Digital Sample Questions

1. An analog-to-digital converter provides a 12 bit digital output with a ±10 volt input. The resolution of the conversion process is:

1. 0.25%
2. 0.025%
3. 2.5%
4. 0.05%
5. 0.5%

2. A control system has a position sensor with a resolution of 1800 counts/revolution. The controller was required to stop at the position zero, but unfortunately the motor stopped at position -3 degrees instead. The controller filter has a proportional gain of 6 and the DAC gain is 80 millivolt/count. Under these circumstances, the DAC output voltage is:

1. 7.20 volts
2. 1.44 volts
3. 2.40 volts
4. saturates at 10 volts
5. 6.37 volts

3. Digital signal processor (DSP) ICs are increasingly popular in motion control applications primarily because...

1. they are optimized for fast repeated mathematical calculations
2. they usually have a very large address space for memory
3. they usually have a very large stack to handle multiple interrupt levels
4. they were designed explicitly for motion control
5. everything is going digital these days

4. A temperature transducer so that 0 mV corresponds to 0C and 10 mV corresponds to 10C is used to measure the temperature in a chamber that goes from 0 to 100C. What temperature can be resolved by an 8-bit analog to digital converter?

1. 0.39 C
2. 0.19C
3. 0.79C
4. 0.49C
5. 0.59C

5. If a microprocessor has 10 data pins, 12 address pins and 8 control pins, there are

1. 4096 memory locations
2. 1024 memory locations
3. 256 memory locations
4. 5120 memory locations
5. 2048 memory locations

6. The STD bus is characterized by

1. 56 pins, of which 8 are data and 16 are address pins
2. 100 pins, of which 8 are data and 16 are address pins
3. 96 pins, of which 32 are data and 32 are address pins
4. 62 pins, of which 8 are data and 20 are address pins
5. 80 pins of which 32 are data and 32 are address pins

7. When configuring the RS-232 interface as a null modem,

1. only pins 2, 3 and 7 are used
2. all 25 pins are needed
3. 2 and 7 are reversed
4. pin 12 (carrier detect) must be set and pin 22 (ring indicator) must be clear
5. pins 3 and 7 are reversed

8. The IEEE 488 parallel data bus is comprised of

1. controller, talker and listener lines.
2. data and a controller lines.
3. 8 data bus lines and 5 data transfer control bus lines
4. 16 data bus lines and 3 data transfer control bus lines
5. address and controller lines

9. A RAM device is 4K by 16 in size. How many data and address lines must there be?

1. 16 data, 12 address lines
2. 16 data line and 4096 address lines
3. 16 data lines and 12 address lines
4. 4 data lines and 16 address lines
5. 4 data lines and 12 address lines

10. A null modem is used for communication when two PCs are...

1. connected directly through the serial ports.
2. connected directly through the parallel ports.
3. connected indirectly by means of a LAN.
4. connected indirectly by means of a WAN.
5. connected via the Internet

11. The logic level for a 4-bit digital to analog converter (DAC) are 5 volts for logic 1 and 0 volts for logic 0. What voltage does the binary number 0101 correspond to?

1. 1.5625 volts
2. 3.125 volts
3. 0.3125 volts
4. 0.625 volts
5. none of the above

Page Revised: July 14, 2003