Advanced level 2024 centre regional mock computer science 2
Advanced level 2024 centre regional mock computer science 2
i. a) The access time for a device such as a magnetic disk is measured in three stages: seek time, rotational
delay (latency), & data transfer time. Explain what is meant by each of the underlined terms. (3 Marks)
b). Show how the denary value −9.125 can be represented in normalised floating-point format, using 8 bits for
the mantissa and 4 bits for the exponent, both in two‟s complement. (3 Marks)
ii.. A combinational logic circuit is designed to carry out addition in base 2. The circuit will add three bits A, B &
to produce a sum (S) and a carry ( ) as outputs.
a) What is a combinational logic circuit? (1 Mark)
b) Draw the truth table for addition in this circuit (2 Marks)
c) From the truth table above, obtain and simplify the Boolean expressions for the outputs Sum (S) and carry ( )
(4 Marks)
d) Implement the logic circuit above using only NAND gates (4 Marks)
