A signal can contain one or more bits;
Bit rate can be higher than baud rate;
bit rate = baud rate * number of bits per signal change;;
-
Procedures and functions are often self-contained. What is meant by the term
- self-contained in this context?
Do not use any global variables// use only local variables and/or
parameters;
- Give one reason why the use of global variables may introduce program bugs.
Local and global variables with the same name can be misidentified//
difficult to test individual procedures/ functions//
Not clear that as a side-effect of executing procedure/function a global
variable could change its value;
- Describe one example of the use of a stack
Reverse the contents of a queue/list;
Push all contents of queue/list onto stack then pop them off into a new
queue/list;
Procedure/function calls;
Local variables;
Parameters;
Return Address;
- Describe one example of the use of a Binary Search Tree.
list of elements inserted into tree;
to allow rapid/fast searching of the data;
to output sorted/ordered data;
- What is meant by each of the following?
- Internet
world-wide collection of networks/computers using TCP/IP
collection of servers using Hypertext Transfer Protocol/HTTP//
computers connected within a small geographical area/building/site;
computers connected over a large geographical area;
Network providing Internet facilities within an organisation/
LAN using Internet protocol; (1 mark)
(b) Give an example of:
any valid domain name, e.g. aqa.ac.uk; R www.aqa.ac.uk
any valid address in the range 0.0.0.0 to 255.255.255.255
- Explain what is meant by a library program
program files which are used by other/many applications
- Explain one difference between a procedure and a function
functions always return some value when called;
procedures may return a value
- Name and describe a built-in function you have used in your programming work,
or when using a generic software package.
anything named which is plausible;
examples could include: computation / formatting / string handling
- Name two other uses for identifiers in a high level language
program / constant / function / procedure / module / unit / user defined type / record / label /
object / class ;
- The programming language being used has both compiler and interpreter software for program development.
Give one advantage of the use of each.
Interpreter advantage should allow faster/easier program development // faster/easier testing / debugging / finding
errors ;
correcting mistakes is less time consuming
Compiler advantage the executable code/object code/program will run faster ;
once the executable file has been produced no further action ;
software distribution requires no further software to be available to the user ;
prevents tampering of the code by users other than the developer ;
electrical/electronic/physical components/parts of computer/system
- Define the term information
Processed data / data with structure / organised data / data which have been sorted / data given a
context (and therefore meaningful to the recipient) //
Any form of communication which gives understandable/useful knowledge to the person
receiving it
- What is meant by serial data communication?
Bits are sent along a single wire/line // bits are sent one after the other / .bit by bit
- Explain what is meant by the stored program concept.
program consists of a sequence of instructions;
program/instructions stored in main memory;
and can be replaced by another program at any time;
instructions are fetched ;
instructions are decoded ;
Instructions are executed
- What is dial-up networking?
only connected when in use/when Internet required/non-permanent
connection / need to re-connect to go on line
- Explain the function of a modem
translates digital signal into analogue / analogue signal into digital;
computer uses digital signals / telephone line transmits analogue signals
- Explain the term protocol.
set of rules (about the way devices communicate)
- Explain the term handshaking.
sending signals between devices + implication of 2-way ;
confirmation of ready for sending / receiving data;
acknowledge that a transfer is completed;
- Explain what is meant by synthesised sound.
Sound which has been produced using the computer/from software ;
Sound which has been digitally produced ;
- Give an example where synthesised sound would be produced and used
Any plausible example where sound is not naturally produced
e.g. keyboard synthesiser /computer generated voice response / mobile
- Define the term software.
computer programs/sequence of instructions which run on the hardware/perform some
task
- Explain the difference between hardware and software
Hardware is the electronic / electrical / electronic circuits / /physical
components/ parts of computer
- Use this example to explain the terms:
- Data
- Numbers recruited to each course / the target number of students
(b) Information
Bytes/numbers/values which make up the BMP file / spreadsheet file
Universal Serial Bus;
an internal web site/set of web pages // web site local to an
organisation ;
(web) pages which can only be viewed with authority/provided with
access from the organisation ;
- Describe what is meant by a local area network.
computers/devices/nodes/PCs connected/linked/communicate together ;
-
State the principle of operation of a set of data values which behave as a stack.
Last (item) in, is the first (item) out / first (item) in is the last (item) out ; 1
- Explain why the data bus is bi-directional, but the address bus is one-way only.
data bus has to transport data values to and from various devices/internal components ;
Only the processor assigns address values to the different devices
- Explain the stored program concept.
program instructions are transferred from backing store to main memory ;
program consists of a sequence of instructions ;
program is stored in main memory ;
and can be replaced by another program at any time ;
instructions are fetched (in sequence) ;
decoded ;
and then executed
- Describe how interpreter software enables a program written in a high level language
to be executed.
The interpreter software is resident in memory at the same time as the
application program is run ;
The interpreter recognises/translates/reads/converts each statement A.
instruction/line;
- A friend gives you a copy of a freeware assembler. Why might you not be able to use
this successfully on your computer?
The processor/architecture/(hardware) platform is different ;
instructions are not the same ;
Assembler software is processor/architecture specific ;
- Define asynchronous data transmission.
Data is transmitted intermittently (rather than as a steady stream) ;
Sender and receiver are only synchronized when data is being sent // start bit
synchronises the receiver