Demand Data-Transfer Mode With Autoinitialize Buffer-Transfer Mode - Intel 386 User Manual

DMA channel
relinquishes
No
bus control.
Figure 12-15. Demand Data-transfer Mode with Autoinitialize Buffer-transfer Mode
After initialization, the DMA channel is
programmed with the requester and target
addresses and a byte count.
DMA gains bus control.
DMA transfers one byte or word of data
and decrements the byte count.
Yes
DREQ n
active?
No
DMA channel relinquishes bus control.
DMA channel is reprogrammed with the
original addresses and byte count.
DMA CONTROLLER
No
DREQ n
active?
Yes
Byte
count = FFFFFFH
or EOP#
active?
Yes
A2339-02
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