2023 m/j 32 Flashcards
describe the reason why the normalized form of the following binary number cannot be represented accurately using this system
the mantissa of the number would need to be 0.101011111001 / 13
bits / digits
it can only store 10 bits / digits
The 3 least significant digits would be truncated
causing a loss of precision
describe how records are organized and accessed in a sequential file
–records are stored in a particular order
– the order is determined based on the value in a key field
– records are accessed one after the other
–records can be found by searching from the beginning of the file,
record by record,
– until the required record is found or key field value is exceeded.
define encapsulation
the process of putting data and methods together as a single unit
define getters
methods used to return the value of a property
define polymorphism
allows methods to be redefined for derived classes
define setters
methods used to update the value of property
describe the purpose of quantum cryptography
— to produce a virtually unbreakable encryption system / send
virtually un-hackable secure messages …
— using the laws / principles of quantum mechanics / properties of
photons
— detects eavesdropping …
— because the properties of photons change
— to protect security of data transmitted over fibre optic cables
— to enable the use of longer keys.
explain the difference between symmetric and asymmetric cryptography when encrypting and decrypting data
— Symmetric cryptography uses a single key to encrypt and decrypt
messages, Asymmetric cryptography uses two.
— The symmetric key is shared, whereas with asymmetric, only the
public key is shared (and the private key isn’t).
— the risk of compromise is higher with symmetric encryption and
asymmetric encryption is more secure.
— Symmetric cryptography is a simple process that can be carried out
quickly, but asymmetric is much more complex, so slower.
— The length of the keys in symmetric encryption are (usually) shorter
than those for asymmetric (128/256 bits v 2048 bits).
the format of data type
TYPE TAppointments
DECLARE Name : STRING
DECLARE DateOfBirth : DATE
DECLARE Telephone : STRING
DECLARE LastAppointment : DATE
DECLARE NextAppointment : DATE
DECLARE TreatmentsComplete : BOOLEAN
ENDTYPE
pseudocode algorithm reads dental records stored in a random file using the user-defined data type ‘TAppointments’ and prints the contents of the file, one record at a time.
DECLARE DentalRecord : ARRAY[1:250] OF TAppointments
DECLARE DentalFile : STRING
DECLARE Count : INTEGER
DentalFile=>”DentalFile.dat”
OUTPUT “The file “, DentalFile, “ contains these records:”
OPENFILE DentalFile FOR RANDOM
Count => 1
REPEAT
SEEK DentalFile, Count
GETRECORD DentalFile, DentalRecord[Count]
OUTPUT DentalRecord[Count]
Count => Count + 1
UNTIL EOF(DentalFile)
CLOSEFILE DentalFile
state two examples of where it would be appropriate to use packet switching
— Packet switching is most commonly used on data networks such as
the internet to send large data files that don’t need to be live streamed
— Packet switching is used when it is necessary to be able to overcome
failed/faulty lines by rerouting.
— Packet switching is used when it is necessary for the communication
to be more secure.
— Packet switching is used for high volume data transmission.
— Packet switching is used when it isn’t necessary to use all the
bandwidth.
— Specific examples e.g. email, text messages, documents, VOIP etc
give four differences between circuit switching and packet switching
— Circuit switching uses a dedicated channel to make communication,
whereas packet switching forms data into packets to transmit over a
digital network.
— The dedicated path for circuit switching must be established before
the transfer of data can commence, which is not the case with packet
switching (as it doesn’t require a dedicated path).
— Data in packet switching is split into packets, in circuit switching the
message remains intact.
— All of the transmission in circuit switching follows the same path
whereas different packets in packet switching can take different
routes.
— The message is received in the same order in which it is sent with
circuit switching, but with packet switching, the packets can be
received out of order (for assembly at the destination).
— Circuit switching is implemented at the physical layer while packet
switching is implemented at the network layer.
— Circuit switching uses the whole bandwidth of the channel used,
packet switching can share bandwidth.
— Circuit switching communication ends with an error but packet
switching allows packets to be re-sent.
— Circuit switching is a simpler process than packet switching.
describe the use of pipelining in reduced instruction set computers(RISC)
— Pipelining allows several instructions to be processed simultaneously
/ concurrently.
— therefore, increasing the CPU instruction throughput / the number
of instructions completed per unit of time.
— Each instruction stage / subtask is completed during one clock cycle
— No two instructions can execute their same stage of instruction /
subtask at the same clock cycle.
— e.g., while one instruction is being decoded, the next instruction
can be fetched, etc.
stats one category of machine learning
— Supervised (learning)
— Unsupervised (learning)
— Reinforcement (learning)
— Deep (learning)
queue abstract data type(ADT)
CONSTANT MaxLength = 50
DECLARE FrontPointer : INTEGER
DECLARE RearPointer : INTEGER
DECLARE Length : INTEGER
DECLARE Queue : ARRAY[0:MaxLength – 1] OF STRING
// Initialisation of queue
PROCEDURE Initialise
FrontPointer <= -1
RearPointer <= -1
Length <= 0
ENDPROCEDURE
// Adding a new item to the queue
PROCEDURE Enqueue(NewItem : STRING)
IF Length < MaxLength THEN // IF Length <= MaxLength -
1 THEN
RearPointer <= RearPointer + 1
IF RearPointer > MaxLength – 1 THEN
RearPointer <= 0
ENDIF
Queue[RearPointer] <=NewItem
Length Length + 1
ENDIF
ENDPROCEDURE
