fred@mot.UUCP (Fred Christiansen) (10/30/84)
[] Within Motorola, M68000 refers to the family of microprocessors, of which the MC68000, MC68010, and MC68020 are instances. Other M68000 suppliers, such as Mostek (e.g., MK68000), Signetics, Thomson-CSF, and Hitachi, have their own unique prefix. In our development of the SGS 68000 C compiler for UNIX System V/M68000 with AT&T Bell Labs, we sought an #ifdef predefine which would indicate the hardware family architecture (such as 'vax' for all vaxen, 'pdp11' for all pdp11's), and decided on 'm68k'. We specifically avoided an 'mc' prefix as that smacked of parochialism. We also avoided 'm68000' as that suggests specificity over generality. In the event that an #ifdef is needed for something very processor specific (handling stack faults, for instance), our practice has been to add an #ifdef (or extend an #if) with M68000, M68010, or M68020, making the definition (-D) in a makefile's compile line. The capital M is arbitrary but consistent with the mechanism we recommend for identifying the target processor (e.g., to a compiler, via an environment variable PROCESSOR, to enable specific code generation).