xr88c681 Exar Corporation, xr88c681 Datasheet - Page 2

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

Rev. 2.11
D0 - D7
Buffer
Data
Bus
TXDA
Status Register
TSR
THR
Mode Registers
Channel A
A0 - A3
RXDA
RSR
RHR
Command Decoder
Operation Control
Address Decoder
-RD -WR -CS RESET
CRA
Figure 1. Block Diagram of the XR88C681
CRB
TSR
TXDB
THR
Mode Registers
Status Register
Channel B
RXDB
RHR
RSR
Internal Data Bus
IEI IEO -IACK -INTR
Interrupt Control
MISR
IMR
2
IVR
ISR
State Detectors
Change of
Input Port
IP0 - IP6
IPR
IPCR
ACR
CSRA
Counter/Timer
X1/CLK
Generator
Oscillator
Bit Rate
Timing
Function Select
Output Port
X2
Output Port
OP0 - OP7
CSRB
OPCR
OPR
Logic