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Little Man Computer :: Examination Questions :: GCE A Level Computing

The following is a program written using the Little Man Computer instruction set.

start	LDA	one
	OUT
	LDA	zero
	OUT
	LDA	count
	SUB	one
	STA	count
	BRP	start
	HLT
one	DAT	1
zero	DAT	0
count	DAT	3

(a) Describe the difference between the STA and LDA instructions. [2]

(b) Identify the type of memory addressing the program uses. [1]

(c) State the output this program generates. [3]

(e) Explain, giving an example, how pipelining in a CPU could speed up the execution of this program. [3]

(f) Describe one issue the line BRP start may cause for a CPU using pipelining. [2]

(g) Pipelining is one factor that affects the performance of a CPU. Identify one other factor. [1]