Paper 2 (written)

Represent −45 as an 8-bit two's complement binary number.

Convert 11010011 to hexadecimal.

A floating-point number has an 8-bit two's complement mantissa 0.1010000 and a 4-bit two's complement exponent 0011. Calculate its denary value.

Explain why floating-point numbers are normalised.

A 3-minute stereo recording is sampled at 44.1 kHz with 16-bit resolution. Calculate the file size in megabytes (1 MB = 10⁶ bytes).

Calculate the size in bytes of an uncompressed 1920 × 1080 bitmap with a colour depth of 24 bits.

Explain how run-length encoding works and why it is effective for some images but not others.

Explain the difference between lossy and lossless compression.

Explain why the Vernam cipher is said to offer perfect security.

Simplify A·B + A·B̄ + Ā·B, showing your working.

Use De Morgan's laws to write NOT(A + B) and NOT(A · B) in another form, and state one use of logic simplification.

Explain the difference between system software and application software, with an example of each.

Compare compilers and interpreters.

Describe the fetch stage of the fetch–decode–execute cycle, referring to the registers used.

Explain how clock speed, number of cores and cache size affect processor performance.

    MOV R0, #0    MOV R1, #1loop:    ADD R0, R0, R1    ADD R1, R1, #1    CMP R1, #5    BLT loop    STR R0, 100    HALT

Trace this program (AQA instruction set) and state the value stored in memory location 100. Explain the purpose of the program.

Explain how a processor handles an interrupt.

Describe the role of each layer of the TCP/IP stack when a web page is requested.

A host has IP address 192.168.10.37 with subnet mask 255.255.255.192 (/26). State the network address, the broadcast address and the number of usable host addresses in the subnet.

Explain how digital signatures and digital certificates use asymmetric encryption to provide security.

A shop stores orders in one table: Order(OrderID, OrderDate, CustomerID, CustomerName, CustomerEmail, ProductID, ProductName, Price, Quantity) Normalise this to third normal form, showing the tables and keys.

Write an SQL query to list the names and prices of products costing more than £20, most expensive first.

Write an SQL query to show the total quantity of products ordered by the customer with email 'ana@example.com'.

Explain what is meant by atomicity and isolation in transaction processing.

Describe three characteristics of Big Data.

L = [3, 8, 1, 6]. State the result of: (a) map (*2) L, (b) filter (>5) applied to the result of (a), (c) fold (+) 0 applied to the result of (b). Explain one benefit of functional programming for Big Data.

A function add takes two integers and returns an integer. Write its type in the form used for functional programming and explain partial application.

Discuss the ethical, legal and cultural issues raised by police use of live facial recognition in public places.