1. Which of the following registers offers high impedance?
a) data register
b) data direction register
c) individual control bit
d) data register and data direction register
Explanation: The register which offers high impedance is the individual control bit or the third register which can be implemented by switching off both the buffers and putting their connections to the pin which offers high impedance.
2. Which of the following can be used as a chip select?
a) multifunction I/O port
b) parallel port
c) DMA port
d) memory port
Explanation: The multifunction I/O port can also be used a chip select for the memory design. The function that the pin performs is set up internally through the use of a function register which internally configures how the external pins are connected internally.
3. Which of the following is necessary for the parallel input-output port?
a) inductor
b) pull-up resistor
c) push-up resistor
d) capacitor
Explanation: The I/O port needs an external pull-up resistor. In some devices, it offers internally. If it is not provided, it can cause incorrect data on reading the port and it prevents the port from turning off an external device.
4. Which of the following can be described as general-purpose?
a) multifunction I/O port
b) input port
c) dma port
d) output port
Explanation: The multifunction I/O ports can be described as the general-purpose and it can be shared with other peripherals.
5. Which of the following helps in the generation of waveforms?
a) timer
b) inputs
c) outputs
d) memory
Explanation: The embedded systems have a timing component called timer or counter which helps in the timing reference for control sequence, provides system tick for the operating system and also helps in the generation of waveforms for the serial port baud rate generation.
6. Which bit size determines the slowest frequency?
a) counter size
b) pre-scalar value
c) counter
d) timer
Explanation: The pre-scalar value determines the slowest frequency that can be generated from a given clock input. Actually the bit size are determined by the pre-scalar value and the conuter size.
7. Which bit size determines the maximum value of the counter-derived period?
a) counter size
b) pre-scalar value
c) bit size
d) byte size
Explanation:The bit size are basically determined by its fundamental properties, that is, the pre-scalar value and the counter size. The counter size determines the maximum value of the counter derived period.
8. Which of the following timer is suitable for IBM PC?
a) IA-32
b) Intel 8253
c) Intel 64
d) 8051 timer
Explanation: The Intel 8253 timer is suitable for the IBM PC. IA-32 and Intel 64 are the offload timers used only for Intel. The 8051 timer is used for the timing program in 8051.
9. Which of the following is mode 0 in 8253?
a) interrupt on start count
b) interrupt for wait statement
c) interrupt on terminal count
d) no interrupt
Explanation: The interrupt on the terminal count is known as mode 0 for the 8253. An initial value is loaded into the count register and then starts to count down at the frequency which is determined by the clock input. When the count reaches zero, an interrupt is generated.
10. Which determines the mode 1 in the Intel 8253?
a) interrupt on terminal count
b) programmable one-shot
c) rate generator
d) square wave rate generator
Explanation: Programmable one-shot is also known as mode 1 in the Intel 8253. In mode 1, a single pulse with a programmable duration is created first and then the pulse length is loaded into the counter and when the external gate signal is high, the rising edge starts the counter to count down to zero and the counter output signal goes high to start the external pulse. When the counter reaches to zero, the counter output goes low and thus the ending of the pulse.