9608_w18_qp_33
A paper of Computer Science, 9608
Questions:
6
Year:
2018
Paper:
3
Variant:
3
Login to start this paper & get access to powerful tools
1
Consider the following user‑defined data type. TYPE Book DECLARE ISBN : INTEGER DECLARE Author : STRING DECLARE Title : STRING DECLARE Supplier : (Amazone, Stones, Smiths, Blackwalls, Greens, Coals, Boarders) ENDTYPE Name the data type of Book. Name the non‑composite data type used in the Supplier declaration. Write a pseudocode statement to declare a variable, BestSeller, of type Book. Write a pseudocode statement to assign “John Williams” to the author of BestSeller.
3. Advanced Theory  →  3.1. Data representation
Open
2
A computer system stores real numbers using floating‑point representation. The floating‑point numbers have: • eight bits for the mantissa • four bits for the exponent. The mantissa and exponent are both in two’s complement form. Calculate the denary value of the following floating‑point number. Mantissa Exponent Show your working. Working Answer State how you know the floating‑point number in part is not normalised. Normalise the floating‑point number in part . Mantissa Exponent Write the largest positive number that this system can represent as a normalised floating‑point number in this format. Mantissa Exponent Write the smallest positive number that can be stored as a normalised floating‑point number in this format. Mantissa Exponent The number of bits available to represent a real number is increased to 16. State the effect this has on the numbers that can be represented, if the additional four bits are used in the: mantissa exponent A student enters the following code into an interpreter. X = 0.1 Y = 0.2 Z = 0.3 OUTPUT (X + Y + Z) The student is surprised to see the output: 0.6000000000000001 Explain why this is output.
3. Advanced Theory  →  3.1. Data representation
Open
3
A local college has CSMA/CD in operation on its Local Area Network (LAN). One function of CSMA/CD is to monitor traffic on the network. State two other tasks performed by CSMA/CD. The network uses the TCP/IP protocol to transfer files across the network. State three functions of the TCP part of this protocol. State two functions of the IP part of this protocol. Identify one other common protocol that could be used to transfer files across the college network. Protocols are essential for successful transmission of data over a network. The TCP/IP protocol suite operates on many layers. Give an appropriate protocol for each layer in the table. Layer Protocol Application Transport Internet The TCP/IP protocol is used to send an email message from one node on a LAN to a node on a different LAN. State the steps that take place when the email message is sent and received.
3. Advanced Theory  →  3.2. Communication and Internet technologies
Open
4
A Boolean expression corresponds to the following truth table. INPUT OUTPUT A B C X Write the Boolean expression for the truth table by applying the sum‑of‑products. X = Complete the Karnaugh Map (K‑map) for the truth table. AB C The K‑map can be used to simplify the expression in part . Draw looparound appropriate groups of 1s in the table in part to produce an optimal sum‑of‑products. Write the simplified sum‑of‑products expression for your answer to part . X = A logic circuit with four inputs produces the following truth table. INPUT OUTPUT A B C D X Complete the K‑map that corresponds to the truth table. AB CD Draw looparound appropriate groups of 1s in the table in part to produce an optimal sum‑of‑products. Write the simplified sum‑of‑products expression for your answer to part . X =
3. Advanced Theory  →  3.3. Hardware
1. Theory Fundamentals  →  1.3. Hardware
Open
5
A computer process can be in one of three states: running, ready or blocked. Explain how the processes are affected when the following events take place. The running process needs to read a file from a disk. The running process uses up its time slice. State the conditions that are necessary for a process to move from the ready to the running state. State the conditions that are necessary for a process to move from the blocked to the ready state. Give three reasons why process scheduling is needed.
3. Advanced Theory  →  3.4. System software
1. Theory Fundamentals  →  1.4. Processor fundamentals
Open
6
The compilation process has a number of stages. The first stage is lexical analysis. A compiler uses a keyword table and a symbol table. Part of the keyword table is shown. • Tokens for keywords are shown in hexadecimal. • All of the keyword tokens are in the range 00 – 5F. Keyword Token * = IF 4A THEN 4B ENDIF 4C ELSE 4D FOR 4E STEP 4F TO INPUT OUTPUT ENDFOR Entries in the symbol table are allocated tokens. These values start from 60 . Study the following code. Start INPUT Number // Output values in a loop FOR Counter Start TO 12 OUTPUT Number * Counter ENDFOR Complete the symbol table to show its contents after the lexical analysis stage. Symbol Token Value Type Start Variable Constant The output from the lexical analysis stage is stored in the following table. Each cell stores one byte of the output. Complete the output from the lexical analysis stage. Use the keyword table and your answer to part . The output of the lexical analysis stage is the input to the syntax analysis stage. Identify two tasks in syntax analysis. The final stage of compilation is optimisation. Code optimisation produces code that minimises the amount of memory used. Give one additional reason why code optimisation is performed. A student uses the compiler to compile some different code. After the syntax analysis stage is complete, the compiler generates object code. The following lines of code are compiled. X A + B Y A + B + C Z A + B + C + D The compilation produces the following assembly language code. LDD 236 // loads value A to accumulator ADD 237 // adds value B to accumulator STO 512 // stores accumulator in X LDD 236 // loads value A to accumulator ADD 237 // adds value B to accumulator ADD 238 // adds value C to accumulator STO 513 // stores accumulator in Y LDD 236 // loads value A to accumulator ADD 237 // adds value B to accumulator ADD 238 // adds value C to accumulator ADD 239 // adds value D to accumulator STO 514 // stores accumulator in Z Rewrite the assembly language code after it has been optimised.
3. Advanced Theory  →  3.4. System software
1. Theory Fundamentals  →  1.4. Processor fundamentals
2. Fundamental Problem-solving and Programming Skills  →  2.3. Programming
Open