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The idata memory type may be used to declare variables only. You may not declare idata functions. This memory is indirectly accessed using 8-bit addresses and is the on-chip RAM of the 8051. The amount of idata is limited in size (to 256 bytes or less). The lower addresses of idata overlap the corresponding addresses of data memory.

Variables declared idata are located in the IDATA memory class.

Declare idata variables as follows:

unsigned char idata variable;
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