N80C251SQ データシートの表示（PDF） - Intel

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N80C251SQ

HIGH-PERFORMANCE CHMOS MICROCONTROLLER

Intel 

8XC251SA/SB/SP/SQ HIGH-PERFORMANCE CHMOS MICROCONTROLLER

Table 7. Memory Signal Selections (RD1:0)

RD1:0

P1.7/CEX/

A17/WCLK

0 0 A17

0 1 P1.7/CEX4/

WCLK

1 0 P1.7/CEX4/

WCLK

1 1 P1.7/CEX4/

WCLK

P3.7/RD#/A16

PSEN#

WR#

Features

A16

A16

P3.7 only

RD# asserted

for addresses

≤ 7F:FFFFH

Asserted for

all addresses

Asserted for

all addresses

Asserted for

all addresses

Asserted for

≥ 80:0000H

Asserted for writes to

all memory locations

Asserted for writes to

all memory locations

Asserted for writes to

all memory locations

Asserted only for

writes to MCS 51

microcontroller data

memory locations.

256-Kbyte external

memory

128-Kbyte external

memory

64-Kbyte external

memory. One

additional port pin.

64-Kbyte external

memory. Compatible

with MCS 51 micro-

controllers.

PRELIMINARY

13

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