Intel 80C186XL, 80C188XL user manual Generating a DMA Acknowledge, Dma Unit Examples

Models: 80C186XL 80C188XL

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10.3.4 Generating a DMA Acknowledge

DIRECT MEMORY ACCESS UNIT

10.3.4 Generating a DMA Acknowledge

The DMA channels do not provide a distinct DMA acknowledge signal. A chip-select line can be programmed to activate for the memory or I/O range that requires the acknowledge. The chip- select must be programmed to activate only when a DMA is in progress. Latched status line S6 can be used as a qualifier to the chip-select for situations in which the chip-select line will be ac- tive for both DMA and normal data accesses.

10.4 DMA UNIT EXAMPLES

Example 10-1 sets up channel 0 to perform an unsynchronized burst transfer from memory to memory while channel 1 is used to service an external DMA request from a hard disk controller.

Example 10-2 shows timed DMA transfers. A sawtooth waveform is created using DMA trans- fers to an A/D converter.

10-22

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Intel 80C186XL, 80C188XL user manual Generating a DMA Acknowledge, Dma Unit Examples