Microprocessors - Question and Answer - 3

11. What is a Microprocessor ?
A microprocessor is a computer processor that incorporates the functions of a central processing unit on a single integrated circuit of MOSFET construction.. Microprocessor is a program-controlled device, which fetches the instructions from memory, decodes and executes the instructions. Most Micro Processor are single- chip devices.

12. What is the difference between primary & secondary storage device?
Difference between Primary storage and secondary storage. Primary memory is the main memory (Hard disk, RAM) where the operating system resides. Secondary memory can be external devices like CD, floppy magnetic discs etc. secondary storage cannot be directly accessed by the CPU and is also external memory storage.

13. How does a microprocessor work?
The microprocessor follows a sequence: Fetch, decode and then execute.The instructions are stored in the memory in a sequential order. The microprocessor fetches those instructions from the memory, then decodes it and executes those instructions till STOP instruction is reached. It then sends the result in binary to the output port. The task of the register is to store data temporarily and ALU performs the computing functions.

14. Give example for Non-Maskable interrupts?
Non-maskable interrupt is a hardware interrupt that cannot be disabled or ignored by the instructions of CPU. Examples of non-maskable interrupt include RST1, RST2, RST3, RST4, RST5, RST6, RST7 and TRAP of 8085 microprocessor
Trap is known as Non-Maskable interrupts, which is used in emergency condition.

15. What is Tri-state logic ?
Three-state, tri-state, or 3-state logic allows an output port to assume a high impedance state, effectively removing the output from the circuit, in addition to the 0 and 1 logic levels. This allows multiple circuits to share the same output line or lines. Three Logic Levels are used and they are High, Low, High impedance state. The high and low are normal logic levels & high impedance state is electrical open circuit conditions. Tri-state logic has a third line called enable line.

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