Please enable JavaScript.
Coggle requires JavaScript to display documents.
Hardware and Communication (Describe networks and how they communicate…
Hardware and Communication
Identify and describe the hardware and communication elements of contemporary computer systems and how they are connected
Hardware:
describes all the physical, electronic and mechanical components forming part of a computer system.
Identify and describe the main components of contemporary computer architecture, including Von Neumann architectures.
The five main components of contemporary computer architecture are...
Registers
Function: to temporarily store data, note that registers are not part of main memory.
Buses
Purpose: to carry data within the motherboard. There are three buses within the CPU...
Address
: transmits the location of the data to be read/written.
Control
: transmits the operation being performed.
Data
: transmits the actual data to be read/written.
Arithmetic and Logic Unit
Function: process and manipulate data, consists of arithmetic and logical operations.
Cache memory
Description: cache memory is very small but fast memory. It stores regularly used data and instructions so the CPU can access it quicker.
Advantages
CPU can access it more quickly that it can RAM.
It ensures fast access to instructions.
PCs with slower processors but larger caches tend to faster than those with the opposite.
Disadvantages
It has limited capacity.
It is very expensive.
Control Unit
Function: to carry out the fetch-decode-execute cycle.
Describe different types of memory and caching
RAM (
R
andom
A
ccess
M
emory)
The typical contents of RAM are
data and programs
that are
currently
in use.
RAM is
volatile
which means any data on it is
temporary
. Once
power is lost
,
all data
stored on the RAM is
lost
.
The effect of adding more RAM on a computer system
Generally speaking
,
adding more RAM
to a computer system will
speed it up
as it means
more applications can be open at once or a particularly memory-intensive application can be run
smoothly. Also, it
eliminates the need for virtual memory
as there is enough physical memory.
However, if there is
already a sufficient amount
of RAM in a computer system to run the applications being used, then upgrading RAM will
not affect the speed or performance
of a computer system
ROM (
R
ead
O
nly
M
emory)
ROM is used to
store the start-up instructions
for a computer, known as firmware.
Any data on ROM is
permanently etched onto the chip
and cannot be removed.
ROM is
non-volatile
which means it
keeps its contents
even when there is
no power.
The typical contents of
ROM
are the
firmware
and the
bootstrap loader.
Disc cache
Disc cache is located between the CPU and disc
. It is where
data recently read
from the disc or is
about to be written
to the disc is (
temporarily
)
stored
before being transferred.
Describe and explain parallel processing
Parallel processing:
two or more processors working together to perform a single task (concurrently).
It is where a
large task is split into smaller sub-tasks
. These tasks are
executed simultaneously
by all available processors.
Any task can be processed by an processor.
Advantages
Tasks can be shared
between processors to
reduce workload
and avoid bottlenecks.
More instructions
can be processed in a
shorter time.
Disadvantages
Results
from different processors need to be
combined
.
This can be complex and takes time to pass data between subtasks.
Not all tasks can be split
between processors.
More difficult to write programs f
or multi-core systems.
Concurrency introduces new classes of software bugs.
For example, race conditions. One task could require data from another sub-task but that sub-task isn't complete.
Describe the fetch-execute cycle showing how data can be read from RAM into registers
Decode
The instruction in the MDR is copied to the CIR (Current Instruction Register).
The instruction held in the CIR is decoded by the Control Unit.
Execute
The instruction is executed.
Each stage is designed to run concurrently to maximise resources.
Fetch
Instruction is fetched from that address in RAM and is copied to the MDR.
The PC is incremented.
Address of the next instruction is copied from the PC to MAR.
Key words
MDR
- holds the code read from the currently addressed memory location.
CIR
- holds the most recently fetched machine code instruction.
MAR
- holds the address of the currently addressed memory location.
Accumulator
- holds data which is part of calculations.
Program Counter
- points to the next instruction to be fetched and executed.
Describe the use of contemporary methods and their associated devices for input and output
Input
Microphone
Graphics Digitiser
Mouse
Optical scanners
Keyboard
Sensor
Output
Inkjet Printer
Laser Printer
Speakers
Plotter
Monitor
Compare the functional characteristics of contemporary secondary storage devices
Follow the link for a table of comparisons:
https://drive.google.com/file/d/1NqJbCmhhDEiTvvDal4TzL304xc1yzMUz/view?usp=sharing
Explain fragmentation and its consequences and describe the need for defragmentation
As normal, the
file system will fill
up over time as you create more and more files. Then, any
changes you make
to files may
result in blocks
no longer touching as they
won't fit
back into the empty space.
Files then get
split up
and are
physically stored elsewhere
on the disk. Consequently, it
takes longer
for the
disc heads
to move between parts of the file which
slows the loading process.
Defragmentation gathers all the data
on a disk by
moving all parts of files
into an empty area. Also, defragmentation
moves files
to collect all the
free space
together in order to
prevent further fragmentation.
Describe networks and how they communicate
A network is a linked set of computer systems, which may be capable of sharing computer power and resources such as printers and databases.
Networks
communicate
by
sending packets
of data through
switches
using IP addresses.
Star Topology
Advantages
Easier to detect faults.
The network will still continue with a cable break.
Easier to add new stations.
Data has to pass through the hub/switch, making it more secure.
Disadvantages
Requires lots of cable which is expensive.
If the hub goes down or is switched off, the whole network fails.
Bus Topology
Disadvantages
Response time deteriorates with many users.
If the main cable breaks then it may be the point of failure.
Ring Topology
Disadvantages
If the ring is broken then the network will fail.
It is difficult to add new stations.
Describe the importance and the use of a range of contemporary protocols including HTTP, FTP, SMTP, TCP/IP, IMAP, DHCP, UDP and wireless communication protocols.
Application Protocols
HTTP
(Hyper Text Transfer Protocol) - transfer of multimedia web pages. Importance: allows different web browsers to display and format web pages as originally intended.
FTP
(File Transfer Protocol) - transfer of large files over a network. Importance: in-built error checking and re-transmission request.
DHCP
(Dynamic Host Configuration Protocol) - assigns IP addresses to devices on a network. Importance: ensures dynamic IPs are allocated automatically.
SMTP
(Simple Mail Transfer Protocol) - sending emails over a network. Importance: standard way of transferring emails between two servers.
IMAP
(Internet Message Access Protocol) - downloading emails from a mail server. Importance: same as SMTP plus messages are stored on the server instead of devices, this saves space.
Transport Protocols
TCP/IP
(Transmission Control Protocol/Internet Protocol) - communication between any networked computers. Importance: creates data packets and specifies how they are routed and transported.
UDP
(User Datagram Protocol) - sends datagrams across a network with very few error recovery services. Importance: e.g. video and audio streaming protocols are designed to handle occasional lost packets and need to receive new packets rather than the re-transmission of previous ones.
Explain the importance of networking standards
Client-Server
The Client accesses network services and the server provides the network services (file, mail and web server).
Protocols
A protocol is an agreed set of rules that allow two devices to communicate.
They can be for wired or wireless transfer.
Why are networking standards important?
Easy to develop one 'layer' at a time.
It's impossible to create networks that can communicate without standards.
Allows communication between different networks.
Allows multiple companies to work together towards standardisation.
More competitive pricing.
Explain the role of handshaking
Handshaking is the process by which two devices establish their readiness to communicate.
Process...
Device 1 will send a signal to Device 2
Device 2 will acknowledge the signal
Device 1 sends another signal of acknowledgement
Device 1 begins the transmission.
Describe the internet in terms of a world-wide communications infrastructure
The internet is a world-wide communications infrastructure. It is 'a network of networks'.
Concurrently means at the same time (simultaneously)