p23 w1 Flashcards
Explain the problem that will occur in storing the normalised floating-point representation of
+65.20 in this system. 2
the decimal fraction 0.20 cannot be represented exactly (the closest
is 0.25 / 0.1875)
MP2 therefore, there will be a loss of precision due to a rounding
error/truncation
Outline the purpose of the Link layer in the TCP/IP protocol suite. 2
MP1 To ensure correct network protocols are followed
MP2 To enable the upper layers to access the physical medium //
enables connection/ communication with the internet / network layer
MP3 To be responsible for transporting data within the network/local
segments
MP4 To format the data into frames for transmission
MP5 Maps IP addresses to MAC/Physical addresses.
Describe what is meant by enumerated and pointer data types.
MP1 A user-defined non-composite (data type) (only award once)
MP2 …with a list of all possible values
MP3 …that is ordered.
One mark per mark point – pointer type (Max 2)
MP4 A user-defined non-composite (data type) (only award once)
MP5 …that stores addresses/memory locations only
Describe sequential and random methods of file organisation.
MP1 Records (in the file) are ordered
MP2 …based on the key field
MP3 A new version (of the file) has to be created to update the file
One mark per mark point – random (Max 2)
MP4 Records are stored in no particular order within the file // There is no
sequencing in the placement of the records
MP5 There is a relationship between the key of the record and its location
within the file // a hashing algorithm is used to find the location of the
record
MP6 Updates to the file can be carried out directly
Outline the process of sequential access for serial and sequential files
MP1 Start at the beginning of the file
MP2 …check records linearly
MP3 …until the desired record is found //
Describe the features of SISD and MIMD computer architectures
One mark per mark point – SISD (Max 2)
MP1 Single Instruction, Single Data (architecture). // Data is taken from a
single source and a single instruction is performed on the data.
MP2 Contains one processor, a control unit and a memory unit.
MP3 …that executes instructions sequentially.
One mark per mark point – MIMD (Max 2)
MP4 Multiple Instruction, Multiple Data (architecture). // At any time, any
processor can execute different instructions on different sets of data.
MP5 Contains many processors
MP6 …that operate asynchronously / independent
State one benefit to the student of a user interface and give an example
One mark for a benefit (Max 1) e.g.
MP1 The user interface hides the complexities of the computer
hardware/operating system from the user
MP2 It provides appropriate access systems for users with differing needs
MP3 Complex commands involving memory locations/buses/computer
hardware/ are avoided
One mark for a valid example (Max 1) e.g.
Clicking on icon rather than writing code
Using a graphical user interface / icons for navigation
Outline conditions under which a process could change from the running state to the ready
state.
MP1 When the time slice of the running process expires (round robin).
MP2 …and there is a process with a higher priority in the ready queue, the
running process is pre-empted
State definition an exception
responding to an unexpected event
when the program is running so it does not halt unexpectedly
State two possible causes of an exception.
Programming errors
* User errors
* Hardware failure
* Runtime errors
Explain how a stack can be used to evaluate RPN expressions. 3
One mark per mark point (Max 3)
MP1 Evaluate the RPN expression from left to right
MP2 Push each element of the RPN expression onto the stack in order
until an operator is reached
MP3 Pop the last two elements from the stack and apply the operator
MP4 Push the result of the operation onto the stack
MP5 Repeat the process until the whole expression is evaluated.
Compare and contrast the queue and stack Abstract Data Types (ADT)
MP1 A queue is a first in first out / FIFO data structure and a stack is a first
in last out / FILO / LIFO data structure // Data is removed from a
queue in the order it is received and removed from a stack in the
reverse order to which it is received
MP2 Both ADTs can vary in size / are of indeterminate length
MP3 Data is popped and pushed (onto/from a stack) at the same end but
it is enqueued and dequeued (to/from a queue) at different/opposite
ends // a queue has two accessible ends and a stack has only one
MP4 A stack has only one moveable pointer whereas a queue has two.
Explain what is meant by the term artificial neural network.
MP1 An artificial neural network is the component of artificial intelligence
that is meant to simulate the functioning of a biological brain.
MP2 Artificial neural networks are a key component of machine learning.
MP3 They can solve problems that would prove impossible or difficult for
humans // Artificial neural networks have self-learning capabilities
that enable them to produce better results as more data becomes
available
MP4 Artificial neural networks can be layered (input, hidden and output
layers) // Artificial neural networks have many interconnected layers,
some / many of which are hidden
MP5 Weights are assigned between nodes
