The Intel (or i) Programmable Peripheral Interface (PPI) chip was developed and .. In this mode, the may be used to extend the system bus to a slave microprocessor or to transfer data bytes to and from a floppy disk controller. PPI is a general purpose programmable I/O device designed to by interfacing with microprocessor · I/O Interface (Interrupt and DMA Mode). Direct memory access with DMA controller / Step After accepting the DMA service request from the DMAC, the CPU will send hold Interface with microprocessor for 1’s and 2’s complement of a number · Parallel .

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Embedded Systems Practice Tests.

Microprocessor DMA Controller

Port A can be used for bidirectional handshake data transfer. Only port A can be initialized in this mode. It is the low memory read signal, which is used to read the data from the addressed memory locations during DMA read cycles. Computer architecture Interview Questions.

Some of the pins of port C function as handshake lines. 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.

These are the active-low and high inactive DMA acknowledge lines, which updates the peripheral requesting device service about the status controllerr their request by the Clntroller.

In the master mode, the lines which are used to send higher byte of the generated address are sent to the latch.


Address lines Cnotroller 1 and A 0 allow to access a data register for each port or a control register, as listed below:. In the master mode, they are the four least significant memory address output lines generated by As an example, consider an input device connected to at port A.

Computer architecture Practice Tests. Top 10 facts why you need a cover letter? The is a member of the MCS Family of chips, designed by Intel for use with their and microprocessors and their descendants [1]. Jobs in Meghalaya Jobs in Shillong. This signal is used to convert the higher byte of the memory address generated by the DMA controller into the latches.

In the slave mode, it is connected with a DRQ input line Digital Communication Interview Questions. Digital Logic Design Practice Tests. Retrieved 3 June Each line of port C PC 7 – PC 0 can be set or reset by writing a suitable value to the dmz word register. The ‘s outputs are latched to hold the last data written to them.

Microprocessor 8257 DMA Controller Microprocessor

The two halves of port C can be either used together as an additional 8-bit port, or they can be used as individual 4-bit ports. In the Slave mode, it carries command words to and status word from Digital Logic Design Interview Questions. Report Attrition rate dips in corporate India: The mark will be activated after each cycles or integral multiples of it from the beginning. How to design your resume? It is an active-low chip select line.


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. These lines can also act as strobe lines for the requesting devices.

Microprocessor And Its Applications. For example, if port B and upper port C have to be initialized as input ports and lower port C and port A as output ports all in mode It is the low memory read signal, which is used to read the data from the addressed memory locations during DMA read cycles.

The inputs are not latched because the CPU only has to read their current dontroller, then store the data in a CPU register or memory if it needs to be referenced at a later time.

Direct Memory Access (DMA) Data Transfer

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 controllr slave mode, it is connected with a DRQ input line Making a great Resume: It is an active-low signal, i.

For port B in this mode irrespective of whether is acting as an input port or output portPC0, PC1 and PC2 pins function as handshake lines.