Edexcel GCSE Computer science key questions And
UPDATED ANSWERS
Process for communication in the client-server network model.
1. The client uses the address of the server to make a connection.
2. The client sends a request to the server.
3. The server obtains the address from the client once the client makes a connection to
the server.
4. The server sends the requested data to the client.
Benefits of using subprograms when writing software solutions
1. Are written only once.
2. Therefore, can be called from anywhere in the program.
3. Needs to be debugged only once.
4. Makes the main program shorter.
> More readable.
5. Reduces the need for global variables.
6. Can be used to hide complex coding.
7. Can be reused in other programs.
,Why should constants be used in programs?
1. Readability
> Makes it understandable for the readers.
> Not everyone will know the relevance and
understand what the literal values mean.
2. Ability to update
> If the value of the constant needs updating, it only has
to be done once instead changing all of the occurrence
of the value.
3. Compiler optimisation
> Depending on the compiler, use of named constants can lead to optimisation.
> Either by improving performance or by reducing memory space.
Fetch-decode-execute cycle
FETCH
:Copy PC onto address bus and read from RAM
:RAM content comes back on data bus to IR
:Increase PC by 1
DECODE
:CU examines instructions and fetches required data
:CU puts the address of the required data on the address bus - RAM
:RAM puts contents of that address on that data bus
:Put data in R0
EXECUTE
:Copy R0 into ACC
Encryption
1. Encryption such as provided by the VPN
, 2. Ensures that private or sensitive data which is sent over the Internet
3. Cannot be understood by unauthorised users ( such as hackers ).
> Data is unintelligible to third parties.
4. Reduces the risk of companies losing important data
> E.g. private customer details or company secrets
> Could have financial or legal impacts.
Steps to improve security of important data
Using encryption
___________________
1. Encryption such as provided by the VPN
2. Ensures that private or sensitive data which is sent over the Internet
3. Cannot be understood by unauthorised users ( such as hackers ).
> Data is unintelligible to third parties.
4. Reduces the risk of companies losing important data
> E.g. private customer details or company secrets
> Could have financial or legal impacts.
Creating passwords
_____________________
1. Logon passwords.
2. Passwords should be required to log into the computer and access data.
UPDATED ANSWERS
Process for communication in the client-server network model.
1. The client uses the address of the server to make a connection.
2. The client sends a request to the server.
3. The server obtains the address from the client once the client makes a connection to
the server.
4. The server sends the requested data to the client.
Benefits of using subprograms when writing software solutions
1. Are written only once.
2. Therefore, can be called from anywhere in the program.
3. Needs to be debugged only once.
4. Makes the main program shorter.
> More readable.
5. Reduces the need for global variables.
6. Can be used to hide complex coding.
7. Can be reused in other programs.
,Why should constants be used in programs?
1. Readability
> Makes it understandable for the readers.
> Not everyone will know the relevance and
understand what the literal values mean.
2. Ability to update
> If the value of the constant needs updating, it only has
to be done once instead changing all of the occurrence
of the value.
3. Compiler optimisation
> Depending on the compiler, use of named constants can lead to optimisation.
> Either by improving performance or by reducing memory space.
Fetch-decode-execute cycle
FETCH
:Copy PC onto address bus and read from RAM
:RAM content comes back on data bus to IR
:Increase PC by 1
DECODE
:CU examines instructions and fetches required data
:CU puts the address of the required data on the address bus - RAM
:RAM puts contents of that address on that data bus
:Put data in R0
EXECUTE
:Copy R0 into ACC
Encryption
1. Encryption such as provided by the VPN
, 2. Ensures that private or sensitive data which is sent over the Internet
3. Cannot be understood by unauthorised users ( such as hackers ).
> Data is unintelligible to third parties.
4. Reduces the risk of companies losing important data
> E.g. private customer details or company secrets
> Could have financial or legal impacts.
Steps to improve security of important data
Using encryption
___________________
1. Encryption such as provided by the VPN
2. Ensures that private or sensitive data which is sent over the Internet
3. Cannot be understood by unauthorised users ( such as hackers ).
> Data is unintelligible to third parties.
4. Reduces the risk of companies losing important data
> E.g. private customer details or company secrets
> Could have financial or legal impacts.
Creating passwords
_____________________
1. Logon passwords.
2. Passwords should be required to log into the computer and access data.
