XR16C850 Datasheet, PDF (14/55 Pages) Exar Corporation – UART with 128-byte FIFO’s FIFO Counters and Half-duplex Control

XR16C850
FUNCTIONAL DESCRIPTIONS
Interface Options
Standard 16550 Mode Interface
The 850 provides a pin compatible interface for emula-
tion of the 16C550 when in the STD mode. The STD
mode is selected by making the SEL pin a logic 1
(VCC). When the SEL pin is set to a logic 1, the 850
interface is the same as Industry Standard 16C550.
Figure 4 shows a typical connection to the PC ISA bus.
D0
D1
D2
D3
D4
D5
D6
D7
A0
A1
A2
IOR*
IOW*
A3
A4
A5
A6
A7
A8
A9
AEN*
IRQ3
IRQ4
RESET
J1
3F8
1
2
2F8
3
4
3E8
5
6
2E8
7
8
HDR2X4
J2
1
2
3
4
HDR2X2
3
2
U2A
74LS125A
VCC
D0
D1
D2
D3
D4
D5
D6
D7
A0
A1
A2
-IOR
-IOW
RCLK
-BAUDOUT
CS0
-CS2
CS1
SEL
-OP2
INT
RESET
IOW
IOR
-AS
Figure 4, STANDARD MODE INTERFACE
Rev. 1.20
14