xr88c681 Exar Corporation, xr88c681 Datasheet - Page 31

• Manufacturer Part Number: xr88c681
• Description: Cmos Dual Channel Uart Duart
• Manufacturer: Exar Corporation

Figure 8 presents a schematic of the 8085 CPU Module.
Figure 9 illustrates an approach to interfacing the
XR88C681 DUART to the 8085 CPU module. Note that
the XR88C681 DUART, in this case, is memory mapped
(e.g., the signals -MEMR and -MEMW of the CPU module
are connected to the -RD and -WR pins of the DUART).
Rev. 2.11
X1
X2
TRAP
RST 7.5
RST 6.5
RST 5.5
INTR
-
INTA
8085 CPU
-
ALE
IO/M
AD5
AD7
-
AD0
AD1
AD2
AD3
AD4
AD6
A8
A9
A10
A11
A12
A13
A14
A15
-
WR
RD
Figure 8. A Schematic of the 8085 CPU Module
1D
2D
3D
4D
5D
6D
7D
8D
C
31
74LS373
However, the user could have just as easily connected the
XR88C681 device to the CPU module’s I/O port (e.g, the
signal -IOR and -IOW of the CPU module are connected
to the -RD and -WR pins of the DUART, respectively).
A13
A8
A9
A10
A11
A12
A14
A15
1Q
2Q
3Q
4Q
5Q
6Q
7Q
8Q
D6
D0
D1
D2
D3
D5
D7
A1
A2
A3
A4
A5
D4
A0
A6
A7
XR88C681
-
-
-
-
IOR
MEMR
IOW
MEMW