p87c453ebaa NXP Semiconductors, p87c453ebaa Datasheet - Page 17

• Manufacturer Part Number: p87c453ebaa
• Description: 80c51 8-bit Microcontroller Family 8k/256 Otp/rom, Expanded I/o
• Manufacturer: NXP Semiconductors

Philips Semiconductors
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
C – Clock
D – Input data
H – Logic level high
I – Instruction (program memory contents)
L – Logic level low, or ALE
1998 Apr 23
PORT 0
PORT 2
80C51 8-bit microcontroller family
8K/256 OTP/ROM, expanded I/O
PSEN
ALE
RD
PORT 0
PORT 2
PSEN
ALE
t
AVLL
FROM RI OR DPL
A0–A7
t
LLAX
t
AVWL
t
LHLL
t
t
LLWL
AVLL
A0–A7
t
Figure 9. External Program Memory Read Cycle
t
P2.0–P2.7 OR A8–A15 FROM DPH
AVDV
RLAZ
Figure 10. External Data Memory Read Cycle
t
LLDV
t
t
AVIV
LLPL
t
LLAX
t
LLIV
t
RLDV
A0–A15
t
PLAZ
t
PLPH
t
RLRH
t
t
PLIV
PXIX
INSTR IN
17
t
RHDX
DATA IN
P – PSEN
Q – Output data
R – RD signal
t – Time
V – Valid
W – WR signal
X – No longer a valid logic level
Z – Float
Examples: t
t
PXIZ
t
RHDZ
t
t
WHLH
AVLL
LLPL
= Time for address valid to ALE low.
= Time for ALE low to PSEN low.
A0–A7
A0–A7 FROM PCL
A0–A15 FROM PCH
A8–A15
83C453/87C453
Preliminary specification
SU00056
INSTR IN
SU00007