GATE 2023 EE – Question 57

Analog and Digital Electronics · VCOs and timers, combinatorial and sequential logic circuits, multiplexers, demultiplexers · 2 marks · Numerical answer

In a given 8-bit general purpose micro-controller there are following flags.

C-Carry, A-Auxiliary Carry, O-Overflow flag, P-Parity (0 for even, 1 for odd)

R0 and R1 are the two general purpose registers of the micro-controller.

After execution of the following instructions, the decimal equivalent of the binary sequence of the flag pattern [CAOP] will be __________.

MOV R0, +0x60
MOV R1, +0x46
ADD R0, R1

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Correct answer: 2

Explanation

$0x60+0x46=0xA6=1010\,0110_2$. Carry out of bit 7: none, so $C=0$. Carry out of bit 3: $0+6=6$, none, so $A=0$. Overflow: $96+70=166>127$ as signed 8-bit, so $O=1$. Parity: $10100110$ has four 1s (even), so $P=0$. The pattern $[CAOP]=0010_2=2$.