XR88C681_06 Datasheet, PDF (24/101 Pages) Exar Corporation – CMOS Dual Channel UART (DUART)

XR88C681
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.
Interrupt
Control
-INT1
-INT0
Timer 2 (8032/8052)
Timer 1
Timer 0
Serial Port
128 bytes
RAM
(8032/8052)
Other
Registers
128 bytes
RAM
ROM
0K - 8031/8032
4K - 8051
8K - 8052
Timer 2
(8032/8052)
Timer 1
Timer 0
-T2EX
-T2
-T1
-T0
CPU
Oscillator
Bus Control
I/O Ports
Serial Port
-EA
RST
ALE
-PSEN
P 0 P1 P2
P3
-RXD -TXD
Figure 3. Block Diagram of the 8051 Microcontroller
Rev. 2.11
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