UNIT-IIIPart A- 8255

Fundamentals of Microprocessor and

Microcontroller

By, Prof. Tambe S. S.

S.N.D. College of Engineering and Research Center

Department of Electrical Engineering

Quiz Competition On

Q.1

The two widely used general-purpose programmable devices, can be compatible with ____ microprocessor

A] Only 8085

D] Almost Any Microprocessor

C] Only 8051

B] Only 8086

Q.2The signals exchanged between microprocessor and a peripheral prior to actual data transfer; these signals are__________

A] Control Signals

D] Data Transfer Signals

C] Status Signal

B] Handshake Signals

Q.3

A programmable I/O devices likely to have which of the following devices:

A] A control register in which the MPU can write an instruction

D] All of the aboveC] Handshake signals and interrupt logic

B] Chip Select Logic

Q.4

8255 has ________ I/O pins

A] 40

D] 28C] 24

B] 16

Q.5If chip select logic of 8255 is connected to the A7 line through NOT gate and A0 and A1 of 8255 connected to the A0 and A1 of the system address bus, then assuming A6 to A2 at logic 0, what will be the address of Port C ?A] 8020H

D] 28HC] 82H

B] 8002H

Q.6

I/O function or bit set/reset function of 8255 are classified by the_____ bit of control word register

A] D7

D] D6 and D5C] D6

B] D0

Q.7

Which of the following statements are true

A] Port C operates in the Bit set/reset mode

D] Both A and B are True

C] Both A and B are Wrong

B] BSR control word does not affect the function of Port A and B

Q.8

In which of the following modes, ports does not have handshake or interrupt capability

A] Mode 1

D] All of the aboveC] Mode 2

B] Mode 0

Q.9

Identify the Mode 0 control word to configure port A and port Cu as output ports and port B and port CL as input ports.

A] 83

D] 80C] 81

B] 82

Q.10

8255 is interfaced with 8085 in memory mapped I/O scheme. If this 8255 chip is selected when A15 line is high and A0 and A1

lines are used to select Port A, B, C and Control Word register then, assuming all don’t care address lines at logic 0, the address of Control Word register is:

A] 83H

D] 82HC] 8383H

B] 8003H

Q.11

If 8255 is interfaced in Memory mapped I/O scheme. The Addresses of Port A,B,C and CWR are 4000H,4001H,4002H and 4003H respectively, then which of the following instructions will configure the all the ports as output port in Mode0 ?

A] MVI A, 83H STA 4003H

D] MVI A, 80H LDA 4003H

C] MVI A, 80H STA 4003H

B] MVI A, 80H OUT CWR

Q.12

If the 8255 system is reset then:

A] It clears the control register

D] Only A and C.C] Sets all the ports in the input mode

B] Sets all the ports in the output mode

Q.13The addresses for Port A,B,C and CWR are 80H,81H, 82H and 83H respectively.MVI A, 80HOUT 83HXRA AOUT 82HORI 0FHOUT 83HWhat will be the content of Port C after execution of above instructions ?

A] 80H

D] 83H.C] 82H

B] 81H

Q.14

To set/reset bits in port C, a control word is written in to

A] Port C

D] Can’t be predictedC] Both A and B

B] Control word register

Q.15

A BSR Control word affects

A] Only Port A

D] All of above portsC] Only Port C

B] Only Port B

Q.16

In mode 0

A] 8 bits of Port A, B ,Cu and CL can be programmed as either input or output

D] Both B and CC] Port C as two 4-bit ports

B] Ports A and B are used as simple 8-bit I/O ports

Q.17

In mode 1

A] Two ports A and B function as 8-bit I/O ports

D] All of above C] Output data are latched

B] Input data are latched

Q.18

The bits of Port C used for handshaking when ports A is configured as input port in mode1 are:

A] PC0, PC1 and PC3

D] PC2, PC1 and PC0C] PC3, PC4 and PC5

B] PC4, PC5 and PC6

Q.19

In 8255 mode1, Which signal generated by a peripheral device to indicate that it has transmitted a byte of data?

D] INTEC] INTR

B] IBFA] STB

Q.20

A control word to set up Port A as input and Port B as output in Mode 1 is

D] Can’t be predicted

C] 4B

B] C4A] B4

Q.21

8255 has ______parallel ports

D] Three 8- bitC] Two 4 bit

B] Two 8- bitA] Three 4-bit

Q.22

8255 has _____ I/O modes

D] 4C] 1

B] 2A] 3

Q.23

A high on _____ line causes all 24 lines of three 8 –bit ports to be in the input mode.

D] RDC] GND

B] RESETA] WR

Q.24

If______, the control word is taken as a I/O mode definition word

D] D0 = 0C] D0 = 1

B] D7 = 0A] D7 = 1

Q.25

If______, the control word is taken as a Bit set/reset word

D] D0 = 0C] D0 = 1

B] D7 = 0A] D7 = 1

Q.26

On activation of _____, the 8255 loads data from the input port lines into the input buffer of that port.

D] None of the above

C] OBF

B] IBFA] STB

Q.27

8255 sets INTR when STB, IBF and INTE for input control signals are ________ respectively

D] 0, 1 and 1C] 1, 1 and 1

B] 1, 1 and 0A] 1, 0 and 1

Q.28

Which of the following port can be programmed in Mode 0,1 and 2 ?

D] Both A and BC] Port C

B] Port BA] Port A

Q.29

_____ is a general purpose programmable I/O device used for parallel data transfer.

D] 8051C] 0808

B] 8255A] 8254

Q.30

Mode 1 of 8255 I/O mode is:

D] None of theseC] Both A and B

B] Simple input/output

A] Input/output with handshake

Q.31

Which of the following mode of 8255 is Strobed Bi-directional I/O?

D] BSR ModeC] Mode 1

B] Mode 2A] Mode 0

Q.32

What is the status of port bit if it is configured as an output port?

D] 00C] 0

B] 11A] 1

Q.33

What is the status of A1, A0 during an input read or output write operation with port B?

D] 01C] 10

B] 11A] 00

Q.34

Port A and lower nibble of Port C come under ____ Group.

D] None of theseC] C

B] BA] A

Q.35

Which of the following port can be programmed nibble wise (separately)?

D] None of theseC] Port C

B] Port BA] Port A

Q.36

What type of control signal is IBF in mode 1?

D] None of theseC] Input/output

B] OutputA] Input

Q.37

What type of control signal is INTR in mode 1?

D] None of theseC] Input/output

B] OutputA] Input

Q.38

What is the size of I/O ports in 8255 ?

D] 1 bitC] 4 bits

B] 16 bitsA] 8 bits

Q.39

The status of A1 –A0 to select the CWR must be

D] 11C] 10

B] 01A] 00

Q.40

In 8255 RESET pin is used for ______.

D] resetting 3 portsC] resetting 8085

B] resetting CWRA] resetting CWR and 3 ports

Q.41

In 8255 _____ are 8 bit bi-directional I/O pins used to send data to peripheral or to read data from peripheral.

D] All of theseC] PC0 – PC7

B] PB0 –PB7A] PA0 –PA7

Q.42

Group A signals of 8255 consists of _______

D] Port A, B and CC] Port Cu and Port A

B] Port B and Port Cupper

A] Port A and Port B

Q.43

In BSR mode what will be bit pattern of CWR for setting PC3 bit

D] 0xxx0110C] 1xxx0111

B] 011xxx11A] 0xxx0111

Q.44

BSR mode in 8255 is for

D] All of theseC] Port C

B] Port BA] Port A

Q.45

The control word to set bit 4 of port C is_______.

D] 40HC] 90H

B] 04HA] 09H