Intel 386 - Manual (Page 354)

12-19
DMA CONTROLLER
Figure 12-11. Block Data-transfer Mode with Single Buffer-transfer Mode
A2334-02
Buffer transfer is complete, so channel
becomes idle.
DREQ n
active?
Yes
No
Yes
No
Byte
count = FFFFFFH
or EOP#
active?
DMA channel relinquishes bus control.
DMA transfers one byte or word of data and
decrements the byte count.
DMA gains bus control.
After initialization, the DMA channel is
programmed with the requester and target
addresses and a byte count.