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                                   CHAPTER TWO ANSWERS TO REVIEW QUESTIONS

 1. A bit is the smallest unit of information used in modern computers. Bit stands for binary digit.

 2. The baud rate of a transmission line using dibits and transmitting at 28,800 bps is 14,400. If tribits were used, then the baud rate would be 9,600.

 3. The bandwidth of a transmission line transmitting in the frequency range of 4,000MHz to 6,500 MHz is 2,500 Hz

 4. KHz is 1,000 Hz, MHz is 1,000,000 Hz, GHz is 1,000,000,000 Hz.

 5. Continuous, discrete.

 6. Analog.

 7. An external modem connects by using a wire; an internal modem is a card plugged into the computer, and a null modem is used for short distance connections between computers.

 8. The function of a modem is to convert digital signals to analog and vice versa, so data can be transmitted over telephone lines.

 9. ISDN.

 10. A modem would be constructed to operate at different baud rates to permit usage on many networks, which may require different transmission speeds.

 11. A modem eliminator would be the least expensive way to connect two computers 25 feet apart.

 12. A 56,000 bps modem can transmit at the following speeds: 56,000 bps, 33,600 bps, 28,800 bps, 14,400 bps, 9,600 bps.

 13. The Baudot code is data code made up of five bits and 64 characters.

 14. Extended ASCII and EBCDIC both can create 256 characters. In comparing the tables, it is noted there are no gaps in the ASCII table but such gaps do exist in the EBCDIC table. The collating sequence of EBCDIC would be affected if the gaps were ever filled in. Mathematical manipulation of ASCII is easier because no gaps exist between the characters.

 15. ACK acknowledgment
  NAK negative acknowledgment
  SOH start of header
  EOT end of transmission
  ENQ enquiry
  SYN synchronize

 16. The sound waves that a person’s voice makes cause vibrations, which in turn cause the diaphragm to vibrate. The diaphragm is connected to a chamber filled with carbon, which compresses, causing more current to flow through the circuit. This causes an electrical signal on the line.

 17. Converter.

 18. because they are the same thing.

 19. A trunk in the telephone system is where the telephone lines connect end offices.

 20. Tandem offices handle long-distance calls within an area code, while toll offices are used between area codes.