COMPACT

Abbreviation

CP

Arguments

None.

Default

SMALL

Description

This directive controls the selection of the memory model to be implemented.
In the COMPACT memory model, all variables and local data segments of functions and procedures are defined to reside in the external data memory of the 8051 system. This external data memory may be up to 256 bytes (one page) long. With this model the short form of addressing the external data memory through @R0/R1 is used.
Regardless of memory model, variables may be declared to be in any of the 8051 memory ranges. However, place frequently used variables (such as loop counters and array indices) in internal data memory. This significantly improves system performance.