Master listing of CPP symbols

[Guy Harris]

> Therefor I am collecting a list of what #defines are used so that I can
> use the same ones as everyone else;
> 	-- you all DO use the same ones -don't you ?
> 
> 			Hardware
> #define		Machine
> vax		vax m/c
> pdp11		pdp11's
> mc68000		68000 CPUs	I gather that some people use m68000, how
> 				widespread is this ? Can we agree on one or
> 				the other as a standard.

Unfortunately, AT&T throws in a joker; there are now 3 competing names,
"mc68000", "m68000", and "m68k".  Arguably, either "m68000" (which we, and
I think some other people, use) or "m68k" should be used for all machines based
on 68000 family CPU chips (68000, 68010, 68020) and "mc68000" used specifically
to imply that it's an MC68000 chip.  Precedent exists for this sort of thing;
"u3b" implies a 3B, "u3b5" implies a 3B5.

> It has been suggested that some of the above have specific values (other
> than 1). Thus on a pdp11/44, pdp11 would have a value of 44. Thus in the few
> places where the actual cpu mattered (eg I/O, memory management), appropriate
> compile tests could be made.

This could get tricky, as not all "model numbers" are numeric, and CPP can
only do "#if"s on numeric values.

> Would it be useful (possible) to have defines for different memory management
> architectures ?

What specific architectures?  Paged vs. non-paged, or specific hardware?
The former is nice; precedent sort of exists for this in the VMUNIX define
used in some Berkeley software, except there's some software out there that
thinks "VMUNIX" means "Berkeley UNIX", which it shouldn't.  The latter is
probably not useful, as the only software that will depend on it are parts
of the OS, and #ifdefing that probably doesn't add anything (if you have to
rewrite 1000 lines of code for a particular MMU - or for any other configuration
change - it's probably best done by linking in different modules for different
configurations).

> 			Software
> I have got an implies section here. The idea is that one piece of software
> looks sufficiently like another, so rather than going round adding the #define
> when a new release come along, we only need change the places where there is
> a difference. Thus SYS5 implies SYS3, as most of System 5 looks like System 3.
> Maybe there should be a USG implying SYS3 (but not SYS5).
> 
> #define:	O/S		Implies -ie also defined:
> SYS8		System 8	SYS3	(SYS5 as well ?) - or is it SYS5R3?

What is System 8?  It looks like Bell has reset their numbering scheme yet
again, with every UNIX until 2^31-1 seconds after January 1, 1970, 0 hours
GMT, being called System V.

	Guy Harris
	{seismo,ihnp4,allegra}!rlgvax!guy