The Vax version of as accepts any of the following options, gives a warning message that the option was ignored and proceeds. These options are for compatibility with scripts designed for other people's assemblers.
These are obsolete options used to debug old assemblers.
This option expects a number following the -d. Like options that expect filenames, the number may immediately follow the -d (old standard) or constitute the whole of the command line argument that follows -d (gnu standard).
Some other assemblers use a temporary file. This option commanded them to keep the information in active memory rather than in a disk file. as always does this, so this option is redundant.
Many 32-bit computers permit a variety of branch instructions to do the same job. Some of these instructions are short (and fast) but have a limited range; others are long (and slow) but can branch anywhere in virtual memory. Often there are 3 flavors of branch: short, medium and long. Some other assemblers would emit short and medium branches, unless told by this option to emit short and long branches.
Some other assemblers may use a temporary file, and this option takes a filename being the directory to site the temporary file. Since as does not use a temporary disk file, this option makes no difference. -t needs exactly one filename.
The Vax version of the assembler accepts additional options when compiled for VMS:
External symbol or section (used for global variables) names are not case sensitive on VAX/VMS and always mapped to upper case. This is contrary to the C language definition which explicitly distinguishes upper and lower case. To implement a standard conforming C compiler, names must be changed (mapped) to preserve the case information. The default mapping is to convert all lower case characters to uppercase and adding an underscore followed by a 6 digit hex value, representing a 24 digit binary value. The one digits in the binary value represent which characters are uppercase in the original symbol name.
The -h n option determines how we map names. This takes several values. No -h switch at all allows case hacking as described above. A value of zero (-h0) implies names should be upper case, and inhibits the case hack. A value of 2 (-h2) implies names should be all lower case, with no case hack. A value of 3 (-h3) implies that case should be preserved. The value 1 is unused. The -H option directs as to display every mapped symbol during assembly.
Symbols whose names include a dollar sign $ are exceptions to the general name mapping. These symbols are normally only used to reference VMS library names. Such symbols are always mapped to upper case.
The -+ option causes as to truncate any symbol name larger than 31 characters. The -+ option also prevents some code following the _main symbol normally added to make the object file compatible with Vax-11 "C".
This option is ignored for backward compatibility with as version 1.x.
The -H option causes as to print every symbol which was changed by case mapping.