XR16C850 Datasheet, PDF (5/55 Pages) Exar Corporation – UART with 128-byte FIFO’s FIFO Counters and Half-duplex Control

XR16C850
SYMBOL DESCRIPTION
Symbol
A0
A1
A2
A3 / IOR
A4
A5 / CS0
A6 / CS1
A7 / -CS2
Pin
Signal
40 44 48 52 type
Pin Description
28 31 28 31
I
Address-0 Select Bit - Internal registers address
selection in PC and STD modes.
27 30 27 30
I
Address-1 Select Bit Internal registers address
selection in PC and STD modes
26 29 26 29
I
Address-2 Select Bit Internal registers address
selection in PC and STD modes
22 25 20 22
I
Address-3 Select Bit or Input/Output Read (dual
function) - When the PC mode is selected, this pin
is used as 4th address line to decode the COM1-4
and LPT ports. During STD mode operation this pin
is used as Read strobe. Its function is the same as
-IOR (see -IOR), except it is active high. Either an
active -IOR or IOR is required to transfer data from
850 to CPU during a read operation. Connect this
pin to GND when –IOR is used.
-
12
6
6
I
Address-4 Select Bit (internal pull-up) - When the
PC mode is selected, this pin is used as 5th address
line to decode the COM1-4 and LPT ports. This pin
has no function in the STD mode.
12 14
9
9
I
Address-5 Select Bit or Chip Select-0 (dual function)
- When the PC mode is selected, this pin is used as
6th address line to decode the COM1-4 and LPT
ports. During STD mode a logical 1 on this pin
provides the chip select 0 function. Connect this pin
to VCC when CS1 or –CS2 is used.
13 15 10 10
I
Address-6 Select Bit or Chip Select-1 (dual function)
- When the PC mode is selected, this pin is used as
7th address line to decode the COM1-4 and LPT
ports. During STD mode a logical 1 on this pin
provides the chip select 1 function. Connect this pin
to VCC when CS0 or –CS2 is used.
14 16 11
7
I
Address-7 Select Bit or Chip Select -2 (dual func-
tion) - When the PC mode is selected, this pin is
used as 8th address line to decode the COM1-4 and
LPT ports. During STD mode a logical 1 on this pin
provides the chip select 2 function. Connect this pin
Rev. 1.20
5