z80asm - assembler for the Z80 microprocessor
z80asm [options] [files...]
Z80asm is an assembler for Z80 assembly. If no input files are
specified, stdin is used. If no output file is specified, "a.bin" is
used. If "-" is specified as output file, stdout is used. This makes
it possible to use the assembler in a pipeline.
When multiple input files are specified, the assembler first uses all
files which were specified with -i or --input, in the order given.
After that, all files which were specified as non-option arguments are
assembled, also in the order given.
Show summary of options and exit.
Display version information and exit.
Be verbose. Specify multiple times to be more verbose.
Messages are sent to standard error.
Write a list file. No filename or '-' means stderr.
Write a label file. No filename or '-' means stderr.
prefix all labels with this prefix.
Specify an input file (-i may be omitted). '-' means stdin.
Specify the output file. '-' or completely omitting the option
Add a directory to the include path. The order in which the
directories are tried is from back to front: the last directory
specified has the highest priority. "/usr/share/z80asm" is
always in the include path (with lowest priority), you don't
have to specify it.
Produce output even in case of errors. Normally the output,
list and label files are removed when assembly is unsuccesful.
All mnemonics and registers are case insensitive. All other text (in
particular, labels and macros) are not. Undocumented opcodes are as
much as possible supported:
sll and sli are equal and can both be used.
ixh, ixl, iyh and iyl can be used.
Assembler directives are:
Include a binary file into the resulting assembled file. This
can be used to include text files, or images, sound files, etc.
The filename is searched for in the current directory, and then
in the include path, just like for include. Also like for
include, the quotes can be any character (but must match) and no
substitution is performed (so ~ is not your home directory).
defb or db arg, arg, arg, ...
defm or dm "String", 'String'
Define message. Each character in the string is stored as one
byte. Backslash escapes are allowed, as in characters in
expressions. Unlike the argument for include, the quotes must
really be quotes (but they can be single or double quotes. The
closing quote must match the opening quote.)
defb/db and defm/dm are really aliases; either can take both quoted
strings and numbers:
defb "This text should be in a buffer
defs or ds count [, value]
Define space. count bytes are reserved. Each of them is
initialised to the specified value, or 0 if no value is
defw or dw arg, arg, arg, ...
Define words. Each argument is stored as two bytes, the low
order byte first.
end End assembly of this source file. Any remaining lines are
copied into the list file (if present), but not assembled.
label: equ expression
Define label to have value expression.
code block 1
code block 2
code block 3
code block n
Conditionally assemble code. If expression is not 0, all odd
code blocks are assembled, if expression is 0, all even blocks
are assembled. Usually only one or two code blocks are present.
Include file into the source. The quotes around the file for
include are mandatory, but you can choose the quotes yourself.
eg, you may use % or even a letter as a quote. The filename
does not undergo any expansion, so \, ~, $, etc are passed as
written (which means ~ will not be your home directory.) The
filename is used as specified, and then prefixed with each
directory in the include path, until it can be opened.
label: macro arg1, arg2, ...
Define a macro. The macro can be used where an opcode is
expected. The code block is then substituted, with the given
values for the arguments. This is a textual substitution, so
the following example is valid:
This will generate a label with a constructed name (it's not a
very useful example, but it shows the possiblities).
Set the "program counter" to address. This does not add any
bytes to the resulting binary, it only determines how the rest
of the code is interpreted (in particular, the value of labels
Seek to position offset in the output file. This can be used
for overwiting previously assembled code, for example for
patching a binary which was included using incbin.
All expressions can use the following operators, in order of
precedence: (a, b and c denote subexpressions)
a ? b : c
If a is not zero, return b, otherwise c
a | b bitwise or
a ^ b bitwise xor
a & b bitwise and
a == b, a = b, a != b
a <= b, a >= b, a < b, a > b
a << b, a >> b
a + b, a - b
addition and subtraction
a * b, a / b, a % b
multiplication, division and modulo
~a, +a, -a
bitwise not, no effect and negation
?label 1 if label exists, 0 if it does not. This does not generate an
error if label does not exist. Note that this is usually
evaluated immediately (if the rest of the expression permits),
and it does not check if the label is defined later. This means
it can be used as the argument of if , to get the functionality
of #ifdef in C.
Literals in expressions may be written as: (case does not matter)
@c11 arbitrary base number (specified by 'c' so c+1 == 10: here base
14, 14d, @914
016, 16o, 16q, &o16, @716
0Eh, 0xE, &hE, $E, @FE
hexadecimal number (for the first notations, the first character
must be 0-9)
%1110, 1110b, &b1110, @11110
's' ASCII code of 's'
', '\a', ' '
Newline, carriage return, alert, tab
nn' Octal ASCII code
$ address of first byte of current command
In all expressions, labels may be used. However, there are some
expressions where the value must be computable at once, and therefore
only previously defined labels may be used. This is the case for:
- The argument of org
- The argument of seek
- The argument of equ (eg, a label definition)
- The first argument of ds
- The argument of if
In all other expressions, labels which are defined later may be used.
Labels must consist of letters, digits, underscores and periods, and
must not start with a digit. Labels are case sensitive.
Labels starting with a period (.) are local , which means their scope
is only the current include file or macro definition (and files
included/macros called from it). This is particularly useful for
macros, to prevent duplicate definitions when using a macro more than
If assembly was successful, no output is produced (except the result,
and messages triggered by --verbose) and 0 is returned. At any error,
there is output on the standard error and 1 is returned.
Parts that are not assembled because of an if statement and macros
which are defined but never used are only checked to have a correct
command. The argument is not parsed. This means that if the file
passes through the assembler with no warnings or errors, it may still
not assemble correctly in a different setting (where the if's give
If you find a bug, or want to send comments, please use the web
interface at http://savannah.nongnu.org/projects/z80asm/ or send an
e-mail to firstname.lastname@example.org.
Z80asm was written by Bas Wijnen <email@example.com>. Some patches
were provided by Jan Wilmans <firstname.lastname@example.org>
May 10, 2005 Z80ASM(1)