Microprocessors - Question and Answer - 10

46. What is Flag register in 8085 microprocessor?
The Flag register is a Special Purpose Register and is completely different from the other registers in a microprocessor. It consists of 8 bits and only 5 of them are useful in 8085. The other 3 are left vacant and are in the future Intel versions. Therefore, 8085 has five flags - Sign flag, Zero flag, Auxillary carry flag, Parity flag and the Carry flag.

47. What are level-triggering interrupt?
RST 6.5 & RST 5.5 are level-triggering interrupts. Level trigger interrupt means the interrupt will be in active mode for the duration of the signal and coming to the edge triggering, it will be activated just like switch(respond at positive or negative edge).

48. What are the flags in 8086?
In 8086 Carry flag, Parity flag, Auxiliary carry flag, Zero flag, Overflow flag, Trace flag, Interrupt flag, Direction flag, and Sign flag.

49. Which interrupt is not level-sensitive in 8085?
RST 7.5 is a raising edge-triggering interrupt.

50. What are Software interrupts?
RST0, RST1, RST2, RST3, RST4, RST5, RST6, RST7. Software Interrupt Definition. A software interrupt, also called an exception, is an interrupt that is caused by software, usually by a program in user mode. Examples of events that cause them are requests by an application program for certain services from the operating system or the termination of such programs.

51. What are the various flags used in 8085?
Sign flag, Zero flag, Auxiliary flag, Parity flag, Carry flag.


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