Z80 Datasheet, PDF (152/330 Pages) Zilog, Inc. – Z80 CPU PERIPHERALS

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7UGT /CPWCN

WAIT (From Peripheral or Memory Logic)
CE (From Decoder)
BUSACK
I1
I0
SEL ^1/4
74LS157
Y
CE/WAIT
DMA
Figure 50. CE/WAIT Multiplexer
+5V
BUSACK or BAI-BAO
RD (from DMA)
IORQ (from DMA)
0 10 101 01
SEL 74LS257 OE
Y4 Y3 Y2 Y1
IOWR IORD MWR MRD
Figure 51. Simultaneous Transfer Multiplexer
UM008101-0601
Direct Memory Access