Test: Timer - Computer Science Engineering (CSE) MCQ

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.

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.

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.

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.

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.

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.

Explanation: Mode 1 of the Intel 8253 can provide pulse width modulation for the power control where the gate is connected to a zero crossing detector or a clock source.

Explanation: The rate generator is the mode 3 in Intel 8253 timer. The square wave generator is the mode 4 and the hardware triggered strobe is the mode 5 in the Intel 8253 timer.

Explanation: The rate generator mode is determined by the mode 3 with the Intel 8253. It is a simple divide by N mode where N is the initial value loaded into the counte

Explanation: The mode 4 is the square wave generator. This mode is similar to the mode 3 except that the waveform is a square wave.

Explanation: The software triggered strobe can be used as a software-based watchdog timer in which the output is connected to a non maskable interrupt.

Explanation: The mode 5 or the hardware triggered strobe is similar to the mode 4 or the square wave rate generator expect that the retriggering is done by the external gate pin.

Explanation: The Intel 8253 timer has no interrupt pins. Therefore, the timer OUT pin is used to generate an external interrupt signal.

Explanation: The Intel 8253 and 8254 have same pin configuration and functions. 8051 timer is a programmable timer in the 8051 microcontroller. The MC68230 timer developed by Motorola can provide a powerful timer architecture which can provide higher resolution than the Intel 8253.

Explanation: The MC68230 timer have a 24-bit architecture which is splits into three 8-bit components because of the 8-bit bus in the MC68000 CPU.

Explanation: The MC68230 timer have a 24-bit architecture which is splits into three 8-bit components because of the 8-bit bus which is used for the communication with the host processor like MC68000 CPU which have an 8-bit architecture.

Explanation: Intel 8253 and 8259 are timers or counters which supports the processors. MC146818 is a real-time clock. MC68332 which is developed by Motorola is a 32 bit timer processor which can support MC68020.

Explanation: The running frequency of the MC68332 is 16 MHz.

Explanation: The 8253, 8254 and 8259 are timers or counters developed by Intel whereas MC146818 is a real-time clock.