21. Which can prevent the terminal of data transmission?
A. flow control
B. increasing flow
C. increasing count
D. terminal count
Answer: A
The flow control can prevent data transmission. It can also prevent the computer from sending more data than the other can cope with.
22. Which of the following is the first flow control method?
A. software handshaking
B. hardware handshaking
C. UART
D. SPI
Answer: B
The first flow control method is the hardware handshaking in which the hardware in the UART detects the potential overrun and it will assert a handshake line to tell the other UART to stop the transmission.
23. Which one of the following is the second method for flow control?
A. hardware
B. peripheral
C. software
D. memory
Answer: C
In the first method of flow control, there is a chance of data loss. So the second method of flow control is adopted which uses software to send characters XON and XOFF. XOFF can stop the data transfer and XON can restart the data transfer.
24. Which can restart the data transmission?
A. XON
B. XOFF
C. XRST
D. restart button
Answer: A
The second method of flow control is called software which is based on certain characters called XON and XOFF. XOFF can stop the data transfer and XON can restart the data transfer.
25. Which of the following is a common connector?
A. UART
B. SPI
C. I2C
D. DB-25
Answer: D
There are two connectors that are used very commonly. They are DB-25 and DB-9 which have 25 pins and 9 pins respectively.
26. What does pin 22 in DB-25 indicate?
A. transmit data
B. receive data
C. ring indicator
D. signal ground
Answer: C
The 22nd pin in DB-25 and the 9th pin in the DB-9 indicates a ring indicator which is asserted when a connected modem has detected an incoming call.
27. Which pin indicates the DSR in DB-25?
A. 1
B. 2
C. 4
D. 6
Answer: D
The 6th pin in DB-25 indicates DSR, that is, data set ready which indicates that each side is powered on and is ready to access data.
28. Which of the following connections are one to one?
A. Modem cables
B. SPI
C. UART
D. I2C
Answer: A
The modem cables are straight cables that allow one-to-one connections without crossover.
29. Which of the following are used to link PCs?
A. modem cable
B. null-modem cable
C. serial port
D. parallel port
Answer: B
The modem cables are used to link the PC with other peripherals like printers, plotters, modems, etc. But it cannot link with other PCs. So an alternative method is adopted to link PCs which is called null-modem cable.
30. Which of the following method is used by Apple Macintosh?
A. hardware handshaking
B. software handshaking
C. no handshaking
D. null-modem cable
Answer: B
The Apple Macintosh and UNIX use software handshaking for the data transmission where the characters are sent to control the flow of characters between two systems.
