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Extended 8051 Devices

The extended 8051 architecture includes the following memory classes.

BIT, DATA, and IDATA

The BIT, DATA, and IDATA memory classes comprise the on-chip memory of the extended 8051 architecture and are shown in the following figure.

On-chip Data Memory

CODE, CONST, and HCONST

HCONSTMemory

The HCONST memory class is available only on those devices or target systems with far memory support.

The HCONST memory class includes the CODE memory class (which is still limited to 64 KBytes) and up to 64 code banks that may be used for code banking applications.

In addition, far const variables are stored in this memory class.

XDATA, PDATA, and HDATA

HDATA Memory

The HDATA memory class is available only on those devices or target systems with far memory support.

The HDATA memory class includes the XDATA memory class (which is still limited to 64 KBytes) and up to 8 MBytes of far variables.

The PDATA memory class is a 256-byte page within the XDATA memory class.

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