IDA is the most powerful disassembler for Max OS 8 and Mac OS 9 PEF files.

The Motorola 68K family of processors is huge and very widely used. A few sample parts: MC68000, MC68010, MC68020, MC68030, MC68040, MC68330, MC68882, MC68851, MC68020EX, MC68302 Integrated Communication Processor, MC68306 68K/ColdFire, MC68331 68K/ColdFire, MC68332 68K/ColdFire, MC68336 68K/ColdFire, MC68340 68K/ColdFire, MC68360 Integrated Communication Processor, MC68F375 68K/ColdFire, MC68376 68K/ColdFire, etc.

Assembler code