GATE EC Computer Organization questions

Practise Computer Organization questions for GATE EC. Explore official PYQs and original topic-wise quizzes, check answers and view available solutions. Free, no sign-in.

Track address sizes, cache organisation and pipeline dependencies carefully. Write down the units and assumptions before computing memory access times or processor performance.

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SubjectTopicYearType

The address of the first location of a

256

kilo byte

(\mathrm{KB})

memory is

(2500)_{\mathrm{H}}

. Choose the correct address of the last location of the memory.

A machine has a

32

-bit architecture with

1

-word long instructions. It has

24

registers and supports an instruction set of size

40

. Each instruction has five distinct fields, namely opcode, two source register identifiers, one destination register identifier, and an immediate value. Assuming that the immediate operand is an unsigned integer, …

The content of the registers are

R_{1} = 25H, R_{2} = 30H

and

R_{3} = 40H

. The following machine instructions are executed.

\text{PUSH } \{R_{1}\}

\text{PUSH } \{R_{2}\}

\text{PUSH } \{R_{3}\}

\text{POP } \{R_{1}\}

\text{POP } \{R_{2}\}

\text{POP } \{R_{3}\}

After execution, the content of registers

R_{1},\:R_{2},\:R_{3}

…

In an

8085

microprocessor, the number of address lines required to access a

16

K byte memory bank is ____________ .

The clock frequency of an

8085

microprocessor is

5

MHz . If the time required to execute an instruction is

1.4 \: \mu s

, then the number of T-states needed for executing the instruction is

The following FIVE instructions were executed on an

8085

microprocessor. MVI A,

33

H MVI B,

78

H ADD B CMA ANI

32

H The Accumulator value immediately after the execution of the fifth instruction is

In an

8085

system, a PUSH operation requires more clock cycles than a POP operation. Which one of the following options is the correct reason for this?

In an

8085

microprocessor, the contents of the accumulator and the carry flag are

A7

(in hex) and

0

, respectively. If the instruction

RLC

is executed, then the contents of the accumulator (in hex) and the carry flag, respectively, will be

In an 8085 microprocessor, the shift registers which store the result of an addition and the overflow bit are, respectively

In an

8085

microprocessor, which one of the following instructions changes the content of the accumulator?

Which one of the following

8085

microprocessor programs correctly calculates the product of two

8

-bit numbers stored in registers

B

and

C?

For the

8085

microprocessor, the interfacing circuit to input

8

-bit digital data

( DI_{0}-DI_{7})

from an external device is shown in the figure. The instruction for correct data transfer is

8085

microprocessor executes

“STA 1234H”

with starting address location

1FFEH

(STA copies the contents of the Accumulator to the

16

- bit address location). While the instruction is fetched and executed, the sequence of values written at the address pins

A_{15} – A_8

For

8085

microprocessor, the following program is executed.

\begin{array}{ll} & MVI\: A, 05H; \\ & MVI\: B, 05H; \\ PTR: & ADD \:B; \\ & DCR \:B; \\ & JNZ\: PTR; \\ & ADI\: 03H; \\ & HLT; \end{array}

At the end of program, accumulator contains

Following is the segment of a

8085

assembly language program

\text{LXISP,EFFFH}

\text{CALL 3000 H}

3000 \mathrm{H}: \mathrm{LXIH}, 3 \mathrm{CF} 4 \mathrm{H}

\text{PUSH PSW}

\text{SPIH}

\text{POP PSW}

\text{RET}

On completion of

\text{RET}

execution, the contents of

\mathrm{SP}

Statement for Linked Answer Questions 81 a and 81 b: Consider an

8085

microprocessor system The following program starts at location

0100 \mathrm{H}

\begin{array}{l} \text{LXI SP, 00FF} \\ \text{LXI H, 0701} \\ \text{MVI A, 20H} \\ \text{SUB M} \end{array}

The content of accumulator when the program counter reaches

0109 \mathrm{H}

The

8255

Programmable Peripheral Interface is used as described below. An A/D converter is interfaced to a microprocessor through

8255.

The conversion is initiated by a signal from the

8255

on Port C. A signal on Port C causes data to be strobed into Port A. Two computers exchange data using a pair of

8255 \mathrm{s}

. Port A works as a …

The number of memory cycles required to execute the following

8085

instructions

\text{LDA 3000 H}

\text{LXI D, FOF 1 H}

would be

Consider the sequence of

8085

instructions given below.

\text{LXI H, 9258, MOV A, M, CMA, MOV M, A}

Which one of the following is performed by this sequence?

It is desired to multiply the numbers

0 \mathrm{AH}

0 \mathrm{BH}

and store the result in the accumulator. The numbers are available in registers

B

and

C

respectively. A Part of the

8085

program for this purpose is given below:

\qquad \qquad \text{MV1 A, 00H}

\text{Loop;}…....……….….

\qquad.…...…….....….

…