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Full Address Mode (Block Transfer Mode): Figure 8-22 shows a transfer example in which
TEND output is enabled and word-size full address mode transfer (block transfer mode) is
performed from internal 16-bit, 1-state access space to external 16-bit, 2-state access space.
ø
Address bus
RD
HWR
LWR
TEND
Bus release
Figure 8-22 Example of Full Address Mode (Block Transfer Mode) Transfer
A one-block transfer is performed for one transfer request, and after the transfer the bus is
released. While the bus is released, one or more bus cycles are inserted by the CPU or DTC.
In the transfer end cycle of each block (the cycle in which the transfer counter reaches 0), a one-
state DMA dead cycle is inserted after the DMA write cycle.
One block is transmitted without interruption. NMI generation does not affect block transfer
operation.
DMA
DMA
DMA
read
write
read
Block transfer
DMA
DMA
DMA
write
dead
read
Bus release
DMA
DMA
DMA
write
read
write
Last block transfer
DMA
dead
Bus
release
271
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