xr88c681 Exar Corporation, xr88c681 Datasheet - Page 24

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

C.6.1.1 8051 Microcontroller
The 8051 family of microcontrollers is manufactured by Intel and comes with a variety of amenities. Some of these
amenities include:
D On chip serial port
D Four 8 bit I/O port (P0 - P3)
D Two 16 bit timers
D 4k bytes of ROM
D 128 bytes of RAM
Figure 3 presents a block diagram of the 8051 microcontroller, and Figure 4 presents the pin out of this device.
Rev. 2.11
Oscillator
Interrupt
Control
CPU
RST
-EA
-INT1
-INT0
Timer 2 (8032/8052)
Timer 1
Timer 0
Serial Port
Figure 3. Block Diagram of the 8051 Microcontroller
Registers
Other
Bus Control
(8032/8052)
128 bytes
-PSEN
ALE
128 bytes
RAM
RAM
P 0
24
P1
I/O Ports
0K - 8031/8032
4K - 8051
8K - 8052
P2
ROM
P3
(8032/8052)
-RXD
Timer 1
Timer 0
Timer 2
Serial Port
-TXD
-T2EX
-T2
-T1
-T0