DMA stands for 4-channel Direct Memory Access. It is specially The following image shows the pin diagram of a DMA controller −. _pin. 3S. Da. Do,. Doack o. DOACK 1. Do,. Figure 1. Block Diagram. Figure 2. Pin Configuration. MO0€. HAO -. HLDA -. PAIORITY. AE SOLVEA. ME WW -. AEN -. ADSTE -. INTERNAL. Bus. MAAK. Figure 1. Block Diagram. Figure 2. Pin Configuration. 2-

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After reset the device is in the idle cycle. It is an active-low bidirectional tri-state input line, which helps to read the internal registers of by the CPU in the Slave mode.

These lines can also act as strobe lines for the requesting devices. This signal is used to convert the higher byte of the memory address generated by the DMA controller into the latches.

When CPU is having control of system bus it can access contents of address register, status register, mode set register, and a terminal count register and it can also program, control registers of DMA controller, through the data bus. It is used for requesting CPU to get the control of system bus. This signal is used to receive the hold request signal from the output device.

Pin Diagram of | Block Diagram of | Mode Set Register | Status Register

This is active high signal concern with the completion of DMA service. It is an active-low chip select line. Data Bus D 0 -D 7: These are active low bi-directional signals. In the slave mode, it is used to transfer data between microprocessor and internal registers of Therefore, for N number of desired DMA cycles it is necessary to load the value N-1 diaram the low order bits of the terminal count register.


Making a great Resume: The update flaghowever, is not affected by a status read operation.

It specifies the address of the first memory location to be accessed. Read This Tips for writing resume in slowdown What do employers look for in a resume? Pin Diagram of Microcontroller. In the master mode, these lines are used to send higher byte of the generated address to the latch. It is the active-low three state signal which is used to write the data to the addressed memory location during DMA write operation.

In the slave mode, it is connected with a DRQ input line Jobs in Meghalaya Jobs in Shillong. It is the hold acknowledgement signal which indicates the DMA controller that the bus has been granted to the requesting peripheral by the CPU when it is set to 1.

This active high signal clears, the command, status, request and temporary registers. How to design your resume? These are bi-directional tri-state signals connected to the system data bus.


Most significant four bits allow four different options for the Pin Diagram of TC bit remains set until the status register is read or the is reset. These are active low tri-state signals. 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 82577 condition and status of update flag.

It is designed by Intel to transfer data at the fastest rate. The four least significant lines A 0 -A 82257 are bi — directional tri — state signals. Digital Communication Interview Questions.

Microprocessor – 8257 DMA Controller

Pin Diagram of and Microprocessor. Interview Tips 5 ways to be authentic in an interview Tips to help you face your job interview Top 10 commonly asked BPO Interview questions 5 things you should never talk in any job interview Best job interview tips for job seekers 7 Tips to recruit the right candidates in 5 Important interview questions techies fumble most What are avoidable questions in an Interview?

In the slave mode, they perform as an input, which selects one of the registers to be read or written.