Differentiate between RISC and CISC Architecture [4 marks]

RISC (Reduced Instruction Set Computer) uses simple, fixed-length instructions executed in one clock cycle, while CISC (Complex Instruction Set Computer) uses complex, variable-length instructions that may take multiple cycles.

Feature	RISC	CISC
Instructions	Simple, few in number	Complex, large in number
Instruction Length	Fixed length	Variable length
Execution Time	Single clock cycle	Multiple clock cycles
Addressing Modes	Few	Many
Design Philosophy	Hardware-oriented (hardwired)	Software-oriented (microprogrammed)
Registers	Large number of registers	Fewer registers
Examples	ARM, MIPS, SPARC	Intel x86, VAX

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Sub-question 1: Multiply 9 and 7 using Booth's Multiplication Algorithm [6 marks]

Booth's Algorithm is a multiplication algorithm that handles signed binary numbers using 2's complement representation and works by examining pairs of bits to decide add, subtract, or shift operations.

M = 01001, -M = 10111, Q = 00111, A = 00000, Q₋₁ = 0, n = 5

Cycle	A	Q	Q₋₁	Q₀ Q₋₁	Operation
Init	00000	00111	0	—	—
1	10111	00111	0	1 0 → A=A-M	Subtract
ASR	11011	10011	1		Shift
2	11011	10011	1	1 1 → No op	—
ASR	11101	11001	1		Shift
3	11101	11001	1	1 1 → No op	—
ASR	11110	11100	1		Shift
4	11110	11100	1	0 1 → A=A+M	Add
A+M	00111	11100	1
ASR	00011	11110	0		Shift
5	00011	11110	0	0 0 → No op	—
ASR	00001	11111	0		Shift

Result = A Q = 00001 11111

Verification: $00001\,11111$ in decimal = $00111111_2$ = 63

$$9 \times 7 = 63$$

Conclusion: Booth's algorithm correctly computes the product as 63 using addition, subtraction, and arithmetic shift right operations.