Term
|
Definition
| Path set up between sender and receiver. All data follows the same path, in order. Path can't be used by any other data. |
|
|
Term
|
Definition
| Data splits into packets. Each packet can be transmitted by different routes. Packets can arrive out of order and are re-assembled on arrival. |
|
|
Term
| Advantages of Packet Switching |
|
Definition
+ Better Security as it is very difficult to intercept
+ More efficent of data lines so there are no waiting during gaps
+ Less likely to be affected by network failure because multiple paths are used |
|
|
Term
| 4 Things that a Packet Contains |
|
Definition
- Actual Data
- Source & Destination
- Order Number of Packet
- Error control signals |
|
|
Term
| Why are data structures useful for computing? |
|
Definition
| Convenient way of organising data relating to a real problem |
|
|
Term
|
Definition
| A data structure is a group collection of related data items |
|
|
Term
|
Definition
| It is a tool designed to help students with the management and use of learning materials |
|
|
Term
|
Definition
| It is a world wide networked information and communication system freely accessed via connected computers. |
|
|
Term
|
Definition
| Data collision occurs when two sets of data are detected on the network simultaneously. |
|
|
Term
| What happens when detected (data collisions)? |
|
Definition
| Each computer waits a short amount of time and resends the data |
|
|
Term
| Why is hex sometimes used to replace Binary? |
|
Definition
| It is shortened down so it makes it easier for humans to understand |
|
|
Term
|
Definition
- Allow for completely accurate numbers to be stored
- Requires less complex processing than F.P |
|
|
Term
| Advantages of Floating Point |
|
Definition
- Allows for non integers to be stored. E.g. decimals
- Allows for a much greater range of values to be stored |
|
|
Term
|
Definition
| enables computers to communicate with each other easily because the set is standardised |
|
|
Term
|
Definition
| Records are stored in key sequence order + an index allows data to be accessed directly which is faster. |
|
|
Term
| Define Parallel Transmission |
|
Definition
| Occurs when a number of bits are sent simultaneously. |
|
|
Term
| Define Serial Transmission |
|
Definition
| Occurs when bits are sent one by one along the data channel. |
|
|
Term
| Define Simplex, Half Duplex and Full Duplex |
|
Definition
Simplex - data can only be sent in one direction
Half Duplex - data can be sent in both direction but only one at a time
Full Duplex - Data can be sent in both directions at the same time. |
|
|
Term
|
Definition
| Where several independent data sources are combined to be sent along a single route to a single destination. |
|
|
Term
| What is a Switch and why is it needed? |
|
Definition
A Switch connects segments of a network together.
It prevents data from being sent to all parts of the network |
|
|
Term
|
Definition
| A device which holds the addresses of the computers on a network and can direct data to the correct computer |
|
|
Term
|
Definition
| A set of rules which specifies how data is transmitted across a network. |
|
|
Term
|
Definition
| Involves the collection of programs/data for processing together. |
|
|
Term
|
Definition
| The amount of time allocated to each job by the OS |
|
|
Term
|
Definition
| The method by which the processor time is allocated (in a MTOS). |
|
|
Term
|
Definition
| The division of computer memory for different jobs. |
|
|
Term
|
Definition
| The process of waiting to be executed by the processor because another process is currently being run |
|
|
Term
|
Definition
| The process that is waiting for some event usually an I/O operation |
|
|
Term
|
Definition
| Using an area of memory to store data when transferring data to/from a slower device peripheral. |
|
|
Term
|
Definition
| Whilst one buffer is being emptied another can be filled. Faster than single. |
|
|
Term
|
Definition
| Number is approximated to the nearest hundredth, tenth etc |
|
|
Term
|
Definition
| Number is approximated to the lower hundredth/tenth(near zero) |
|
|
Term
|
Definition
| A set of data elements of the same data type, accessed via an index |
|
|
Term
|
Definition
| A set of data items all related to a single entity. |
|
|
Term
|
Definition
| A linked list is a list of data elements where each elements contains the data itself and a pointer to the next element. |
|
|
Term
|
Definition
| Occurs when the number is too large to be stored satisfactorily by the comkputer |
|
|
Term
|
Definition
| Occurs when the number is too close to 0 zero to be stored satisfactorily by the computer |
|
|
Term
|
Definition
| Records are stored in key field order |
|
|
Term
|
Definition
| A main index contains the address & locations of the next level indexes, this may extend several levels. The last level indexes contain the physical addresses of the records. |
|
|
Term
|
Definition
| The storing of data not currently in use but is kept for historical/security reasons and stored securely off-site |
|
|
Term
| Define a Flat File Database |
|
Definition
| May contain a number of single tables with no links between them. |
|
|
Term
|
Definition
| A primary key is a field which uniquely identifies a record in a database. |
|
|
Term
|
Definition
| A foreign key is a primary key from one table included in another table to form a link. |
|
|
Term
| What is an Index used for? |
|
Definition
| It is used to improve access times to records |
|
|
Term
|
Definition
| The data items are dependent on the key, the whole key and nothing but the key. |
|
|
Term
|
Definition
| This is when you store the data more than once |
|
|
Term
|
Definition
| Due to data only being stored once, all instances of the data will be updated if a change in made |
|
|
Term
|
Definition
| Data in a database should be able to be used with any other database applications |
|
|
Term
|
Definition
| Where large quantities of data are collected together from a variety of locations for efficient analysis |
|
|
Term
|
Definition
| The analysis of large amounts of data (in a data warehouse) to provide new information or find patterns. |
|
|
Term
|
Definition
| The person in a company who is responsible for the structure and management of the database system and the data in it. |
|
|
Term
|
Definition
| Used when a user wants to search data in a DB |
|
|
Term
|
Definition
| A sequence of steps designed to solve a specific task. |
|
|
Term
|
Definition
| A set of program instructions performing a specific task, but which is not a complete program. |
|
|
Term
|
Definition
| An algorithm which calls itself. It must also have a terminating condition. |
|
|
Term
|
Definition
| A subroutine that performs a task but does not return a value. |
|
|
Term
|
Definition
| A subroutine that performs a task and returns a value. |
|
|
Term
|
Definition
| A value than can be passed to/from a procedure. |
|
|
Term
|
Definition
| A local copy of the data is created for the procedure (discarded later). |
|
|
Term
|
Definition
| The address of the data is passed to the procedure (rather than the actual value of the data). |
|
|
Term
|
Definition
Items copied 1 by 1 from input array to output array
Each new item is inserted in correct place in the output array |
|
|
Term
|
Definition
Start at beginning – Compare elements 1 and 2
If element 1 > 2, swap values, then compare 2 and 3
Repeat until sort requires no more swaps |
|
|
Term
|
Definition
Splits list of values into 2 sub-lists, based on pivot value (≤ and >)
This is repeated again on the 2 SL’s, and again on those new SL’s
This is until each SL only contains one value (Uses Recursion) |
|
|
Term
|
Definition
| Carries out a standard task for a standard situation in a program. |
|
|
Term
|
Definition
| Contain pre-coded common modules which avoid rewriting. |
|
|
Term
|
Definition
| Concerned with carrying out actions or calculations. |
|
|
Term
|
Definition
| To do with facts, rules and making queries. |
|
|
Term
|
Definition
| The precise way program statements must be written to be understood by the computer. |
|
|
Term
|
Definition
| Used to describe (unambiguously) the syntax of a programming language. |
|
|
Term
|
Definition
| A computer program used to convert a program from one language to another. |
|
|
Term
|
Definition
| A software tool that translates a program (or module) written in a high-level language, into machine code, ready for execution. |
|
|
Term
|
Definition
| A software tool that executes programs by reading each statement and immediately performing the action. |
|
|
Term
|
Definition
| A software tool which allows already compiled files to be combined with a compiled program and made into an exe. |
|
|
Term
|
Definition
| A program which that copies a compiled program from backing store into main memory, for execution. |
|
|
Term
|
Definition
| Converts programs in assembly code to machine code. |
|
|
Term
|
Definition
| A software tool used to assist and speed-up the creation of a system. |
|
|
Term
|
Definition
| Occurs when the program is being compiled (usually syntax errors). |
|
|
Term
|
Definition
| Errors which are detected during program execution |
|
|
Term
|
Definition
| The simultaneous use of several processors to perform a single task. |
|
|
Term
|
Definition
| The use of computer technology for commercial operations such as sales from B2B or B2C. |
|
|
Term
|
Definition
| A web log is a set of entries on the world wide web (which is accessible to other web users). |
|
|
Term
|
Definition
| A system where a human life is at risk if the software fails. |
|
|
Term
|
Definition
| A computer controlled device which can carry out complex tasks and utilities sensors, microprocessors and actuatos |
|
|
Term
|
Definition
| An application accessed over the Internet, which can be used to search for web sites on a particular topic. |
|
|
Term
| Advantages and Disadvantages of Serial Transmission |
|
Definition
+ Can be used for large distances
+ Requires only 2 wires
- Slower than parallel transmission |
|
|
Term
| Advantages and Disadvantages of Parallel Transmission |
|
Definition
+ Faster than serial transmission
- Requires 8/16 wires
- Can on be used for short distances due to interference |
|
|
Term
| What is the protocol for collision detection called? |
|
Definition
| CSMA/CD (Carrier Sense Multiple Access/Collision Detection) |
|
|
Term
|
Definition
Multi-programming is when more than one job is held in the computer’s main memory and each job can be processed by the CPU at the same time.
1. This is to ensure the most efficient use of the CPU and prevents the CPU from being idle whilst waiting for a slower peripheral/device
2. Real-time clocks cause regular interrupts to create time slices
3. The OS moves jobs in & out of main memory and allocates each job a pre-determined time slice to access the CPU, this process is called scheduling (controlled by a scheduler program)
4. Each job is checked sequentially to ensure that they get an appropriate share of time, this process is called polling
5. To allow more than one job to reside in main memory at any one time, the memory needs to be separated into different parts, this process is called partitioning |
|
|
Term
| Interrupt Priority Routine |
|
Definition
The OS suspends the current routine
Runs the new higher priority routine
Returns to the original interrupt routine once finished |
|
|
Term
|
Definition
The Interrupt register sets up levels via flag bits and depend on.
Importance of the requesting device/software
Length of time required to service the interrupt |
|
|
Term
|
Definition
Run-time error
I/O request
User request
Software failure |
|
|
Term
|
Definition
Peripheral/device
Timer pulse
Power failure
Hardware failure |
|
|
Term
| What is a Queue? and what the uses? |
|
Definition
First in first out
Print Jobs, Characters Typed, |
|
|
Term
| Advantages of Linked Lists |
|
Definition
+ Easy to program
+ Elements are stored in order
+ New elements can be inserted without rearranging the other elements |
|
|
Term
| Disadvantages of Linked Lists |
|
Definition
-Fixed array size
-More complex to program than an array
-Can only be accessed in a linear manner |
|
|
Term
|
Definition
- Items can be searched easily & quickly
- Items can be added easily
- The whole tree can be printed in sequence |
|
|
Term
|
Definition
The physical location of a new record is calculated using a hashing algorithm from the key field
If the location is empty, the data is stored there, if not the data is stored in an overflow area |
|
|
Term
| How data is stored in an overflow area? |
|
Definition
Data in the overflow area is usually stored and searched in a linear manner.
When access of a record in required the process is the same hashing algorithm used to derive the location.
If the overflow area becomes too big, access time may increase and the file might need to be reorganized whereby a new hashing algorithm is used |
|
|
Term
| How to add a record to a sequential file |
|
Definition
Create a new file and start copying over the existing records
Add the new records in place during this procedure
Continue copying over the remaining existing records until the end of the file |
|
|
Term
| How to delete a record to a sequential file |
|
Definition
Create a new file and start copying over the existing records
Skip the records that are to be deleted
Continue copying over the remaining existing records until the end of the file |
|
|
Term
|
Definition
Physical Security
secuirty guards, locks on rooms
Files Backups
: make a backup of all important files; a three generation backup system involves storage of the three of the most recent versions of a master file. If one version becomes corrupted the previous versions are still available
Transaction Logs
an online system can use a transaction log to keep a record of all the transactions that have taken place. If the database becomes corrupt, the latest backup of the database can be updated using the transaction log
Archiving
Passwords
can only be accessed by authorised users using a username/ID and password. The operating system can set certain access to certain files, e.g. no access
Encryption
can be used to safeguard data being transferred between computers or when storing files |
|
|
Term
| Scripting Language Features |
|
Definition
High level language
Interpreted, not compiled
Embedded within other languages
Adds functionality to web pages |
|
|
Term
|
Definition
High level language
Uses objects/classes (include both data and associated processing)
Produces buttons & icons (very useful in GUI) |
|
|
Term
|
Definition
Useful for database query
Uses report generators
May have a natural language interface (no rigid grammatical rules
Requires less programming skill |
|
|
Term
|
Definition
Only contains the relevant features
Used for simulation, control etc.
More expensive
Not readily available |
|
|
Term
|
Definition
Can be used for developing a GUI
Event driven language
Very difficult to use in a text based environment |
|
|
Term
| Package with Programming Facilities |
|
Definition
is probably cheaper / quicker since most facilities are provided by the package
• can import / export from / to other packages
• is less likely to contain errors “bugs” / package has already been well tested
• more help is available in the package
• users are probably familiar with interface |
|
|
Term
| Advantages of Standardisation |
|
Definition
A program written in one language/platform is likely to run on others
A programmer familiar with one language is likely to be able learn it quicker |
|
|
Term
|
Definition
The input stream is broken into tokens
Comments & whitespace are removed
Error messages are generated if appropriate
A symbol table is produced for the variables |
|
|
Term
|
Definition
The tokens are checked to see if they comply with the syntax of the language, using BNF-style rules
Error messages are generated if appropriate |
|
|
Term
|
Definition
A check is made to see if all the variable have been declared
Type checks ensure that no mixed mode arithmetic occurs (i.e. real values assigned to integers) |
|
|
Term
|
Definition
Machine code is generated
Code optimisation may occur to reduce the execution time of the program |
|
|
Term
|
Definition
| Lexical Analysis, Syntax Analysis, Semantic Analysis, Code Generation |
|
|
Term
|
Definition
Object code can be saved and rerun without compilation
Executes faster than interpreted code
Can be distributed without an interpreter
More secure (against reverse engineering |
|
|
Term
| Interpretation Advantages |
|
Definition
- Complete recompilation not necessary when an error is found
- Easier to perform partial testing and debugging
- Can be used during program development |
|
|
Term
| What is Design Validation? |
|
Definition
It is to check to ensure a design meets the objectives and user requirements.
it confirms that the HCI is appropriate |
|
|
Term
| What is Evaluation Criteria? |
|
Definition
• A set criteria to review the design of a system, this includes:
Easy to use? Reliable? |
|
|
Term
What is a natural language interface?
Give the Advantage and Disadvantage. |
|
Definition
The user can talk naturally to the computer to give instructions normally
+ The computer can communicate back
- Very complex, high processing power needed |
|
|
Term
|
Definition
A GUI is an interface where most communication is via screen elements e.g. windows, icons, menus, pointers
A GUI system is easier to learn/ more intuitive to use
No need to remember complex commands
Usually good help facility included |
|
|
Term
| Speech Recognition Interface |
|
Definition
Commands and/or text input are given to the computer via human speech
Can be used by someone doing another task with their hands/unable to use hands
Can have difficulty with proper nouns/homophones |
|
|
Term
|
Definition
• Input to the computer is typed via text
Can allow complex/unusual commands not available with a GUI
May run more quickly/ user fewer resources than a GUI
Takes a novice a long time to learn |
|
|
Term
|
Definition
Computer prompts for input into specific fields on a screen dialogue form
Cursor may move automatically to next input field
May include validation – only some entries allowed |
|
|
Term
|
Definition
+ Quicker and easier for user than typing
+ Avoids Bulky keyboards
- May not be very accurate
- Limited access for disabled people
- PC needs to learn users style |
|
|
Term
|
Definition
• Useful for things like telephone banking
• Useful for people with visual impairment
• Can be annoying/obtrusive
• Can involve heavy hardware performance |
|
|
Term
| E-commerce Impact on High Streets |
|
Definition
+ Provides support and collection of online sales
- Less physical customer base |
|
|
Term
| E-commerce Impact on Employment |
|
Definition
+ More opportunity for web development
- Less shop staff |
|
|
Term
| E-commerce Impact on Health |
|
Definition
+ Beneficial for physically disabled customers
- Less Exercise walking to shops |
|
|
Term
| E-commerce Impact on Enviroment |
|
Definition
+ Reduced private transport
- Increase in logistical transport |
|
|
Term
|
Definition
• Touch – detecting pressure
• Sight – video image analysis
• Sound – speech recognition
• Smell – chemical analysis
• Taste – biosensor detection
• Heat – infrared scanners |
|
|
Term
| Advantages of Robot Systems |
|
Definition
Can perform tasks quicker and more efficiently than humans
Can be used 24/7; unaffected by fatigue or illness
Cheaper in the long term
Can work in hazardous environments (extreme temperatures, toxic fumes, radiation etc.) |
|
|
Term
| Disadvantages of Robot Systems |
|
Definition
Remaining staff need to be highly skilled to be of any use
Robots may not notice obvious errors when working
Robots may not notice dangers (e.g. fires)
Expensive to purchase/manufacture/maintain/repair |
|
|
Term
|
Definition
| These are software systems with large databases that include a built in set of facts and rules which enable them to appear to have expertise in certain areas |
|
|
Term
| Advantages of Expert Systems |
|
Definition
Saves time for human experts as they are not the ones dealing with the analysis
They can assess simpler things while human experts deals with bigger problems
They do not ‘forget’ information
Data can be kept up to date 24/7
They can be used at a distance over a network |
|
|
Term
| Disadvantages of Expert Systems |
|
Definition
- They cause a loss in jobs
- There is less human contact when using expert systems
- They may cause legal/ethical issues
-More expert systems lead to deskilling of certain professions |
|
|
Term
| Biometric Security Process |
|
Definition
A person’s retina/fingerprint/voice is originally captured, digitised and stored
On attempted entry, the person’s given identification is captured and digitised
The digitised images are compared, a successful match will result in a successful entry |
|
|
Term
| Why is Disaster recovery needed? |
|
Definition
• Many organisations could not survive if their system failed as data is vital to organisations
• All computer systems are liable to fail eventually
• Computer systems can’t always be protected, e.g. natural disasters |
|
|
Term
| What should be included in a disaster plan? |
|
Definition
1. Regular backups of the system
2. Archiving files safely off site
3. An alternative system should be on standby
4. A backup power supply
5. The possibility to rebuilt lost damaged data |
|
|
