Microprocessors - Question and Answer - 9

41. Where does CPU Enhanced mode originate from ?
Intel’s 80386 was the first 32-bit processor, and since the company had to backward-support the 8086. All the modern Intel-based processors run in the Enhanced mode, capable of switching between Real mode (just like the real 8086) and Protected mode, which is the current mode of operation.

42. How many bit combinations are there in a byte ?
Byte contains 8 combinations of bits. There are two possible states in a bit, usually expressed as 0 and 1. A series of eight bits strung together makes a byte, much as 12 makes a dozen. With 8 bits, or 8 binary digits, there exist 2^8=256 possible combinations

43. What is Non-Maskable interrupts ?
An interrupt which can be never be turned off (ie. disabled) is known as Non-Maskable interrupt. In computing, a non-maskable interrupt (NMI) is a hardware interrupt that standard interrupt-masking techniques in the system cannot ignore. It typically occurs to signal attention for non-recoverable hardware errors. .Therefore, such interrupts should not be masked in the normal operation of the system.

44. What is the Maximum clock frequency in 8086 ?
5 Mhz is the Maximum clock frequency in 8086.

45. What is meant by Maskable interrupts ?
An interrupt that can be turned off by the programmer is known as Maskable interrupt.Maskable Interrupt: An Interrupt that can be disabled or ignored by the instructions of CPU are called as Maskable Interrupt. Eg: RST6. 5,RST7. 5,RST5. 5 OF 8085 are maskable Interrupts.

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