A Level Computer Science 9618 Paper 31, May/June 2024

conversion of exponent 001001 to 9

application of exponent to mantissa to go from 0.100111100 to 100111100 // 256 + 32 + 16 + 8 + 4 seen // 64/128 + 8/128 + 4/128 + 2/128 + 1/128 = 79/128 // 1/2 + 1/16 + 1/32 + 1/64 + 1/128 = 79/128

correct answer = 316

number converted to binary 10011001.01 // number converted to positive 102.75, reversed bits and 1 added. (0)1100110.11 ⇨ 10011001.00 ⇨ 10011001.01 // -128 + 16 + 8 + 1 + 0.25 = –102.75

exponent = 7 // Moving binary point the correct number of places

correct answer (Mantissa: 1 0 0 1 1 0 0 1 0 1, Exponent: 0 0 0 1 1 1)

All protocols in correct position (Application, Transport, Internet, Link)

The transport layer is responsible for delivery of data from the source host to the destination host

It is where data is broken up into packets and sent to the internet layer

Name of protocol

Expansion/description of protocol

Non-composite data types can both be user-defined or primitive / do not refer to other data types in their definition / contain one data type in their definition / can be primitive/enumerated/pointer

Second point for non-composite data types or composite data types

Composite data types can be user-defined or primitive / refer to other data types in their definition/contain more than one data type in their definition / can be record/set/class

TYPE FootballClub and ENDTYPE correct

First two correct declarations

Second two correct declarations

Third two correct declarations

Sequential access method searches for records one after the other

… from the physical start of the file until the record is found/the end of file.

For serial files, records are stored in chronological order

… every record needs to be checked until the record is found, or all records have been checked.

For sequential files, records are stored in order of a key field/index, and it is the key field/index that is compared / … every record is checked until the record is found, or the key field of the current record is greater than the key field of the target record.

(5 + 2)

/ (9 – 3)

* 3

7 3 +

2 8 * - 6 /

First ring (stacks 1 to 3: [17], [17, 5], [12])

Second ring (stacks 4 to 6: [12, 7], [12, 7, 3], [12, 10])

Third ring (stack 7: [120])

Fourth ring (stacks 8 to 9: [120, 10], [12])

working, all four columns P, Q, R and S

first four rows of column Z

second four rows of column Z

all five correct terms and no extras ((Z =) Ā.B̄.C̄ + Ā.B̄.C + A.B̄.C + A.B.C̄ + A.B.C)

All cells in Karnaugh map correct

Loop for entire row A=1

Loop for 2x2 group (A=0,1 with BC=00,01)

A + B̄

A digital certificate is an electronic/online document.

used to authenticate/prove the identity of a website/the online identity of an individual/organisation

typically issued by a CA // For example: it contains information identifying a website owner/individual and a public key

The digital certificate provides the public key

… that can be used to validate the private key associated with the organisation/website/digital signature

(23) feature(sliding_doors).

(24) available(sliding_doors, minivan).

(25) unavailable(sliding_doors, hatchback).

(Options =) sunroof, reversing_camera

feature(F)

bodystyle(B)

unavailable(F, B)

all correct Boolean operators and punctuation (allow , for AND) and no additional lines of code

Deep learning learns by finding hidden patterns that are undetectable to humans.

It structures algorithms in layers: input layer, hidden layers and output layer / … to create an artificial neural network to learn and make intelligent decisions on its own.

It is trained using large quantities of unlabelled data / Deep learning requires/uses a large number of hidden layers / … the larger the number of layers, the higher the level of success.

The elements are sorted according to the compare function / in ascending / descending order.

Correctly initialising TopOfList, EndOfList, Found, NotInList and getting input

WHILE loop condition and calculation of CurrentItem DIV 2

IF ToFind = Names[CurrentItem] check and setting Found to TRUE

Checking TopOfList >= EndOfList and updating TopOfList / EndOfList correctly

Correct conditional output based on Found

Big O for a binary search is O(Log₂ n) // Big O notation is used to indicate the time/space complexity of an algorithm.

The time taken to complete the search increases logarithmically as the number of search items increases linearly // The time taken to complete the search increases linearly as the number of search items increases exponentially // As the search field is repeatedly getting smaller, the number of comparisons made before the item is found, or the number of items runs out, is relatively small.

Uses hard-wired code/control units / Uses relatively few instructions / simple instructions / Uses relatively few addressing modes / Makes use of a single-cycle for each instruction

Makes use of fixed length / fixed format instructions / Makes use of general-purpose registers / Pipelining is straightforward to apply / The design emphasis is on the software / Processor chips require few transistors.

Once the processor detects an interrupt at the start/end of the fetch-execute cycle

… the current program is temporarily stopped and the status of each register stored on the stack.

After the interrupt has been serviced/the Interrupt Service Routine (ISR) has been executed … // … the registers can be restored to its original status before the interrupt was detected // … the data can be restored from the stack.

Pipelining adds an additional complexity // there could be a number of instructions still in the pipeline when the interrupt is received

All the instructions currently in operation are usually discarded except for the last one/the one at write back // … the interrupt handler routine is applied to the remaining instruction.

Once the interrupt has been serviced the processor can restart with the next instruction in the sequence.