# Special Function Register (SFR)
Controlling the peripherals by SFR (I/O memory) - interfaces between internal & external periperals
Microcontrollers tasks need to:
- Controll internal periperals
- timers, communication ports, … -Controll external peripherals - connected to the device
- sensors, displays, …
IO address space is made available as memory-mapped IO
- it is like data space (can be written / read)