Small Model

In this model, all variables, by default, reside in the internal data memory of the 8051 system—as if they were declared explicitly using the data memory type specifier.

In this memory model, variable access is very efficient. However, all objects (that are not explicitly located in another memory area) and the stack must fit into the internal RAM. Stack size is critical because the stack space used depends on the nesting depth of the various functions.

Typically, if the linker is configured to overlay variables in the internal data memory, the small memory model is the best model to use.