P89C538 データシートの表示（PDF） - Philips Electronics

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P89C538

CMOS single-chip 8-bit microcontrollers with FLASH program memory

Philips Electronics 

Philips Semiconductors

CMOS single-chip 8-bit microcontrollers

with FLASH program memory

Preliminary specification

89C535/89C536/89C538

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

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: tAVLL = Time for address valid to ALE low.

tLLPL =Time for ALE low to PSEN low.

ALE

PSEN

PORT 0

PORT 2

tLHLL

tAVLL

tLLPL

tPLPH

tLLIV

tPLIV

tLLAX

tPLAZ

tPXIX

A0–A7

INSTR IN

tPXIZ

tAVIV

A0–A15

A0–A7

A8–A15

ALE

PSEN

RD

PORT 0

PORT 2

Figure 9. External Program Memory Read Cycle

tWHLH

tLLDV

tLLWL

tRLRH

tAVLL

tLLAX

A0–A7

FROM RI OR DPL

tRLAZ

tRLDV

tRHDX

DATA IN

tAVWL

tAVDV

P2.0–P2.7 OR A8–A15 FROM DPF

tRHDZ

A0–A7 FROM PCL

A0–A15 FROM PCH

1997 Jun 05

Figure 10. External Data Memory Read Cycle

19

SU00006

INSTR IN

SU00025

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