Hardware manual

Common Features Description
2-18 Atmel 8051 Microcontrollers Hardware Manual
4316A–8051–01/04
Figure 2-1. 8051 Architecture Block Diagram
Note: (*)For Timer 2 only.
Figure 2-1 shows a functional block diagram of the 80C51s.
2.2 Special Function
Registers
A map of the on-chip memory area called SFR (Special Function Register) space is
shown in Figure 2-1. SFRs marked by parentheses are resident in the microcontroller
which have the Timer2 feature.Note that not all of the addresses are occupied. Read
accesses to these addresses will in general return random data.