XR88C681J View Datasheet(PDF) - Exar Corporation

Part Name

Description

MFG CO.

XR88C681J

CMOS Dual Channel UART (DUART)

Exar Corporation 

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XR88C681

RST 6.5

AD0 - AD7

ALE

A15 - A8

-IO/M

-RD

-WR

8085 CPU

Vcc

D

Q

C

74LS373

A7 - A4

Address Decoding

Logic

-IOR

-MEMR

-IOW

-MEMW

-INTR

D0 - D7

A0 - A3

-CS

-RD

-WR

XR88C681

Figure 10. The XR88C681/8085 CPU Interface for Direct Interrupt Processing

(Interrupt Service Routine is located at 003416 in System Memory)

Figure 11 presents a schematic where the DUART will request a “External-Vectored” Interrupt to the 8085 CPU. In this

case, the Interrupt Service Routine for the DUART must begin at 002016 in system memory.

Rev. 2.11

34

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