Intel 386 - Manual (Page 358)

12-23
DMA CONTROLLER
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.
DMA channel is reprogrammed with the
original addresses and byte count.
A2339-02
Yes
No
DREQ n
active?
Yes
No
DMA channel
relinquishes
bus control.
DREQ n
active?
Yes
No
Byte
count = FFFFFFH
or EOP#
active?
DMA channel relinquishes bus control.