modern world, revolutionizing the way we work, communicate, and live. In this mind map, we will explore the components and functions of computer systems, as well as their impact on various aspects of our lives. By the end of this mind map, you will have a comprehensive understanding of computer systems and you will gain insights into the fundamental principles that drive computer technology and how it continues to shape our world in profound ways.
Computer systems are complex, interconnected systems that encompass hardware, software, networks, and data to perform a wide range of tasks. They are fundamental to modern society, used in businesses, education, healthcare, entertainment, and many other sectors. Computer systems can range from personal computers and smartphones to large-scale data centers and cloud computing infrastructure.
Computer systems have become an integral part of our modern world, revolutionizing the way we work, communicate, and live. In this mind map, we will explore the components and functions of computer systems, as well as their impact on various aspects of our lives. By the end of this mind map, you will have a comprehensive understanding of computer systems and you will gain insights into the fundamental principles that drive computer technology and how it continues to shape our world in profound ways.
Computer systems are complex, interconnected systems that encompass hardware, software, networks, and data to perform a wide range of tasks. They are fundamental to modern society, used in businesses, education, healthcare, entertainment, and many other sectors. Computer systems can range from personal computers and smartphones to large-scale data centers and cloud computing infrastructure.
Component 1: Computer Systems
The CPU
Von Neumman Architecture
- Control Unit (CU): Manages FDE cycle - Program Counter (PC) : holds memory address of each instruction, continuously incrementing. - ALU: Does calculations (+,-,/,*,AND...) - Accumulator stores values outputted by ALU -Registers: - Memory Address Register (MAR) holds memory address about to be used by CPU -Memory Data Register (MDR) holds the actual data either fetched from memory or waiting to be written to memory
FDE Cycle: 1. Fetch: Memory address from PC to MAR. MAr to MDR. PC increment +1 2. Decode: Decoded by CU, CU prepares for next step by loading values into MAR/MDR 3. Execute: Instruction performed (load data from memory, do calculation, write data to memory etc)
Memory
Cache: Faster than RAM, slower than registers Stores frequently used data, so CPU can access quickly when needed (otherwise fetched from RAM) 3 levels: L1, L2, L3 - L1 is quicest but lowest capscity, L3 is slowest but biggest capacity
RAM: "Random Access Memory" High speed, volatile memory (so data is lost whencomputer powered off) Can be read and written to When a computer boots up, OS copied from secondary storage to RAM More RAM generally better
ROM: "Read only memory" Non volatile, can only be written to Bootsrap+BIOS (Basic Input Output System)
Virtual memory: RAm to Virtual Memory (in secondary storage) Used when RAM is too small to handle users requests If CPU needs data again, virtual memory to RAM by swapping, which takes time switching between applications
Performance
Clock Speed: Number of instructions a single prcessor can carry out per second (Hz) Bigger clockspeed means more instructions carried out per second Overclocking makes computer run at a higher clockspeeed than factory set BUT computer can overheat, crash, permanent damage so cooling systems often used)
Number of cores: Each core processes data independantly More cores = more instructions able to carry out Quad core = 4 cores, Dual core = 2 cores (say this) Problem: some software isn't designed to use multicore processing, some processes depend on others, so one core may be waiting for the other to catch up *More cores not always better
Cache Size: A larger cache gives the computer faster accesss to more data it needs to process
Secondary Storage: Non Volatile, RW speeds slower than primary storage eg RAM
Magnetic Storage: Greatest storage, lowest cost per GB Not portable, moving parts so damage risk Used by large organisations Comes in plastic cassettes or disks Disk spins around, tracks and sectors are either magentsied (1) or not (0) RW arm over disk (Actuator) to get/set magnetic charge
Optical Storage: Use light to store data, by burning into disk, restart needs a whole layer burnt off Pit = 0, Land = 1 (land has reflection) cheap, portable, little space taken up Slow write speed, damaged/scratched easily, less storage capacity (blu ray up to 50GB)
SSD: Solid State Drives: Non volatile flash memory used Fast RW times, durable as no moving parts More expensive than magnetic disks but same storage Electrons either charged/trapped (0) or not (1)
Units
Binary is Base 2 8-bit numbers (0 and 1) B->D: Make a table: 128|64|32|16|8|4|2|1 and then write 0 and 1 values underneath then add D->B: make table and go from left to right subtracting numbers, eg 79 would be 64,7,4,2,1 to get to 0.
Binary Addition: 1+1 = 0 carry 1 1+1+1 = 1 carry 1 you can get overflow of most significant value, and loss of data
Binary Shifts: Left Shift multiplies x2 each time its shifted (so 3 shifts is 2x2x2 = 8) Right shift divides by 2 each shift When calculating, fill gaps with 0s
Hexadecimal: 1-9 = 1-9, 10-15 = A-F H->D: 87 = 8x16 + 7x1 when you make table : 16|1 D->H: 106: 106/16 = 6 r 10 = 6A H->B: turn hex to denary then use tables: 8|4|2|1 8|4|2|1 B->H: use tables: 8|4|2|1 8|4|2|1 to get denary then turn to binary
Data Storage
Characters: Character sets are collections of characters that a computer recognises from their binary representation Eg Ascii
Storing Images: Images stored as Pixels Number of colours in an image = number fo bits So B&W will have 1 bit, either 0 or 1 so 2 colours 2 bit image = 00,01,11,10 so 4 colours Total number of colurs = 2 to the power of n, (n=bits per pixel, bpp) File size (in bits) = image resolutuion (widthxheight) x colour depth Metadata is data about data
Storing Sound: recorded by a microphone as analogue, continually changing. Digital is read by computers, sodata is converted by an analouge to digital converter (ADC), this processs is called sampling Digital accuracy can be improved 9matched closer to analogue) by increasing sample rate (taking samples more regularly) File size = sample rate (Hz) x bit depth x length higher sample rate = bigger file size
Compression: Smaller files take up less storage, streaming quiker (less bandwidth needed), web pages load quicker
Lossy: Permanently removes data from file to compressit. Commonly used. Takes up less bandwidth. Loses data, cant be used on text or software files as they need to retain all info. lossy files are worse quality than original (rarely noticeable)
Lossless: No reduction in quality. Can be decompressed to return to normal. can be used on text/software files Slight reduction in file size, not as much as lossless.
Networks
LAN: local area network spans a small geographical area less than a mile. Infrastructure owned by organisation, relatively cheap WAN: Wide area network, connects LANS (internet). businesses would hire organisations to wire it, too expensive otherwise. WAN connected by satelite/ radio links, telephone lines
Factors affecting Network Performance: Bandwidth: the amount of data that can be transferred in a given time Wired wuicker than wireless, wirelesss depends on range +signal quality
Hardware: NIC allows device to connect to a network Switches connect devices on a lan Routers transmit data between networks Wired ethernet connections (Cat 5e and 6) are twisted pair of 4 copper wires. fibre optic cables transmit light. high performance and expensive Blutooth is a direct connection between 2 devices, 10m range so used for headphones Wi-Fi Can be used by many devices connected to a LAN at the same time. 40m-100m range so used in homes. Higher bandwidth vs BT
Client-Server Model Managed by a server, files/software stored centrally Clients send requests to server, server responds Easy to keep track of files, easy to backup, easy to manage network security, reliable and always on servers Expensive, need IT specialist, server dependant, server can become overloaded
Peer-to-Peer Model Networks are equal, connect directly (no server) Store files on individual devices rather than server Easy to maintain, no server dependance No centralised management, copying files creates duplicates, peer machines are less reliable as data is lost if one fails, machines slow down when other devies cross them, harder to do backups
The Internet: Domain Name Server (DNS) translates websites domains names into IP addresses so we dont need to remember Ip addresses
Hosting is when a business uses its servers to store files of another organisation The Cloud: Pros: Users can access files from any device, easy to increase storage availability, no need for exclusive hardware, no IT staff needed, cloud software auto updates Cons: need internet connection, host dependant, all infon vulnerable to hackers, uncear who owns it all, subscription fees could be expensive
Network Topologies
Star Topology: All devices connected to central switch/server If one device fails, ret of network is unaffected. better peformance as data goes straight to a central device, few data collisions (unlike bus topology)
Mesh Topology: Decentralised, all deviced connected to each other. No single point of network failure, if a network fails, data takes different route Partial mesh: not all devices fully connected Both expensive, used in the army
Network Protocols
A network protocol is a set of rules used to govern communication and is therefore used to define rules for data transmission over a network (eg speed of transmission)
Addressses MAC: 16 bit chunks separated by a colon (:) IPV4 uses 32 bits, so 4 billion adresses, IPV6 has 128 bits
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Network Security + Safety
Attack types: Passive: someone moniters data, using packet sniffers Active: someone attacks with malware Insider attack: Someone in an organisation exploits their network access Brute force attack: USe automated software to trial and error passwords Denial of service attack (Dos): hacker floods derver with useless info. making network slow DDoS: distributed DDos, many hackers, infect computers which are then called "zombies" SQL Injections: when a malicious SQL query (command) is entered into a data input box, insecure websites will allow access to private info.
Malware types: Scareware - scares owner Ransomware: encypte=s files unless large money sum is payed Spyware: Records users key strokes Viruses attatch by copying themsleves to files Worms attatch by self replicating, spread quickly Trojans are malware desquised as legitimate software.
People are often easy targets, hackers call them to get access by tricking them, or phishing emails. Can spot by anti-fishing, or grammar checing as they are often poorly written
Safety: Organisations should: regularly test the network, use passwords, install antimalware and firewalls, encyption
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