COA Quiz-2

An instruction at address 021 in the basic computer has I = 0, an

operation code of AND instruction and an address part equal to

083. The memory word at address 083 contains 0002(Hex) and

the content of Accumulator is 0004(Hex). What will be the

content of Accumulator after execution of instruction.

• 0001

• None

• 0000

• 0006

Answer explanation

The AND operation between 0004 (Accumulator) and 0002 (memory) results in 0000, as only the bits that are 1 in both numbers remain 1. Thus, the content of the Accumulator after execution is 0000.

The content of Accumulator in basic computer is hex A937. The

initial value of E is 1. The initial value of PC is 021. Determine the

content of IR while execution of CLA instruction.

• 7800

• 0000

• A937

• 7020

Answer explanation

The CLA instruction clears the accumulator. During its execution, the content of the Instruction Register (IR) is set to the value of the Accumulator before clearing, which is A937. Thus, the content of IR is A937.

Consider the following program for the Basic Computer.
What will be the final content of the accumulator (AC) after execution of the program?

010 CLA

011 ADD 016

012 BUN 014

013 HLT

014 AND 017

015 BUN 013

016 C1A5

017 93C6

• 93C6

• None

• 8184

• C23D

Answer explanation

The program initializes AC to 0, adds the value at address 016 (C1A5), jumps to 014, performs AND with 017 (93C6), and then returns to HLT. The final value in AC is 8184 after the AND operation.

Consider the following program written for the Basic Computer.
After execution of the program, what will be the final value stored in memory location CTR?

CLE

CLA

STA CTR

LDA WRD

SZA

BUN ROT

BUN STP

ROT, CIL

SZE

BUN AGN

BUN ROT

AGN, CLE

ISZ CTR

SZA

BUN ROT

STP, HLT

CTR, HEX 0

WRD, HEX 62C1

END

• 0006

• 3231

• 62C1

• 0040

Answer explanation

The program increments CTR each time it loops through the instructions until WRD (62C1) is zero. The final value in CTR after all iterations is 0006, as it counts the number of bits shifted.

The content of Accumulator in basic computer is hex A937. The

initial value of E is 1. The initial value of PC is 021. Determine the

content of IR while execution of CLA instruction.

• 7800

• 0000

• A937

• 7020

Answer explanation

The CLA instruction clears the accumulator. The content of the Instruction Register (IR) is formed by combining the opcode for CLA (78) with the address from the Program Counter (PC, 021), resulting in 7800.