9608_w16_qp_32
A paper of Computer Science, 9608
Questions:
6
Year:
2016
Paper:
3
Variant:
2
Login to start this paper & get access to powerful tools
1
In a particular computer system, real numbers are stored using floating-point representation with: • 8 bits for the mantissa • 8 bits for the exponent • two’s complement form for both mantissa and exponent Calculate the floating point representation of + 3.5 in this system. Show your working. Mantissa Exponent Calculate the floating-point representation of –3.5 in this system. Show your working. Mantissa Exponent Find the denary value for the following binary floating-point number. Show your working. Mantissa Exponent State whether the floating-point number given in part is normalised or not normalised. Justify your answer given in part . Give the binary two’s complement pattern for the negative number with the largest magnitude. Mantissa Exponent
3. Advanced Theory  →  3.1. Data representation
Open
2
There are four stages in the compilation of a program written in a high-level language. Four statements and four compilation stages are shown below. Draw a line to link each statement to the correct compilation stage. This stage can improve the time taken to execute the statement: x = y + 0 Statement This stage produces object code. This stage makes use of tree data structures. This stage enters symbols in the symbol table. Lexical analysis Compilation stage Syntax analysis Code generation Optimisation Write the Reverse Polish Notation (RPN) for the following expression. P + Q – R / S An interpreter is executing a program. The program uses the variables a, b, c and d. The program contains an expression written in infix form. The interpreter converts the infix expression to RPN. The RPN expression is: b a * c d a + + - The interpreter evaluates this RPN expression using a stack. The current values of the variables are: a = 2 b = 2 c = 1 d = 3 Show the changing contents of the stack as the interpreter evaluates the expression. The first entry on the stack has been done for you. Convert back to its original infix form, the RPN expression: b a * c d a + + - One advantage of using RPN is that the evaluation of an expression does not require rules of precedence. Explain this statement.
3. Advanced Theory  →  3.4. System software
2. Fundamental Problem-solving and Programming Skills  →  2.3. Programming
Open
3
A computer operating system (OS) uses paging for memory management. In paging: • main memory is divided into equal-size blocks, called page frames • each process that is executed is divided into blocks of the same size, called pages • each process has a page table that is used to manage the pages of this process The following table is the incomplete page table for a process, Y. Page Presence flag Page frame address Additional data State two facts about Page 5. Process Y executes the last instruction in Page 5. This instruction is not a branch instruction. Explain the problem that now arises in the continued execution of process Y. Explain how interrupts help to solve the problem that you explained in part . When the next instruction is not present in main memory, the OS must load its page into a page frame. If all page frames are currently in use, the OS overwrites the contents of a page frame with the required page. The page that is to be replaced is determined by a page replacement algorithm. One possible algorithm is to replace the page which has been in memory the shortest amount of time. Give the additional data that would need to be stored in the page table. Complete the table entry below to show what happens when Page 6 is swapped into main memory. Include the data you have identified in part in the final column. Assume that Page 1 is the one to be replaced. In the final column, give an example of the data you have identified in part . Page Presence flag Page frame address Additional data …………. ……… …… …………………….…… Process Y contains instructions that result in the execution of a loop, a very large number of times. All instructions within the loop are in Page 1. The loop contains a call to a procedure whose instructions are all in Page 3. All page frames are currently in use. Page 1 is the page that has been in memory for the shortest time. Explain what happens to Page 1 and Page 3, each time the loop is executed. Name the condition described in part .
3. Advanced Theory  →  3.4. System software
1. Theory Fundamentals  →  1.4. Processor fundamentals
Open
4
Both clients and servers use the Secure Socket Layer (SSL) protocol and its successor, the Transport Layer Security (TLS) protocol. What is a protocol? Name the client application used in this context. Name the server used in this context. Identify two problems that the SSL and TLS protocols can help to overcome. Before any application data is transferred between the client and the server, a handshake process takes place. Part of this process is to agree the security parameters to be used. Describe two of these security parameters. Name two applications of computer systems where it would be appropriate to use the SSL or TLS protocol. These applications should be different from the ones you named in part and part .
3. Advanced Theory  →  3.5. Security
3. Advanced Theory  →  3.2. Communication and Internet technologies
Open
5
A half adder is a logic circuit with the following truth table. Input Output X Y A B The following logic circuit is constructed. X A Y B HALF ADDER X A Y B HALF ADDER P J K Q R Complete the following truth table for this logic circuit. Input Working space Output P Q R J K State the name given to this logic circuit. Name the labels usually given to J and K. Label J Label K Explain why your answers are appropriate labels for these outputs. Write down the Boolean expression corresponding to the following logic circuit: A B C X Use Boolean algebra to simplify the expression given in part . Show your working.
3. Advanced Theory  →  3.3. Hardware
1. Theory Fundamentals  →  1.3. Hardware
Open
6
A Local Area Network (LAN) consists of four computers, one server and a switch. The LAN uses a star topology. Complete the diagram below to show how to connect the devices. Server Computer A Computer B Computer C Computer D Switch The LAN uses packets to transfer data between devices. Three statements are given below. Tick (✓) to show whether each statement is true or false. Statement True False All packets must be routed via the server. Computer B can read a copy of the packet sent from the Server to Computer A. No collisions are possible. In the same building as this star network, there is another star network. Name the device needed to connect the two networks together. Explain how the device in part decides whether to transfer a packet from one network to the other. To avoid the issue of disclosure of answer-related information to candidates, all copyright acknowledgements are reproduced online in the Cambridge International Examinations Copyright Acknowledgements Booklet. This is produced for each series of examinations and is freely available to download at www.cie.org.uk after the live examination series.
3. Advanced Theory  →  3.2. Communication and Internet technologies
Open