Two Marks Questions with Answers

Two Marks Questions with Answers

 

Q.1 What is an USART ?

Ans. : USART stands for universal synchronous/Asynchronous Receiver/Transmitter. It is a programmable communication interface that can communicate by using either synchronous or asynchronous serial data.

 

Q.2 What is the use of 8251 chip ?

Ans. : 8251 chip is mainly used as the asynchronous serial interface between the processor and the external equipment.

 

Q.3 What is the use of modem control unit in 8251?

Ans. : The modem control unit handles the modem handshake signals to coordinate the communication between the modem and the USART.

 

Q.4 What is TxD ?

Ans. : TxD - Transmitter Data Output. This output pin carries serial stream of the transmitted data bits along with other information like start bit, stop bits and priority bit.

 

Q.5 what is RxD ?

Ans. : RxD-Receive Data Input. This input pin of 8251A receives a composite stream of the data to be received by 8251A.

 

Q.6 Explain the working of receiver part of USART.

Ans. : USART receives data through RxD line. It can receive that in two basic modes : asynchronous reception and synchronous reception. Data reception can be enabled by setting receive command instruction.

 

Q.7 Write the format in which data is transmitted in asynchronous mode by 8251. AU : Dec.-07, May-14

 Ans. : The format in which data is transmitted in asynchronous mode by 8251 is as shown in the Fig.11.1

 

Q.8 Name the peripheral ICs used for parallel and serial data transfer.

8255 and 8251.

 

Q.9 What is baud rate ?

Ans. : The baud rate is the number of distinct symbol changes made to the transmission medium per second in a digitally modulated signal. It is used to identify that how much of the data had been transferred but at how much speed.

 

Q.10  Draw the 'Mode Word' and command word format of 8251 USART. AU : Dec.-11

(Refer section 11.5)

                  

Q.11  Draw the mode word format of 8251 USART. AU : Dec.-12

(Refer Fig. 11.5.1)         

                  

Q.12  What are the output terminals in USART 8251 ? AU : May-13

 (Refer Fig. 11.4.1)        

 

Q.13  How a keyboard matrix is formed in keyboard interface using 8279 ?

(Refer lab experiment 11.9.2) 

 

Q.14  What are the function of USART ? AU : Dec.-14

(Refer section 11.2)       

 

 

University Questions with Answers (Long Answered Questions)

 

(Regulation 2008)

May-11

Q.1 With neat block diagram, explain the architecture of 8251 USART. (Refer section 11.4)          [16]

Q.2 Explain the operation and programming of 8251 USART in detail. (Refer section 11.9)          [16]

Q.3 With functional block diagram, explain the operation and programming of 8251 USART in detail. (Refer section 11.4)      [16]

May-12

Q.4 Explain with a neat diagram the interfacing of 8251 to 8085 microprocessor. (Refer section 11.8)   [8]

May-13

Q.5 Draw and explain the functional block diagram of 8251 USART. (Refer section11.4) [8]

(Regulation 2013)

May-16

Q.6 Write a program to output square wave of 1 kHz frequency on the SOD pin of 8085 for 5 seconds. (Refer lab experiment 11.1.2)     [8]

Q.7 Draw and explain the functional block diagram of 8251. (Refer section 11.4)        [8]