PROGRAMMABLE DMA CONTROLLER – INTEL It is a 40 pin IC and the pin diagram is, The functional block diagram of is shown in fig. mode set register, and a terminal count register and it can also program, control registers of DMA controller, through the data bus. Pin Diagram of Outputs. The Intel is a 4-channel direct memory access (DMA) controller. It is specifically designed . Block Diagram Showing DMA. Channels.

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Microprocessor – 8257 DMA Controller

Micro-Controller Overview -Micro-controller overview. It is designed by Intel to transfer data at the fastest rate. Then the microprocessor tri-states all the data bus, address bus, and control bus. It is active low ,tristate ,buffered ,Bidirectional lines. In the master mode, it is used to load the data to the peripheral dkagram during DMA memory read cycle.

Microprocessor 8257 DMA Controller Microprocessor

These are the active low DMA acknowledge output lines. Survey Most Productive year for Staffing: In the active cycle IOR signal is used to access data from a peripheral and IOW signal is used to send data to the peripheral.


Pin Diagram of and Microprocessor. In the slave mode, they act as an riagram, which selects one of the registers to be contrroller or written. This signal is used to demultiplex higher byte address and data using external latch.

The maximum frequency is 3Mhz and minimum frequency is Hz. It is the active-low three state signal which is blocl to write the data to the addressed memory location during DMA write operation.

As seen in the above diagram these are the four individual asynchronous channel DMA request inputs, which are used by the peripheral devices to obtain DMA services. It is the low memory read signal, which is used to read the data from the addressed memory locations during DMA read cycles.

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How to design your resume? Analogue electronics Practice Tests. In the master mode, it also helps in reading the data from the peripheral devices during a memory write cycle.

Used to split data and address line. Top 10 facts why you need a cover letter? By crescent Follow User. It cojtroller a asynchronous input line. In the master mode, it is used to read data from the peripheral devices during a memory write cycle. It is used to receiving the hold request signal from the output device.



Mode set register is programmed by the CPU to configure whereas the status register is read by CPU to check which channels have reached a terminal count condition and status of update flag. This signal is used to convert the higher byte of the memory address generated by the DMA controller into the latches.

Microprocessor Interview Questions. The update flaghowever, is not affected by a status read operation. During DMA cycles these lines are used to blick the most coontroller bytes of the memory address from one of the. Instruction Set of Microprocessor.

This signal is used to convert the higher byte of the memory address generated diwgram the DMA controller into the latches. It is a write only registers. In the slave mode, it is connected with a DRQ input line Used to clear mode set registers and status registers A0-A3: These are the four least significant address lines.