3.2.1 Fundamentals of Computer Systems key words

Hardware is the physical electronic components of the computer e.g. the mother board and graphics card.

Software is the programs and data that run upon the hardware, there are several types of software:

High level software:

System software-software that performs the tasks needed to operate the hardware, again this software can be broken down into 4 other sub sectors these are operating system(performs the tasks that are needed to drive the hardware and acts as an interface for the hardware); library programs(These are programs that  other programs use to get to other things like to access the internet or use printers) ;utility programs(Programs that normally run in the background and usually helps to analyse, optimise and configure your computer like antivirus ) and finally translator programs.

The three translator programs are: an assembler is used to translate assembly code(slightly easier to work with that machine code but still difficult)  into machine code.

A compiler translate the whole source code and maximises it until object code is produced which can then be run, it's fairly slow but only has to be done once and it needs no other program to run it.

A interpreter analyses high level programming like VB and instead of going through a compiler it follows the program out line by line. This is means that the program runs slowly but can be run straight away but has to be done every time you want to use it unlike a compiler ,its often used for simple adverts on the web.

Application Software-is software that allows the user to do generic tasks like writing a letter or listening to music(this is what most people think of as software) but it can be separated into 3 categories.

General purpose-used for many tasks and fairly diverse examples are word processors and spreadsheets usually bought off the shelf they give the user the same thing to everyone else.

Special purpose-does one task very well but can't do much else like route planning software or internet browsers.

Bespoke applications-this is software that is taylor made for a company and the customer get exactly what they want a good example is air traffic control software, can be made by payed for contractors or in-house programmers. Very expensive.

Generations of programing language:

1st gen- machien code the only code the computer can really understand in binary

2nd gen- assembly code

3rd gen-imperative high level as in VB and Java

4th gen- declarative this is were you basicaly tell what the computer what you want to do and it pretty much works it out

Key words and notes for revision 1

The internet is the whole network of networks that’s sends information along thousands of different global paths to other computers.

The web is a small part of the internet that is comprise of webpages, multimedia, text and things that use HTML as structure and transportation.

The intranet is a miniature internet that is private to a network. That can only be accessed internally like the school network.

The extranet is a part of the intranet that has been published to the public like the schools Jogport.

A router is a specialise computer that knows enough about its local part of the internet to send packets generally to the right direction to get to the wanted location. There are many of these to redirect info at each junction of the internet.

Packets are small amounts of data that were part of a larger data e.g.  a document  that has been downloaded. They are broken down into three parts:  The header-this contains the sender’s and receiver’s ip address and the packet sequence; the payload that contains the broken down information and finally the trailer that checks for errors during the send and receive process. 

The domain name is for the use of people to be an easily remembered instead of the ip address. Composed of a top level domain followed by sub domains (first level, second level etc….) working from right to left.

The ip address   is the computers version of a domain name that is binary; they are 8 bite binary number. Every computer has a unique ip address to stop packets from going to the wrong computer.

Domain name server translates the human domain name to the computers ip addresses to locate .They are scattered all over the internet and are constantly updated.

Isp or internet service provider are people like sky that provide you with an internet connection.

Internet registries are people that check for availability of ip addresses and hand them out.

Internet registrars’ are the people who monitor domain name and the people who you buy the rights to a domain name.

URI stands for uniform resource identifier and is the general term for unique identification

URL stands for uniform resource location and uses the specific location in the website address bar for instance

The client is a computer on a network that is sending the request for the resources off the internet from another computer e.g  your computer asking a website to download a file.

The server is the computer on the network that the client is asking for the resources, it is made up from many small computers to make towers.

TCP/IP is code for Transition Control Protocol over the Internet Protocol and are responsible for together moving info around the internet.TCP breaks down the information and turns it into packets of data and transmits it. The IP is responsible for finding other computers and rerouting it around the internet. The TCP/IP can be broken down into 4 layer and is call the TCP/IP protocol stack. The 4 layer are:

The application layer- this is the specific networking application e.g a web browser.

The Transport Layer - this layer breaks the data into small packets and in the header adds the source and destination ports and the packet sequence

The network layer- this layer adds the source and destination IP address to the headers in the packets

The link layer-this layer adds the MAC address to the packet and puts the data on the cable to the nearest router on the network

Here are some common protocols and their port numbers. (sourced for Mr.Klines' Powerpoint)