Mikroelektronika MIKROE-742 데이터 시트

Data memory consists of : 

- Rx space 
- I/O Memory 
- Extended I/O Memory (MCU dependent) 
- Internal SRAM 

Rx space consists of 32 general purpose working 8-bit registers (R0-R31). These
registers have the shortest (fastest) access time, which allows single-cycle Arith-
metic Logic Unit (ALU) operation.
I/O Memory space contains addresses for CPU peripheral function, such as Control
registers, SPI, and other I/O functions. 
Due to the complexity, some AVR microcontrollers with more peripherals have
Extended I/O memory, which occupies part of the internal SRAM. Extended I/O
memory is MCU dependent. 
Storing data in I/O and Extended I/O memory is handled by the compiler only. Users
can not use this memory space for storing their data. 
Internal SRAM (Data Memory) is used for temporarily storing and keeping interme-
diate results and variables (static link and dynamic link). 

There are four memory type specifiers that can be used to refer to the data memo-

and 

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- SOFTWARE AND HARDWARE SOLUTIONS FOR EMBEDDED WORLD

CHAPTER 4