
50 EMBEDDED SYSTEMS
Now about the address bus: If the address bus (internal) is 16 bits as is the case of
8051, a maximum of 2
16
bytes, that is, 64K of internal memory, can be addressed by the
CPU. e memory, in this context, is ROM, where the code will fi nally reside. Besides
this, there is RAM available inside the chip. is is relatively small and is divided as
general purpose registers, R/W memory area and special function registers (SFRs). e
latter refers to the registers associated with the peripherals.
Corresponding to every peripheral, a number of registers are needed. As an example,
think of a timer. A timer unit allows the generation ...