Philips Semiconductors
Product specification
Single-chip 8-bit microcontroller
80C552/83C552
EXPLANATION OF THE AC SYMBOLS
Each timing symbol has five characters. The
first character is always ‘t’ (= time). The other
characters, depending on their positions,
indicate the name of a signal or the logical
status of that signal. The designations are:
A – Address
Q – Output data
R – RD signal
– Time
V – Valid
W – WR signal
t
X – No longer a valid logic level
Z – Float
C – Clock
D – Input data
H – Logic level high
Examples: t
= Time for address valid to
ALE low.
AVLL
I
– Instruction (program memory contents)
t
= Time for ALE low to
PSEN low.
LLPL
L – Logic level low, or ALE
P – PSEN
t
LHLL
ALE
t
PLPH
t
t
LLPL
AVLL
t
LLIV
PSEN
t
PLIV
t
PXIZ
t
t
PLAZ
LLAX
t
PXIX
A0–A7
INSTR IN
A0–A7
PORT 0
PORT 2
t
AVIV
A8–A15
A8–A15
Figure 2. External Program Memory Read Cycle
ALE
PSEN
RD
t
WHLH
t
LLDV
t
t
LLWL
RLRH
t
RHDZ
t
LLAX
t
t
RLDV
AVLL
t
t
RLAZ
RHDX
A0–A7
FROM RI OR DPL
PORT 0
PORT 2
DATA IN
A0–A7 FROM PCL
INSTR IN
t
AVWL
t
AVDV
P2.0–P2.7 OR A8–A15 FROM DPH
A8–A15 FROM PCH
Figure 3. External Data Memory Read Cycle
16
1998 Aug 13
NXP [ NXP ]
