Computer Systems Flashcards

(65 cards)

1
Q

What do firewalls do?

A

Check data packets meet requirements ,
Protects against unauthorised access.
Set rules about which stations on a network can send or receive packets

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2
Q

What rules do firewalls take account of?

A

Sender and receiver IP address, port numbers, protocols

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3
Q

What does encryption do?

A

Protects data during transmission
Scrambles data so if stolen can’t understand
Creates simple key that encrypts data
Keeps simple key secure by combination of public and private keys

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4
Q

Public key?

A

Known by everyone, encrypts data

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5
Q

Private key?

A

Known by recipient, decypts data

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6
Q

what is a denial of service(DOS)

A

Floods website or online service so gets overloaded and stop working for real users

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7
Q

4 ways to reduce energy usage

A

Standby mode,hibernate mode,montior settings , power down settings

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8
Q

Standby mode?

A

Ram contunies to be powered, data temoray stored, power to other components reduced or stopped

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9
Q

Hibernate mode?

A

Ram copied to harddisk, hard disk saves perment copy, all compoments off or very low energy use

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10
Q

Monitor Settings?

A

Reduce brightness, activate effeciency mode and don’t use screen saver

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11
Q

Power down settings?

A

Power down after a period of not using(Monitor,desktop/laptop), settings for indivual components

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12
Q

CPU(central processing unit)?

A

fetch, decode, excute instructions from RAM
Preform arithmatic calculations & logical operations
control, read, write,clock, inturrupt and reset lines(all wires)

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13
Q

What parts does the CPU consit of?

A

Control unit, ALU(ARithmatic and logic unit), registers

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14
Q

what does the control unit do?

A

manages the different lines

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15
Q

Clock line?

A

sends out signal to synochrise fetch&excute cycle

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16
Q

Read line?

A

read data from RAM

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17
Q

Write line?

A

writes data to RAM

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18
Q

Reset line

A

clears all registers

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19
Q

Intrrupt lines

A

handle interruptoions to a process during execution

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20
Q

ALU?

A

preforms all calculations, comparisons on numeric vaules, makes decisions based on logic (AND,OR,NOT)

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21
Q

Registers?

A

temorory storage locations in processor, stores addresses,data,instructions, fast access

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22
Q

Types of computer memory

A

different types with different purposes.
Backing storage,main memory, cache,registers

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23
Q

Backing storage?

A

outside proccessor, stores data permently. e.g. usb memory stick

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24
Q

Main memory?

A

Inside computer, types- RAM(Random access memory), ROM (Read only memory)

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25
RAM?
processor reads and writes from RAM, contents lost, holds programs & files when being used, more ram = faster, different locations
26
ROM?
data cannot be changed, contents not lost when turned off, essential data & progams are stored in ROM (e.g. operating system)
27
Cache memory?
fast access, adjacent to processor & main memory, fast access to store data that is needed quickly
28
Register?
storage inside processor, holds data transferred to&from memory, insturctions that are being carried out, addresses of memory locations the processor is accessing.
29
order of different types of memory slowest and biggest to fastest but smallest
Backing storage, RAM, cache, registers
30
Buses?
transfers data from one port to another
31
Data bus?
data transfered to and from main memeroy to processor
32
Address bus?
transfers addresses processor to main memory
33
machine code?
language computer understands, binary
34
Advantages of machine code?
code runs very quickly, does not need to be translated
35
Disadvantgers of machine code?
Difficult for humans to read and understand, only run on the processor type they have been written on
36
High level languages?
created as a machine code is hard, uses english words and phrases
37
Advantages of high level languages
contain english so easeir to read and understand, easier to spot errors, can run on more than one type of processor
38
Disadvantages of high level languages
need to be translated into machine code are slower
39
translators?
translates into machine code so computer can understand
40
types of translators?
Interperter, Compiler
41
Interperter?
Doesn't produce object code (standalone piece), translate one line a time
42
Advantages of Interperters
errors are highlighted immediatly so easier to fix, it will run a partical or devoloping code
43
Disadvangages of interperters
translation not saved, if code is repeated in a loop it runs many times, i ndividual runs slower
44
Compliers?
translates high level language into machine or object code, line at a time saves into a file , don't need to translated again, lists errors , can not be run until all translated
45
Advantages of compilers
If there is no errors does not need to be run again, translator only needed once
46
Disadvantages of comilers
If syntax error won't run, errors may be harder to correct as not idenified till whole code translated
47
GDPR?
General data protection regulation, into force 25th May 2018
48
Implications of GDPR
Data processed fairly,lawfull and transparent manner used for declared purpose only limited to the data needed for declared purpose accurate not held for longer than neccessory held securely
49
what is binary?
a simple two bit system, on/off, used by computers
50
values in binary
128,64,32,16,8,4,2,1
51
floating point reoresation?
represents very big or small numbers in scientic notation
52
what is any number represented in (floating point)
mxb2e m=mantissa b=base e=exponment
53
how to do floating point repersention
point moved in front of first 1 and e(power) must be in binary
54
ASCII?
American standerd code for infornation interchange), was the most popular form of coding a character set
55
what are the two 'types' of Ascii
8 bit extended (256 characters), 7-bit (standard)
56
Whats in a character set
Letters a-z,A-Z, number symbols, punctuation, special characters, control characters
57
what are the first 32 used for in ASCII
Control characters
58
Control characters? Examples?
keys that send instructions without a symbol apperaing (e.g. Deleate key, escape key, tab)
59
Advantages of ASCII
Uses latin characters & alphanumeric, uses less storage than unicode
60
Disadvantages of ASCII
Only makes use of the english language, if unicode is read in ASCII it won't display character correctly
61
two types of graphics
Bitmap and Vector
62
Bitmap
Represented as a grid of pixals , each pixal contains a number of bits to store the colour, more bits more colours, if zoom in to far become pixelated
63
Vector
picture is stored as a collection of mathmatically determined shapes or objects
64
properties of a vector shape
start x&y coordinates, fill colour, line colour, width, height
65
vector shapes?
Rectangle, ellipse, line, polygon