Figure 94. operation mode transition – Zilog Z80180 User Manual
Page 300
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Z8018x
Family MPU User Manual
284
UM005003-0703
Figure 94. Operation Mode Transition
* 1. NORMAL: CPU executes instructions normally in NORMAL mode.
* 2. DMA request: DMA is requested in the following cases.
–
DREQ0, DREQ1 = 0
memory to/from (memory mapped) I/0 DMA transfer
–
b. DEO = 1 (memory to/from memory DMA transfer)
* 3. DMA end: DMA ends in the following cases:
DMA
NORMAL *1
RESET
REFRESH
BUS
RELEASE
BU
SR
EQ
=
0
BU
SR
EQ
=
1
B
U
SR
E
Q
=
0
B
U
SR
E
Q
=
1
RESET = 0
RES
ET =
0
RES
ET
= 1
R
E
SE
T
=
0
RES
ET
= 0
DMA
Requ
est *2
End o
f DM
A *3
R
E
FR
E
SH
R
eq
ue
st
E
nd
o
f R
E
FR
E
SH
E
nd
o
f R
E
FR
E
SH
R
E
FR
ES
H
R
eq
ue
st
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