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comp 1 (Algorithms and
programming techniques (an algorithm is when…
comp 1
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system software
System software is a type of computer program that is designed to run a computer's hardware and application programs.
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system architecture
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The Central Processing Unit (CPU) is the component of the computer that controls the other devices, executes the instructions and processes data
embedded systems
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Embedded systems are computers built into other devices like dishwashers, microwaves and TVs.
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Embedded systems are often used as control systems – they monitor and control machinery in order to achieve a desired result. E.g. in an oven – controlling the temperature
They are easier to design, cheaper to produce and more efficient at doing their task
performance
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Clock Speed
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The higher the clock speed, the greater the number of instructions per second
Overclocking = making a PC go faster than its factory settings… risky as processors can overheat causing crashes & permanent damage without sophisticated cooling systems
virtual memory
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Virtual memory is much slower than main memory because processing power is being taken up by moving data around
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Swapping (also called paging) is the process the OS uses to move data between RAM and virtual memory.The OS moves data from processes that are not immediately needed out of the RAM and stores them in virtual memory. It copies the data back into RAM when the process is needed again.
Using virtual memory slows the computer down because copying to a hard disk takes much longer than reading and writing RAM.
network protocols
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IP Addresses
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Just like each network card will have a MAC addresses, every computer on a network will have an IP address.
an IP address is not hard coded into the computer. It can change and is therefore said to be dynamic.
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Ethics and law
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hacking
this means any activity which makes unusual use of, or attempts to break, a computer system.
Hacking can be used for negative purposes such as looking for weaknesses in systems to access and steal private data
it can also be used for positive purposes such as working around bugs in code or exposing security risks in software and websites.
Hackers who attempt to do good through hacking are called white hats but those that carry out criminal activity are called black hats.
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Translators
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An interpreter translates code into machine code, instruction by instruction
Memory
facts
memory and storage are very different, programs are stored on the storage than copied on to the memory to be used
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types of memory
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ram
ram stands for random access memory it is used for storing instructions whilst the program is being used
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units
1 bit = the value of 0 or 1.
8 bits = 1 byte.
1024 bytes = 1 kilobyte.
1024 kilobytes = 1 megabyte.
1024 megabytes = 1 gigabyte.
1024 gigabytes = 1 terabyte.
1024 terabytes = 1 petabyte.
system security
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types of attack
DOS (denial of service) is where the system is forced into a state where services are unavailable or significantly degraded.
corruption of programs or data is when the data in the system is modified in an unauthorized way making the file damaged or unusable.
disclosure of information is where private information like bank details or private emails is extracted and exposed
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security
malware
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Viruses
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Standard Virus
These hide in files / programs and replicate themselves in order to spread into other programs / files. Their aim is usually to delete or damage data.
prevention
penetration testing
‘Penetration Testing’ is where a company will invite / employ experts to try to simulate a range of network attacks such as Denial of Service attacks (DoS), SQL injections and Brute Force Attacks.
They will attempt to discover any weaknesses in the system and will summarise their findings to the company who will then make improvements to their system security.
Network Forensics
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In the event of an attack, this monitoring can play an important part in finding out how the attack was carried out and also by whom.
firewall
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They also keep ports closed and open only those that they expect data to be sent to. For example, incoming emails are usually sent to port 110.
Having ports closed protects the computer from hackers, plus its continual monitoring will help detect hacker activity.
User Access Levels
This is where users of a computer system will be given different access rights depending on their role in the company.
Access levels are important to ensure that employees cannot view sensitive company information (payroll etc) and cannot sabotage vital system data.
Passwords
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As seen before, it is important that passwords are strong so that they are harder to crack under a Brute Force Attack.
encryption
Encryption is where data is scrambled before being sent across a network so that it is unreadable if intercepted.
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