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Micro Processor Interview Questions - Part 3


Where is the READY signal used ?

READY is an input signal to the processor, used by the memory or input/output devices to get extra time for data transfer or to introduce wait states in the bus cycles.

Give some examples of port devices used in 8085 microprocessor based system ?

The various port devices used in 8085 are 8212,8155,8156,8255,8355,8755.

What is the need for timing diagram ?

The timing diagram provides information regarding the status of various signals, when a machine cycle is executed. The knowledge of timing diagram is essential for system designer to select matched peripheral devices like memories, latches, ports etc from a microprocessor system.

What operation is performed during first T-state of every machine cycle in 8085 ?

In 8085, during the first T-state of every machine cycle the low byte address is latched into an external latch using ALE signal.

What is interrupt acknowledge cycle ?

The interrupt acknowledge cycle is a machine cycle executed by 8085 processor to get the address of the interrupt service routine in order to service the interrupt device.

What is vectored and non-vectored interrupt ?

When an interrupt is accepted, if the processor control branches to a specific address defined by the manufacturer then the interrupt is called vectored interrupt. In Non-vectored interrupt there is no specific address for storing the interrupt service routine. Hence the interrupted device should give the address of the interrupt service routine.

List the software and hardware interrupts of 8085 ?

  • Software interrupts : RST 0,RST 1,RST 2,RST 3,RST 4,RST 5,RST 6,RST 7
  • Hardware interrupts : TRAP,RST 7.5,RST 6.5,RST 5.5, INTR.

    What is TRAP ?

    The TRAP is a non-maskable interrupt of 8085. It is not disabled by processor reset or after recognition of interrupt.

    How clock signals are generated in 8085 and what is the frequency of the internal clock ?

    The 8085 has the clock generation circuit on the chip but an external quartz crystal or LC circuit or RC circuit should be connected at the pins X1 andX2. The maximum internal clock frequency of 8085 is 3.03MHz.

    Define stack ?

    Stack is a sequence of RAM memory locations defined by the programmer.

    Micro Processor Interview Questions - Part 4 >>>




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