Peripheral interface

The signal that may be used either to interrupt the CPU or polled by the CPU is

• TXRDY(Transmitter ready)
• DSR(active low)
• RXRDY(Receiver ready output)
• DTR(active low)

If 02H is loaded into 8251A mode word register, which of the following is correct?

• 8251A operates in synchronous mode
• 8251A operates in asynchronous mode with baud rate factor of 16
• 8251A operates in asynchronous mode with baud rate factor of 1
• 8251A operates in asynchronous mode with baud rate factor of 64

……….line is made high & sync characters are transmitted on TxD line

• RxRDY
• TxRDY
• TxE
• None of these

When modem is ready for data transmission/reception it generate a signal…………to indicate it’s readiness for data transfer

• DTR
• CTS
• DSR
• BOTH A & C

If the transmitter clock frequency of 8251A is 153.6kHz and the baud rate in asynchronous mode is 2400, the baud rate factor is

• 1
• 16
• 32
• 64

The signals AEN and ADSTB of 8237A are used to latch a

• Lower order address byte<br /> <br /> <br />
• Higher order address byte
• Lower order data byte
• Higher order data byte

If 0FH is loaded into control word register of 8254, then the mode selected would be

• Mode 2
• Mode 3
• Mode 4
• Mode 5

If the chip select of 8254 is generated using the address of counter 2 would be

• 48h
• B5h
• B6h
• B7h

In order to generate 1 KHz square wave using 8254 operated at 2 MHz clock, the count that must be loaded into counter would be

• 03FFH
• 7D0H
• 1000H<br />
• 2000H

If the address of 8254 control word register is 97H, the address of counter 0 would be

• 96H
• 95H
• 94H
• 93H