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
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...
Function: to temporarily store data, note that registers are not part of main memory.
Purpose: to carry data within the motherboard. There are three buses within the CPU...
: transmits the location of the data to be read/written.
: transmits the operation being performed.
: transmits the actual data to be read/written.
Arithmetic and Logic Unit
Function: process and manipulate data, consists of arithmetic and logical operations.
Description: cache memory is very small but fast memory. It stores regularly used data and instructions so the CPU can access it quicker.
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.
It has limited capacity.
It is very expensive.
Function: to carry out the fetch-decode-execute cycle.
Describe different types of memory and caching
The typical contents of RAM are
data and programs
which means any data on it is
power is lost
stored on the RAM is
The effect of adding more RAM on a computer system
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 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.
which means it
keeps its contents
even when there is
The typical contents of
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 (
before being transferred.
Describe and explain 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
by all available processors.
Any task can be processed by an processor.
Tasks can be shared
between processors to
and avoid bottlenecks.
can be processed in a
from different processors need to be
This can be complex and takes time to pass data between subtasks.
Not all tasks can be split
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
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.
The instruction is executed.
Each stage is designed to run concurrently to maximise resources.
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.
- holds the code read from the currently addressed memory location.
- holds the most recently fetched machine code instruction.
- holds the address of the currently addressed memory location.
- holds data which is part of calculations.
- points to the next instruction to be fetched and executed.
Describe the use of contemporary methods and their associated devices for input and output
Compare the functional characteristics of contemporary secondary storage devices
Follow the link for a table of comparisons:
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
back into the empty space.
Files then get
physically stored elsewhere
on the disk. Consequently, it
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
to collect all the
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.
of data through
using IP addresses.
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.
Requires lots of cable which is expensive.
If the hub goes down or is switched off, the whole network fails.
Response time deteriorates with many users.
If the main cable breaks then it may be the point of failure.
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.
(Hyper Text Transfer Protocol) - transfer of multimedia web pages. Importance: allows different web browsers to display and format web pages as originally intended.
(File Transfer Protocol) - transfer of large files over a network. Importance: in-built error checking and re-transmission request.
(Dynamic Host Configuration Protocol) - assigns IP addresses to devices on a network. Importance: ensures dynamic IPs are allocated automatically.
(Simple Mail Transfer Protocol) - sending emails over a network. Importance: standard way of transferring emails between two servers.
(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.
(Transmission Control Protocol/Internet Protocol) - communication between any networked computers. Importance: creates data packets and specifies how they are routed and transported.
(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
The Client accesses network services and the server provides the network services (file, mail and web server).
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.
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)