Zilog Z08470 - Manual (Page 152)

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7UGT /CPWCN
UM008101-0601 Direct Memory Access
Figure 50. CE/WAIT Multiplexer
Figure 51. Simultaneous Transfer Multiplexer
I1 I0
SEL 1/4
74LS157
Y
DMA
CE/WAIT
BUSACK
CE (From Decoder)
WAIT (From Peripheral or Memory Logic)
+5V
IOWR IORD MWR MRD
BUSACK or BAI-BAO
RD (from DMA)
IORQ (from DMA)
Y4 Y3 Y1
SEL 74LS257 OE
Y2
0 1 0 0 0 1 1 1