The simplest model interface is the Basic model. This provides a mechanism for calling a user-supplied function during initialization (see Basic model initialization function). The function can then install upcalls, for example, to add functionality.

Basic models can be initialized either before or after memory models are initialized. This means that there are two distinct types of basic model:

Whether a basic model is early or late is controlled by the location of its configuration in the ARMulator configuration file. See Application Note 52, The ARMulator Configuration File (ARM DAI 0052) for more information.