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Memory mapped I/O and Isolated I/O

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As a CPU needs to communicate with the various memory and input-output devices (I/O) as we know data between the processor and these devices flow with the help of the system bus. There are three ways in which system bus can be allotted to them : Separate set of address, control and data bus to I/O and memory. Have common bus (data and address) for I/O and memory but separate control lines. Have common bus (data, address, and control) for I/O and memory. In first case it is simple because both have different set of address space and instruction but require more buses. Isolated I/O – Then we have Isolated I/O in which we Have common bus(data and address) for I/O and memory but separate read and write control lines for I/O. So when CPU decode instruction then if data is for I/O then it places the address on the address line and set I/O read or write control line on due to which data transfer occurs between CPU and I/O. As the address space of memory and I/O is isolated and the name is so....
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8237 Direct Memory Access (DMA) Controller

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 Basic DMA operation The direct memory access (DMA) I/O technique provides direct access to the memory while the microprocessor is temporarily disabled. A DMA controller temporarily borrows the address bus, data bus, and control bus from the microprocessor and transfers the data bytes directly between an I/O port and a series of memory locations. The DMA transfer is also used to do high-speed memory-to-memory transfers. Two control signals are used to request and acknowledge aDMA transfer in the microprocessor-based system. The HOLD signal is a bus request signal which asks the microprocessor to release control of the buses after the current bus cycle. The HLDA signal is a bus grant signal which indicates that the microprocessor has indeed released control of its buses by placing the buses at their high-impedance states. The HOLD input has a higher priority than the INTR or NMI interrupt inputs. The 8237 DMA controller The 8237 DMA controller supplies the memory and I/O with contro...
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Assignment Questions (Subject:- Microprocessor and Its Interfacing)

Microprocessor and Its Interfacing Assignment Questions   Instructions: ·          Solve any 8 questions in each section. ·          Make appropriate assumptions wherever necessary. Unit – I 1.       What is a microprocessor? What is a flag? Why are the program counter and the stack pointer 16-bit register? 2.       List the major features of 8085 microprocessor. 3.       List the allowed register pairs of 8085. 4.    What is microprocessor? Give the power supply & clock freqency of 8085 5.    List few applications of microprocessor-based system. 6.    What are the functions of an accumulator? 7.    List the 16 – bit registers of 8085 microprocessor. 8.    Define flags? What is the use of ALE? 9.       Explain the need to ...
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