
27
4109LS–8051–02/08
AT8xC51SND1C
7.3.2.3
Waveforms
Figure 7-10. External Data 8-bit Bus Cycle - Read Waveforms
Figure 7-11. External Data 8-bit Bus Cycle - Write Waveforms
7.3.3
External IDE 16-bit Bus Cycles
7.3.3.1
Definition of Symbols
Table 29. External IDE 16-bit Bus Cycles Timing Symbol Definitions
T
AVDV
T
LLAX
T
RHDX
T
RHDZ
T
AVLL
T
AVRL
P2
P0
RD
ALE
T
LHLL
T
RLRH
Data In
A15:8
T
RLAZ
T
LLRL
T
RHLH
T
RLDV
D7:0
A7:0
T
WHLH
TAVWL
T
LLAX
T
WHQX
P2
P0
WR
ALE
TLHLL
T
WLWH
A15:8
TAVLL
T
QVWH
D7:0
Data Out
T
LLWL
A7:0
Signals
Conditions
A
Address
H
High
D
Data In
L
Low
L
ALE
V
Valid
Q
Data Out
X
No Longer Valid
R
RD
Z
Floating
W
WR