Specifications

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Symbol file syntax
The symbol file is a plain text file that may be created/modified with any text
editor. The file contains lines that fall into one of three categories:
❏ comment lines;
❏ command lines;
❏ blank lines.
Comment lines are denoted by ';' as the first non-whitespace character on the line.
Command lines start with one of the specified keywords. Parameters follow the
command keyword, separated by spaces or tabs. A comment may be added to the
end of a command, preceded by the ';' character. Blank lines are ignored.
Number value parameters may be given in decimal (the default), octal or hex using
standard C language conventions (e.g. 0x prefix for hex).
The symbol file command syntax contains an include directive which allows one
symbol file to be included within another. Included files may be nested to any
practical depth. A particular use of this feature is to have a symbol file containing
a generic set of defintions for a processor or item of hardware. This can then be
included within a symbol file with additional definitions for a specific software
image that runs on that processor/hardware. The pair of example files,
gameboy.sym
and
tetris.sym
, shows this in action with generic GameBoy
definitions in one file and specific defintions for a tetris game cartidge in the other.
Valid command keywords and their meaning are summarised in the table below.