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Summary Matric IEB Information Technologies (IT) : Summaries
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This is a complete summary of the Information Technologies (IT) matric theory IEB syllabus. Summaries made from "Exploring IT Grade 12 Theory"
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Actually passed IT with a distinction using my notes, it’s on you if you lack the basic knowledge not covered in them
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Unit 11.1 Modular Design
-Computers are built with modular design.
-Which means - can be put together in pieces with you own requirements.
-Hardware not fixed.
-Smaller technologies are less modular. i.e phones
-Hardware parts are separate, connected via the motherboard using ports and
slots.
-Simplifies computer upgrading
1.2 Factors influencing the performance of a computer
1.2.1 CPU
1.2.1.1 CPU speed
-Does not achieve optimum performance in isolation.
-register and bus size, hyper threading and multiprocessing, cache and RAM,
all have a part to play.
1.2.1.2 Overclocking
-Can be achieved:
● per component, CPU operates faster than system clock by changing
clock multiplication factor
● The whole system, system clock increased affecting all components
that detect system clock and multiply by a factor.
-Clock multiplication, increase speed but can be dangerous causing computer
to be unstable to fail.
-Air and liquid cooling can help reduce overheat risk.
1.2.1.3 Register size
-32 bit processes data in 32 groups and 64 bit process data in 64 groups,
does not influence speed.
-but a 32 bit processes 64 bit numbers in two stages and 64 bit only in one
stage, does affect the speed.
1.2.1.4 Hyperthreading
,-Developed by intel
-processor appears to execute two threads at the same time.
-achieved by having two sets of registers on the CPU.
-each time processor switch between two processors then the state or value
in all registers relating to a process must be saved to slower RAM and the
state of the next processors must be loaded from RAM to registers.
-Must be supported by operating system.
1.2.1.5 Multiprocessing
-multiple CPU on single CPU chip
-processors run at the same time.
-must be supported by the motherboard
1.2.2 Registers and Data buses
-Main advantage between 32 bit register and 32 bit address bus, is 2^32
memory addresses (4GB RAM) can be addressed while 64 bit address bus can
address 2^64 addresses (17.2 billion GB RAM).
-Larger the data bus the more data can be transferred to CPU at one time.
1.2.3 Primary Memory: Cache and RAM
-Different types of RAM can have big impact on performance
-data moved in and out of RAM
-amount of cache influences performance, because of higher speed
-SRAM located close/in the CPU
-Processor checks if instruction has already been previously executed, in
cache
-larger cache = more instructions stored.
-More RAM = less virtual memory = faster
1.2.4 Access to and from secondary storage
Dependant on:
- Speed of technology
- Latency of drive
-Popular bus/drive combination is the SATA.
-Popular secondary storage:
- USB flash drives (minimal and fast)
- SSD
, 1.2.5 Solid State Speed vs Mechanical Drive Speed
-Mechanical drives, limited by the fact that they having moving parts
-Access time = seek time + latency
-SSD, time much less, no moving parts
-SSD do not need to be defragmented
1.2.6 Peripheral Interfaces
-Speed and type of peripheral can affect performance, may require an
interface.
-Interface allows computer to communicate with peripheral.
-buffer may exist between data transit
-Factors that influence communication with CPU and peripheral:
● Data conversation - changing data into form CPU understands
● Protocol conversation - changing types e.g serial to parallel
● Voltage conversion - may have to perform at different voltages
1.3 Networking issues
1.3.1 Network speed
1.3.1.1 The external network speed
-Upload and download speeds provided by broadband service coming into local
network.
-Contention speed - the offered speed could be high, but is divided by
number of users using network.
-Contention ratio - maximum number of people to share connection with
(50:1)
1.3.1.2 The internal network speed
-Number of network switches has to connect through to access network
resources, can cause bottlenecking.
-ensure all switches in network are of same speed to prevent bottleneck
10/100/1000.
-More users = more data = performance deteriorates
-Ethernet is shared media, no rules for sending packets, avoiding conflict
and protecting data integrity.
-Minimize collisions to reduce performance drops is important
-Segmenting - network is divided into pieces and logically joined together
using, bridges, switches, routers, reduces congestion
, -Factors affecting network efficiency:
● Amount of traffic
● Number of nodes
● Size of packets
● Network Diameter
1.3.1.3 NIC Speed
-Ethernet network cards typically support 10 Mbit/s, 100 Mbit/s, 1000
Mbit/s Ethernet. 10/100/1000.
-Transfer rates are reduced by traffic demands on NIC (e.g background
backups)
1.3.1.4 Cabling
-UTP network cabling is usually category 5 cable (Cat 5), Cat 5e
(enhanced), Cat 6 or Cat 6a.
-Fibre optic best performance, expensive, used at a backbone.
1.3.1.5 Wired vs Wireless
● Wired
-superior performance
-more reliable
-better control and security
-offer 10/100/1000
● Wireless
-wifi
-distance sensitive
-wireless devices utilise the WLAN more heavily = greater performance
degrades.
-environment where multiple WAPs are used with same SSID, cross-talk
between WAPS can occur and dead spots can be encountered.
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