Blog stuff I need to do

Python


Programming




  

Networking

Computers are connected with networks.                           






Server: Software that provides services to a client, or the hardware that is running it.


Client: Software or hardware that requests services from a server.








Advantages




They allow data to be shared very easily. Everyday activities such as bookings, ordering things and making phone calls would be much slower without networks. In many organisations, colleagues have to work together and the ability to share data is vital to that so networks are also very important to the workplace.




Disadvantages




Building and keeping a network running needs a lot of experts so it can be expensive for some companies. A team of analysts and technicians are vital for a good network.


Networks can be accessed by unauthorised people which may want to steal data so strong passwords are needed which must also must be changed often. Some websites and software should be blocked because viruses can be downloaded which will enter networks and steal information.

Software

Software is a collection of programs that tell the computer what to do. They are used by programmers or people using the computer to do what they want with the computer. They are used to perform tasks.


Writing a program needs the use of programming languages. 

Testing

Error occur because commands haven't not been entered or use correctly. Everything is flawed.

Syntax errors are errors that are to do with how code is entered such as typos.

Logical errors are errors where the syntax is correct but the logic in the problem is wrong, such as a  program where dividing by 0 occurs.


Test data.
Valid= test data that represents typical input into the valid system.
Valid extreme= test data that is valid but at the extreme end of the range of acceptable.
Invalid= Test data that is out of range and should be rejected.
Invalid extreme= test data that is invalid but only just at the limit of being unacceptable
Erroneous= test data that should be rejected because it is the wrong type of input.
                  

                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   




































































                                                                                                 
                                                  

Databases

A database is a persistent organised store of similar data on a computer system. Persistent means it is stored in secondary storage which means it can be accessed later.


There are different models for database.









Key terms
Serial file: A file of items one after another

Sequential File: A serial file in order

Entity: Something that we store data about in a database

Record: All the data about one item in a database

Attribute: A characteristic of an entity. It becomes a field in a data table.

Field: A characteristic of something stored in a database

Indexed sequential file: A sequential file that is accessed using an index which is separate file.

Flat file database: Database consisting of only one table





A database can be used to hold information in a business e.g. employees salary, employee background. 


Key field:

Little Man Computer

The little man computer uses instructions

Instruction	Mnemonic	Machine Code
Load	LDA	5xx
Store	STA	3xx
Add	ADD	1xx
Subtract	SUB	2xx
Input	INP	901
Output	OUT	902
End	HLT	000
Branch if zero	BRZ	7xx
Branch if zero or positive	BRP	8xx
Branch always	BRA	6xx
Data storage	DAT

The memory locations on the side of the simulator change numbers. It is one of the first computer programs, it was made in 1965 by Dr Stuart Madnick.  It is very basic program as it can only input and output numbers and some other commands.

revision

Binary codes can represent characters when converted into ascii
Hexadecimal numbers are used to represent binary numbers because binary numbers get very large and difficult to calculate.

00000011=3=3
binary   denary    hex




Character set- the characters available on the computer