All numbers may be entered as positive or negative values --
most instructions and directives allow both as parameters.
Some (such as ADDQ) require the number to be in a specific
range. The assembler checks in these cases to make sure the
resulting value lies in the appropriate range.

The following describes a number of values which can
be used within any mathematical expression:

Decimal Number: A decimal number is specified by simply
entering a base-10 number without a prefix.

Examples: 91, -45

Hexadecimal Number: A hexadecimal number is specified
by a base-16 number preceded by a dollar sign ($).

Examples: $81, -$FFE3

Binary Number: A binary number is specified by a base-2
number preceded by a percent sign (%).

Examples: %1010, -%11111111

Character: A character or character sequence is specified
by a one- to four-character seqence enclosed in single

Examples: 'a', 'AbCd', 'CODE'

Symbol Name: A symbol name consists of a sequence of
letters, numbers, and underscores and begins with
a letter or an underscore. Symbols must be declared
before they are used in an expression. Strings which
are predefined directives or instructions may not be
used for variable names.