M68K Architecture Documentation


DISCLAIMER: This documentation is derived from the cgen cpu description of this architecture, and does not represent official documentation of the chip maker.


In cgen-parlance, an architecture consists of machines and models. A `machine' is the specification of a variant of the architecture, and a `model' is the implementation of that specification. Typically there is a one-to-one correspondance between machine and model. The distinction allows for separation of what application programs see (the machine), and how to tune for the chip (what the compiler sees).
A "cpu family" is a cgen concoction to help organize the generated code. Chip variants that are quite dissimilar can be treated separately by the generated code even though they're both members of the same architecture.

M68K Architecture

This section describes various things about the cgen description of the M68K architecture. Familiarity with cgen cpu descriptions is assumed.

Bit number orientation (arch.lsb0?): lsb = 0

ISA description

CPU Families

Machine variants

m68k16 - Motorola M68000 (16-bit bus)

Model variants

mc68000 - Motorola MC68000 microprocessor

Registers

h-ar - address registers