OCR A-level Computer Science Paper 1 Unofficial Mark Scheme

Watch
Devestation
Badges: 6
Rep:
?
#1
Report Thread starter 1 year ago
#1
So I've been searching through the computer science section of the forum trying to find discussions as to how individuals found the exam so I can feel better about myself but all I could find was very vague comments and some prediction comments from 4 or more weeks ago. Thus I have decided to make a mark scheme to encourage discussion among the papers. I'll get the mark scheme started off; please post any questions that you may remember down below and I will do my best to add them.

Q1) When P is false and S is true then that means that the robot is listening. Fill in the truth table. (4 MARKS)

I can't quite remember the exact question and what was given but what you needed to do for this was to:
Put 'True' in the listening section where P was false and S was true. The other 3 missing values within the truth table are 'False'.

Update:
======================
TRUTH TABLE
======================
True True 0
True False 0
False True 1
False False 0
======================

Q2) Draw a logic circuit to represent the truth table. (4 MARKS)

This question required an NOT gate from the P value followed by an AND gate linking the two inputs to the output L.

Q) Fill in the table for the LMC program above.
======================
INPUT OUTPUT
======================
1 1
2 4
3 9
======================

Q5) Write the run-length encoded version of the string. (2 MARKS)

I can't remember the exact string so i will use a similar example with the following concept that should have been applied.
AABBCMMAAAA
would become
2A2B1C2M4A

Q8 ii) What is meant by the term Lexical analysis? (2 MARKS)
Breaks down the input source code into a sequence of lexemes. It reads the input source code character by character, recognizes the lexemes and outputs a sequence of tokens describing the lexemes.

Q) What is meant by Atomic in terms of a transaction (2 MARKS)

Atomicity is when half finished data can't be saved so in a transaction the data has to be fully completed in order for the transaction to go through.

Q) Fill in the stages of compilation. (3 MARKS)

Consistency
Isolation
Durability

Q) Discuss the positive and negative impacts computers have on the Environment (9 MARKS)

Advantages:
Raise awareness for charities and how much damage is being done reducing environmental damage as people more aware.
Communication systems online such as Skype or Facebook allow for individuals to talk to one another therefore there is no need for people to travel to meet one another reducing pollution as less fuel is being burnt and released into the environment.
Computers allow for emailing which reduces the need for printing therefore less paper is being used.

Disadvantages:
Computers produce technological waste which can be harmful to the environment.
Raw materials are being used to supply energy to data centers impacting the environment negatively as more raw materials are extracted.
Last edited by Devestation; 1 year ago
1
reply
H3LL0_W0RLD
Badges: 10
Rep:
?
#2
Report 1 year ago
#2
I can't remember question numbers exactly but the question about ACID Transactions was Atomicity, Concistency, Isolation, Durability.

For the 9 marker about "Discuss the positive and negative impacts computers have on the Environment" I talked about how they raised awareness for charities and how much damage was being done, I also talked about the amount of energy required to run data centres, and the amount of raw materials used to make plastic and circuit as well as the planned obsolescence of phones and small computers which leads to an increase is waste

The truth table for the first question looked like this
P S L
True True 0
True False 0
False True 1
False False 0

For the question about the hash table, to manipulate the string you had to use the locate() function they gave you, as well as the string.substr() they give you in the Psuedocode guide in the specification. Bit of a tricky one if you haven't looked at the guide at the back but it is very useful, especially for the second paper.

To get a substring:
stringname.subString(startingPos ition, numberOfCharacters)
NB The string will start with the 0th character.

Example

someText="Computer Science"
print(someText.length)
print(someText.substring(3,3))


Will display
16
put

The LMC question was a Squaring Machine/ it multiplies the input by itself. Which meant the table looked like
1 1
2 4
3 9

Question 8 was the basic program, I can't remember exactly the order but one of them was a Integer and the other one was a String. Also it talked about Lexical Analysis in the later part of the question and asked what happens. Which is it breaks down the input source code into a sequence of lexemes. It reads the input source code character by character, recognizes the lexemes and outputs a sequence of tokens describing the lexemes.

The other 9 marker was about What technologies should a web developer know to work for a web design company

As part of the hashing question you were asked how you would solve the hash table collisions, for example OCR and RND had the same hash.

The 12 marker asked to compare Linked Lists to Hash Tables in terms of their suitability for a Firewall whitelist. The firewall would be accessed 7 times a second and they needed to be able to add 10 new websites a day to the list.

The run time encoding question was asking you to group the letters together like CCC meant 3C, then you had to write a function longest that would return the longest run of the character C which meant the longest run of cars.
0
reply
Devestation
Badges: 6
Rep:
?
#3
Report Thread starter 1 year ago
#3
(Original post by H3LL0_W0RLD)
I can't remember question numbers exactly but the question about ACID Transactions was Atomicity, Concistency, Isolation, Durability.

For the 9 marker about "Discuss the positive and negative impacts computers have on the Environment" I talked about how they raised awareness for charities and how much damage was being done, I also talked about the amount of energy required to run data centres, and the amount of raw materials used to make plastic and circuit as well as the planned obsolescence of phones and small computers which leads to an increase is waste

The truth table for the first question looked like this
P S L
True True 0
True False 0
False True 1
False False 0

For the question about the hash table, to manipulate the string you had to use the locate() function they gave you, as well as the string.substr() they give you in the Psuedocode guide in the specification. Bit of a tricky one if you haven't looked at the guide at the back but it is very useful, especially for the second paper.

To get a substring:
stringname.subString(startingPos ition, numberOfCharacters)
NB The string will start with the 0th character.

Example

someText="Computer Science"
print(someText.length)
print(someText.substring(3,3))


Will display
16
put

The LMC question was a Squaring Machine/ it multiplies the input by itself. Which meant the table looked like
1 1
2 4
3 9

Question 8 was the basic program, I can't remember exactly the order but one of them was a Integer and the other one was a String. Also it talked about Lexical Analysis in the later part of the question and asked what happens. Which is it breaks down the input source code into a sequence of lexemes. It reads the input source code character by character, recognizes the lexemes and outputs a sequence of tokens describing the lexemes.

The other 9 marker was about What technologies should a web developer know to work for a web design company

As part of the hashing question you were asked how you would solve the hash table collisions, for example OCR and RND had the same hash.

The 12 marker asked to compare Linked Lists to Hash Tables in terms of their suitability for a Firewall whitelist. The firewall would be accessed 7 times a second and they needed to be able to add 10 new websites a day to the list.

The run time encoding question was asking you to group the letters together like CCC meant 3C, then you had to write a function longest that would return the longest run of the character C which meant the longest run of cars.
Thanks for your response. The following have been added.
0
reply
Ariyaa
Badges: 11
Rep:
?
#4
Report 1 year ago
#4
Now we need the paper 2 mark scheme, or at least a discussion on how people found it. How did you guys find it? The merge sort caught me out 😪
2
reply
CompSciNinjaCat
Badges: 4
Rep:
?
#5
Report 1 year ago
#5
Hi, please could you do a paper 2 mark scheme from the 11th? Or if there is one that already exists, point me in the direction of that? Thanks
1
reply
username3191094
Badges: 6
Rep:
?
#6
Report 1 year ago
#6
I thought it was mainly okay. The 9 markers were somewhat vague but nothing too out of the norm for computer science
(Original post by Ariyaa)
Now we need the paper 2 mark scheme, or at least a discussion on how people found it. How did you guys find it? The merge sort caught me out 😪
0
reply
KB0708
Badges: 1
Rep:
?
#7
Report 10 months ago
#7
INP STA numloop LDA total ADD num STA total LDA count ADD one STA count SUB num BRZ end BRA loopend LDA total OUT HLTone DAT 1num DAT 0count DAT 0total DAT 0The above is the LMC code from the June 2019 paper. I dont see how it is a Squaring Machine multiplying the input by itself.
0
reply
ezcash
Badges: 1
Rep:
?
#8
Report 8 months ago
#8
what were some of the questions that anyone could remember?
0
reply
X

Quick Reply

Attached files
Write a reply...
Reply
new posts
Back
to top
Latest
My Feed

See more of what you like on
The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

Personalise

What do you want most from university virtual open days and online events?

I want to be able to watch in my own time rather than turn up live (189)
29.3%
I want to hear more about the specifics of the course (106)
16.43%
I want to be able to dip in and dip out of lots of different sessions (58)
8.99%
I want to meet current students (54)
8.37%
I want to meet academics and the people that will be teaching me (51)
7.91%
I want to have a taster lecture or workshop to see what the teaching is like (128)
19.84%
My parents/guardians are more interested than me to be honest (38)
5.89%
Other things – I'll tell you in the thread (21)
3.26%

Watched Threads

View All