P87C51RB2 PHILIPS [NXP Semiconductors], P87C51RB2 Datasheet - Page 50

• Manufacturer Part Number: P87C51RB2
• Description: 80C51 8-bit microcontroller family
• Manufacturer: PHILIPS [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
2003 Jan 24
PORT 0
PORT 2
80C51 8-bit microcontroller family
with 512B/1KB RAM, low voltage (2.7 to 5.5 V), low power, high
speed (30/33 MHz)
PSEN
ALE
RD
PORT 0
PORT 2
PSEN
ALE
t
AVLL
FROM RI OR DPL
A0–A7
t
LLAX
t
t
AVWL
LHLL
t
t
LLWL
AVLL
A0–A7
Figure 34. External Program Memory Read Cycle
8KB/16KB/32KB/64KB OTP
t
t
AVDV
P2.0–P2.7 OR A8–A15 FROM DPF
RLAZ
Figure 35. External Data Memory Read Cycle
t
LLDV
t
t
t
AVIV
LLAX
LLPL
t
LLIV
t
t
PLIV
RLDV
A0–A15
t
PLAZ
t
PLPH
t
RLRH
t
PXIX
INSTR IN
50
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
AVLL
WHLH
LLPL
P87C51RA2/RB2/RC2/RD2
= 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
SU00006
INSTR IN
Product data
SU00025