Serial Interface Quiz

07/20/2001

Carefully choose the "most correct" answer, if there appears to be more than one !

* The "RS-232C Standard" refers to

  1. The IEEE standard description of the signals for parallel data transmission between two computers .
  2. The IEEE standard description of the pinouts and voltages for one method of serial data transfer.
  3. The proper method of handling 232mv "Receive/Send Communications".
  4. Version #2.32 of the IEEE RS-Carrier procedure.

* The acceptable voltage range of the IEEE RS-232C Interface is

  1. +/- 5V to +/- 15V (unloaded)
  2. +/- 3V to +/- 15V (loaded)
  3. +/- 3V to +/- 25V (loaded)
  4. +/- 5V to +/- 25V (unloaded)

* "DCE" is the acronym for

  1. Data Carrier Envelope
  2. Data Carrier Error
  3. Data Communications Equipment
  4. Data Control Entry

* "DTE" is the acronym for

  1. Digital Transmission Equipment
  2. Data Transfer Error
  3. Decode Transmission Error
  4. Data Terminal Equipment

* A "Baud Rate" of 1200 refers to

  1. Approximately 1.200 KHz serial data bit transfer rate
  2. 1200 Bytes/sec data transfer rate
  3. 1200 Bauds/sec data transfer rate
  4. Approximately 1200 Bytes/sec serial data transfer rate

* In "RS-232C" data transmission, an ASCII Character is transmitted over the lines

  1. As Negative-True Logic Signals, with the least significant bit first
  2. As Positive-True Logic Signals, with the most significant bit first
  3. As Negative-True Logic Signals, with the most significant bit first
  4. As Positive-True Logic Signals, with the least significant bit first

* When no data is present on an RS-232C cable, the Transmit-Data or Receive-Data lines

  1. Should be at 0V
  2. Rest at +V
  3. Rest at -V
  4. Are in a constant state of flux (transitions)

* The bit preceding the ASCII data bits is called

  1. The "Start-Bit", as a positive-voltage
  2. The "Sync-Bit", as a negative-voltage
  3. The "Lead-Bit", as a negative-voltage
  4. The "Stop-Bit",. as a positive-voltage

* The "Stop-Bits" refer to the

  1. The "Dead-Time" after the ASCII Character has been sent, to allow time for re-synchronization.
  2. Bits that have been sent to indicate that the data transmission has been prematurely terminated
  3. A request from the "Receiving-Unit" to hold off on further transmission.
  4. A series of serially transmitted bits to indicate that the transmitted message is complete and therefore "Stopped".

* The most commonly used RS-232C voltages are

  1. +/- 12V
  2. +/- 15V
  3. +/- 3V
  4. +/- 9V

* The chips most commonly used for TTL/RS-232C voltage level conversion interface are

  1. The 74188/74189
  2. The 1488/1489
  3. The 7812/7912
  4. The 75118/75119

* Connecting a "DCE" to a "DCE"

  1. Should not be tried
  2. Requires a "Straight-Cable"
  3. Requires a "Centronics" type of ribbon connector on each end
  4. Requires a "Null-Modem"

* Connecting a "Modem" to the serial port of an IBM (or Clone),

  1. Requires a "Straight-Cable", with DB-25M connectors on both ends
  2. Requires a "Null-Modem", with DB-25M connectors on each end
  3. Requires a "Crossed-Cable", with a DB-25M on one end, and a DB-25F on the other
  4. Requires a "Straight-Cable", with a DB-25F on one end, and a DB-25M on the other

* A "Null-Modem" is

  1. A device to insure that a series of "NULLS" are sent at appropriate times to a "Modem"
  2. Simply a crossed cable
  3. A device that prevents accidentally "Nulling-Out" Modem Transmissions
  4. An electronic device to prevent any "nulls" from occurring, during interfacing between a computer and a Modem

* The "Handshake-Lines" between RS-232C Interfaced Devices

  1. Are to communicate to the "Receiver" that the "Sender" is ready to send data
  2. Are to communicate to the "Sender" that the "Receiver" is ready to receive data
  3. May be used by the "Sender" to enable controls on the "Receiver-Unit"
  4. All of the above statements are true
  5. Only statements 1 and 2 above are valid

* The description "DCE"

  1. Can only refer to a specific type of equipment
  2. Can refer to a "Configuration" of equipment for I/O
  3. Refers specifically to equipment such as plotters and printers.
  4. Is the acronym for "Data Communications Equipment"
  5. Answer #4 and #2 both apply

* The terms "XON/XOFF" are

  1. A form of communications software "Protocol"
  2. Only used for local interfacing between computers
  3. Are commonly used between computers and parallel printers
  4. Are a form of indication that the transmission device is currently "On" (or "Off")

* The terms "ETX/ACK" are used

  1. By the Sender to request "Extending Transmission" to the Receiver, and the Receiver to "Acknowledge" that request.
  2. A method of the "Sender" to request a reply from the "Receiver" when completed with the block of data sent.
  3. To indicate that the "End-of-Text" for the entire message has been sent, with the Receiver acknowledging that signal from the Sender.
  4. For the Receiver to "Acknowledge" to the "Sender" that "End-of-Text" is ready to be received.

* The Handshake Lines that are said to be "Complementary" are

  1. pins 3 and 4
  2. pins 5 and 6
  3. pins 4 and 5
  4. pins 2 and 3

* Serial RS-232C Cable Lengths are usually limited to a length of

  1. 200 ft at 9600 Baud
  2. 50 ft at 9600 Baud
  3. 15 ft between a Computer and a Peripheral
  4. 30 ft at 2400 Baud

* Parallel TTL Printer Interface Cables should be limited to

  1. 6 ft between the Computer and the Printer
  2. 25 ft between the Computer and the Printer
  3. Not more than 10 to 12 ft between the Computer and the Printer
  4. Up to, but not exceeding 50 ft

* Parallel Interfacing between a Computer and a Printer

  1. Allows rapid "Baud-Rate" data transfer
  2. Allows for higher Printer "Through-put" than Serial
  3. Allows more rapid data-transfers than Serial within the same time frame
  4. Is more expensive than Serial-Data-Transfer

* Serial Interfacing between a Computer and a Peripheral

  1. Allows less data-lines, and over longer distances than parallel interfacing
  2. Is less expensive hardware than parallel interfacing
  3. Requires more elaborate cabling than parallel interfacing
  4. Can only be accomplished over very short distances (6 to 12 ft)

* In the "Centronics" parallel printer interface between an IBM/PC (or Clone) and the printer,
   the "Strobe" signal

  1. Is a "TTL Negative-Level" pulse
  2. Is a "TTL Positive-Level" pulse
  3. Is a 1 second transition from 0V to ~ +5V
  4. Is a "TTL pulse transition" from ~+5V to ~0V

* In the "Centronics" parallel printer interface between an IBM/PC (or Clone) and the printer,
   the "ACK" signal

  1. Is returned from the printer as a "TTL transition", from ~+5V to ~0V
  2. Is only returned by the printer, after receipt of an "ETX" signal from the computer.
  3. Is returned by the printer to the computer as a 0.5 second positive pulse (~5V)
  4. Is only returned by the printer, if correct ASCII characters have been received

* "Escape-Code-Sequences"

  1. Are only used to cause an "Escape" from Error Conditions
  2. Can be used to cause a printer to select a different font cartridge
  3. Can be used to cause a printer to change to a different character pitch size
  4. Both #2 and #3 are correct

*A 7-conductor shielded cable, with DB-25M connectors on each end would likely be used as

  1. a serial extension cable for an IBM/PC (or Clone)
  2. a parallel printer cable for an earlier type of computer
  3. a plotter cable for a non-IBM/PC type of computer
  4. a cable for between a modem and an IBM/PC (or Clone)

* A "straight-cable" that has a DB-25F connector on one end, and a DB-25M connector on the other end,

  1. could be used for between an IBM/PC (or Clone) and a plotter
  2. is probably to be used between a non-IBM/PC computer and a plotter
  3. might be used for between an IBM or Clone and a modem
  4. is probably intended for use between a non-IBM/PC computer and a printer.

* The type of Interface cable normally used for between an IBM/PC and most parallel printers

  1. would require a 36-pin male "Ribbon-Connector" on one end, and a DB-9F on the other end
  2. would require a DB-25F connector on one end, and a DB-25M on the other end
  3. would require a 36-pin male "Ribbon-Connector" on one end, and a DB-25M on the other end
  4. would require a DB-25M connector on one end, and a DB-25M connector on the other

* Interfacing an IBM/PC or Clone to a modem, requires

  1. a straight cable, with DB-25M connectors on both ends
  2. a crossed cable, with a DB-9F connector on one end, and a DB-25M connector on the other end
  3. a straight cable, with a "NULL-MODEM" between the two pieces of equipment
  4. a straight cable, with a DB-25F connector on one end, and a DB-25M connector on the other end