doc.txt

.Overview of zmac
zmac is a Z-80 macro cross-assembler. It has all the features you'd
expect. It assembles the specified input file (with a '.z' extension
if there is no pre-existing extension and the file as given doesn't
exist) and produces program output in many different formats@format.
It also produces a nicely-formatted
listing of the machine code and cycle counts alongside the source
in a ".lst" file.

To reduce clutter and command line option usage, by default all zmac output is put
into an (auto-created) _zout_ subdirectory.  For _file.z_ the listing
will be in _zout/file.lst_, the TRS-80 executable format in _zout/file.cmd_
and so on.  For more friendly usage in make files and integrated development
environments the _-o_, _--oo_, _--xo_ and _--xd_ options may be used to select
sepcific output file formats and where they are written.

Undocumented@undoc Z-80 instructions are supported as well as 8080 code.

zmac strives to be a powerful assembler with expressions familiar to C
programmers while providing good backward compatibility with original
assemblers such as Edtasm, MRAS and Macro-80.
---
.Usage
zmac
[ --help ]
[ --version ]
[ --dep ]
[ --mras ]
[ --od dir ]
[ --oo sfx1,sfx2 ]
[ --xo sfx1,sfx2 ]
[ --rel ]
[ --rel7 ]
[ --doc ]
[ --zmac ]
[ -8bcefghijJlLmnopstz ]
[ filename[.z] ]

.Options

 --help
  Display a list of options and a terse description of what the options do.
 
 --version
  Print zmac version name.
 
 --mras
  MRAS compatibility mode.  Any _?_ in a label will be expanded to the
  current module identifier as set by _*mod_. Operator precedence@mrasord
  and results are changed.
 
 --od dir
  Place output files in _dir_ instead of the default "zout" subdirectory.
  Creates _dir_ if necessary.
 
 --oo hex,cmd
  Output only the the file types by suffix.  Multiple --oo arguments may
  be used.  "--oo lst,cas" is equivalent to "--oo lst --oo cas".
  See "Output Formats" for a list of output types by suffix@format.
 
 --xo tap,wav
  Do not output the file type types listed by suffix.
  
 --rel
  Output ".rel" (relocatable object file) format only.  Exported symbols are
  truncated to length 6.
 
 --rel7
  Output ".rel" (relocatable object file) format only.  Exported symbols are
  truncated to length 7.
 
 --zmac
  zmac compatibility mode.  _defl_ labels are undefined after each pass.
  Quotes and double quotes are stripped from macro arguments before expansion.
  _$_ is ignored in identifiers allowing _foo$bar_ to construct identifiers
  in macro expansions.  Use _`_ (backquote) instead in normal mode.  Labels
  starting with _"."_ are temporary and are reset whenever a non-temporary
  label is defined (thus they may be reused).  Labels starting with _"__"_
  are local to their file thus avoid multiple definition when brought in
  with _include_.
 
 --dep
  Print all files read by _include_, _incbin_ and _import_.
 
 --doc
  Print this documentation in HTML format to standard output.
 
 -Pk=number
  Set _@@k_ to the given numeric value before assembly.  Up to 10 parameters
  can be set from 0 though 9.  _-Pk_ is shorthand for _-Pk=-1_.
  For example, _P4=$123_ effectively puts _@@4 equ $123_ at the top of the
  first file.
 
 -8
  Accept 8080 mnemonics preferentially.  Equivalent to _.8080_ pseudo-op.
 
 -b
  Don't generate any machine code output at all.
 
 -c
  Make the listing continuous, i.e., don't generate any page breaks or
  page headers. Can make things less confusing if you're going to
  consult the listing online rather than printing it.  This is the default.
 
 -e
  Omit the "error report" section in the listing.
 
 -f
  List instructions not assembled due to "_if_" expressions being
  false. (Normally these are not shown in the listing.)
 
 -g
  List only the first line of equivalent hex for a source line.
 
 -h
  Display a list of options and a terse description of what the options do.
  (same as --help)
 
 -i
  Don't list files included with _include_, _read_ or _import_.
 
 -I dir
  Add _dir_ to the end of the include file search path.
 
 -j
  Promote relative jumps and _DJNZ_ to absolute equivalents as needed.
 
 -J
  Error if an absolute jump could be replaced with a relative jump.
 
 -l
  List to standard output.
 
 -L
  Generate listing no matter what. Overrides any conflicting options.
 
 -m
  List macro expansions.
 
 -n
  Omit line numbers from listing.
 
 -o filename.cmd
  Output only the named file.  Multiple "-o" options can be used to name a
  set of different files.
 
 -p
  Use a few linefeeds for page break in listing rather than ^L.
 
 -P
  Output listing for a printer with headers, multiple symbols per column, etc.
 
 -s
  Omit the symbol table from the listing.
 
 -t
  Only output number of errors instead list of each one.
 
 -z
  Accept Z-80 mnemonics preferentially.  Equivalent to _.z80_ pseudo-op.
---
.Input Format

zmac uses the standard Zilog mnemonics, and the pseudo-ops are also
largely as you'd expect.

A "_._" may optionally preceeed any psuedo-op.
For example, "_.org_" and "_org_" are treated as equivalent.

Input can be upper or lowercase.

Comments start with _;_ and carry on to the end of the line.

Number constants can take a trailing h or a leading $ or 0x for hex,
a trailing b for binary, a trailing o or q for octal, or a trailing
d for decimal.

_'LH'_ (any length 2 string) can be treated as a number whose value
is _'H'_ * 256 + _'L'_.

Labels are declared with _label:_ or just _label_ - indentation is unimportant.
Labels can be up to 40 chars long.  They can start with and contain 
letters, digits, _$_, _._, _?_, _@_ and __.  Ambiguous identifiers like
_$FCB_ will be treated as hex constants unless defined as a label.  Labels
declared with two colons (_label::_) make the label public.

Single quotes are ignored at the end of identifiers allowing non-binding
notation@prime indicating alternate register use during heavy applications
of _exx_ and _ex_.

Here is how other things work.  Numbers are used as examples, but a full
expression@expr can be used in their place.

..Data

_defb 42_
|A byte.  _ascii_, _byte_, _db_, _defm_ and _text_ are synonyms.

_defb 'foobar'_
|An ASCII character string (not NUL-terminated).
|Double quotes can also be used.

_defb 'Who needs anything more than CP/M?',13,10,'$'_
|Strings and bytes can mix together.

_defw 2112_

_defw $123,0x456_
|A word (16 bits).  _word_ and _dw_ are synonyms.

_defd $12345678_
|A double word (32 bits). _dword_ is a synonym.

_defs 500_
|Skip output ahead 500 bytes.  This will insert 500 zeros in the ".ams"
|and ".cim" output files or if inside a ".phase" section.
|_block_, _ds_ and _rmem_ are synonyms.

_dc 'string'_
|Like _ascii_ but accepts only a single string and the high bit of the
|last character will be set. _bytes_ is a synonym.

_dc count,value_
|Repeat the byte _value_ a total of _count_ times.  Similar to _defs_
|except that memory is always filled with _value_.

_incbin file_
|Inserts the raw contents of the file into the assembly.  Simpler for
|large amounts of data.

..Symbols

_label equ 100_
|Define a symbol to have a fixed value.  The symbol can be used before it
|is defined.  A symbol defined with _equ_ or as a label can be defined only
|once, except that a symbol defined with _equ_ may be redefined to the
|same value.

_varname defl 200_
|Define a symbol to have a changeable value.  The symbol cannot be used
|before it is defined, and it can be redefined to a different value later
|with another _defl_. _aset_, _set_ and _=_ are synonyms (despite _set_
|also being a Z-80 mnemonic).

_varname OP = expression_
|Shorthand for _varname defl varname OP expression_.  Allows for C-like
|handling of variable such as _var += 5_.  _OP_ can be _+_, _-_, _*_, _/_,
|_%_, _&_, _|_, _^_, _<<_, _>>_, _&&_ or _||_.

_varname++_
|Shorthand for _varname defl varname + 1_

_varname--_
|Shorthand for _varname defl varname - 1_

_min_

_max_
|Same as _defl_ except that the symbol is defined as the
|smaller or bigger of two comma-separated expressions.

_*mod_
|Increment the internal module name string.  The first time this results
|in "a".  Then "b", "c", ... "z".  Then "aa", "ab", "ac", etc. all the way
|up to "zzzz".  The module name string is used in _--mras_ mode where "?" in
|label names is replaced with the current module name.

_extern lab1,lab2,..._
|The listed labels are defined in an external module for later linking.
|No effect unless zmac is producing ".rel" output.
|_ext_ and _extrn_ are synonyms.

_public lab1,lab2,..._
|The given labels will be visible to external modules when linking.
|No effect unless zmac is producing ".rel" output.
|_global_ and _entry_ are synonyms.

_label ++_
|Equivalent to _label defl label + 1_.

_label --_
|Equivalent to _label defl label - 1_.

_label += 10_

_label -= 10_

|Equivalent to _label defl label + 10_ and _label defl label - 10_ respectively.
|Also works for _*=_, _/=_, _%=_, _|=_, _&=_, _^=_, _<<=_ and _>>=_.

..Location Control

_org 9000h_
|Set the address to assemble to 0x9000.

_phase address_
|Continue to produce code and data for loading at the current address
|but assemble instructions and define labels as if they originated at
|the given address.  Useful when producing code that will be copied to
|a different location before being executed (e.g., an overlay).

_dephase_
|End _phase_ mode assembly.

_aseg_
_cseg_
_dseg_
|Switch to the absolute, code and data segments respectively.
|No effect unless zmac is producing ".rel" output.

_common /name/_
|Set the address to the start of the selected common block.  The blank
|common block will be selected if name is empty or all blanks or
|omitted entirely.
|No effect unless zmac is producing ".rel" output.

..Input Control

_end_
|Ends the input.  Any lines after an _end_ are silently ignored.
|If an arg is given, it declares the entry address for the program.
|This has no effect in ".cim" output. In ".hex" output
|it generates an S-record directing 0 bytes of data to be loaded
|at the given address.  It is required for ".500.cas", ".1000.cas"
|and ".1500.cas" output.

_if_ ... [ _else_ ... ] _endif_
|For conditional assembly. If you do _if foo_ and _foo_ evaluates to
|zero, all the lines up until the next corresponding _else_ or _endif_
|are completely ignored.  Conversely, if _foo_ evaluates to non-zero, any
|lines from a corresponding _else_ to the _endif_ are ignored.  Ifs can
|be nested.  _cond_/_endc_ are synonyms for _if_/_endif_.

_ifdef symbol_
|Like _if_, but tests if _symbol_ has been defined.  Declaring a symbol
|as external counts as it being defined.

_ifndef symbol_
|Like _if_, but tests if _symbol_ has not yet been defined.

_import file_
|Like _include_ but will only bring in the file once.  File tracking is done
|using only the file name so, for example, an _import file_ will stop
|both _import ./file_ and _import dir/file_ even if they actually refer to
|different files.

_include file_
|Include a file. Like C's (well, cpp's) #include and follows the same
|include path search rules, but the filename arg
|lacks the angle brackets or quotes (though single or double quotes may be used).
|_read_ is a synonym.  _*include file_ also works if started in the first
|column.  In _--mras_ mode _".asm"_ will be added if _file_ has
|no suffix.

_maclib file_
|Like _include_ but adds _.lib_ to the file name so includes _file.lib_.

_comment X_
|Suspend assembly until the next occurence of character _X_ on a line.
|The rest of the line will be ignored.  A multi-line comment.

_assert expr_
|Stop assembly if _expr_ is non-zero.

..Cycle Counting

_sett expr_
|Set the current T-state count to _expr_. _tstate_ is a synonym.

_setocf expr_
|Set the current opcode fetch count to _expr_.

..Code Generation

_8080_
|Make cycle counting operators return 8080 cycle counts and
|interpret any ambiguous assembly statements as Intel 8080 mnemonics.
|_CP_ will be interpreted as "call on positive" and _JP_ as "jump on positive".

_z80_
|Make cycle counting operators return Z-80 cycle counts and
|interpret any ambiguous assembly statements as Zilog Z-80 mnemonics.
|_CP_ will be interpreted as "compare accumulator" and _JP_ as "jump unconditionally".

_jperror enable_
|If _enable_ is non-zero, turn on errors when _JR_ instructions could be used
|instead of _JP_, off otherwise.  Used to check existing code for situations
|where shorter code could be generated.  Same as _-J_ option.
|No effect if in 8080 mode.

_jrpromote enable_
|If _enable_ is non-zero, _JR_ and _DJNZ_ instructions will be promoted to
|equivalent _JP_ and _DEC##B_, _JP##NZ_ instructions if the relative branch
|offset is out of range.  If _enable_ is zero, promotion is disabled.
|Same as the _-j_ option.
|No effect if in 8080 mode.

..Undocumented Instructions\undoc

Most Z-80 chips support a number of undocumented instructions that were part of
the original design but not made an offical part of the Zilog specification.
These instructions may not be supported by all Z-80 chips, especially
licensed variants, but are fairly widely available nonetheless.

_sl1 r_
|Same as _sla r_ but shifts a 1 into the lower bit of _r_ rather than a 0.

_in (c)_
|Inputs a byte from port _c_ but does not store the value.  Flags are still
|set as with the normal _in r,(c)_ instruction.

_out (c),0_
|Outputs a zero to port _c_.

_bit/set/res n,(ix+d),r_

_rlc/rrc/rl/rr/sla/sl1/sra/srl (iy+d),r_
|Same as the corresponding operation on just _(ix+d)_ or _(iy+d)_ but with
|the result being stored both into _(ix+d)_ and register _r_.  Except for _bit_
|which has no effect on _r_. zmac supports the syntax to allow those
|instruction patterns to be generated.

The upper and lower bytes of the _ix_ and _iy_ can be used in a number of
instructions much in the same way as _d_ and _e_ correspond to the upper and
lower bytes of _de_.  zmac names these _ixh_, _ixl_, _iyh_ and _iyl_ and
are referred to generically as _ixylh_ here.

_inc/dec/add/adc/sub/sbc/and/xor/or/cp ixylh_
|Arithmetic or logical operation on _ix_ or _iy_ high or low byte.

_ld a/b/c/d/e,ixylh_
|Load register with _ix_ or _iy_ high or low byte.

_ld ixylh,a/b/c/d/e_
|Load _ix_ or _iy_ high or low byte with register.

_pfix_

_pfiy_
|Output $DD and $FD prefix bytes.  The Z-80 allows multiple prefix bytes
|for IX and IY instructions.  This allows you to specify them abstractly.
|There is little purpose except for delaying an interrupt or confusing
|disassemblers.

..Miscellaneous

_pragma str ..._
|Like C's #pragma, a generic hook for special purpose operations.  Only two
|are currently defined.

|_pragma bds rest-of-line_ to
|output _rest-of-line_ to the _.bds_ output file.

|_pragma mds rest-of-line_ to
|output _rest-of-line_ to the _.mds_ output file.

|The _.bds_ output format supports setting initial values for Z-80 registers
|and I/O ports so _pragma_ gives you access to that.

|The _.mds_ output format is a MAME debug script thus additional initial
|debugging commands may be output.  Of particular use on the TRS-80 Model II
|is _pragma mds ib@$ff=1_ which maps page 1 of RAM into $8000 .. $FFFF
|and thus allows programs to load into that area.

_name str_
|Set the name of the output module to _str_.  For compatibility reasons
|_str_ may be parenthesized (e.g., "_name ('foo')_").  Not all output
|formats support an internal name and many have severe length limits.

_rsym_ and _wsym_
|Read/write a symbol file. These simply load/save the currently defined
|symbols from/to the file specified (in a non-portable format). _rsym_
|takes place at the point it is encountered in the file (on the first
|pass); _wsym_ is delayed until assembly has finished.

..Listing Pseudo-ops

There are several pseudo-ops for controlling the listing. None of
these ops appear in the listing themselves:

_eject_
|Start a new listing page.

_nolist_
|Do nothing. This can be used to have a comment in the source but not
|the listing, I suppose.

_elist_, _flist_, _glist_, _mlist_
|These have the same effect as the similarly-named command-line
|options, though possibly with the sense reversed depending on the
|default. Use an arg >0 (or no arg) to enable, and an arg <0 to
|disable.

_list arg_
|Turns output to listing file (.list) off if _arg_ < 0 or on if _arg_ > 0.
|If no _arg_ supplied then listing is enabled.
|Use this to avoid listing certain parts of the source.
|In _--mras_ mode _arg_ must be either _on_ or _off_ and
|_*list_ can be used if started in the first column.

_title_
|Set title (used in listing and symbol file).

_space arg_
|Output arg blank lines in the listing, or one line if no arg is given.

---

.Expressions\expr

Expressions feature a full set of C operators with the same precedence
rules and some common assembler extensions and names.
Here is the complete list of operators, highest-precedence first.
Operators separated only by a space are synonyms; for example, _~_
is the same as _not_.

_!_ (logical), _~ not_ (bitwise), _+_ (unary), _-_ (unary), _low_, _high_, _t_, _tilo_, _tihi_, _ocf_

_*_, _/_, _% mod_

_+_, _-_

_<< shl_, _>> shr_

_< lt_, _> gt_, _<= le_, _>= ge_

_== = eq_, _!= <> ne_

_& and_ (bitwise)

_^ xor_ (bitwise)

_| or_ (bitwise)

_&&_

_||_

_? :_  (ternary choice operator)

Expressions\mrasord change significantly in _--mras_ mode:
|Evaluation is strictly left to right.  Except for _and_, _or_,
|_xor_ and _=_.  This doesn't break compatibility as original MRAS
|source code only allows _.and._, _.or._ and _.xor._ but the precedence
|difference may surprise if code is added.

|_!_ is bitwise OR instead of logical not.

|_<_ is left shift (or right shift when shift amount is negative)

|MRAS operators (_.and._ _.eq._ _.ge._ _.gt._ _.high._ _.le._ _.low._
|_.lt._ _.mod._ _.ne._ _.not._ _.or._ _.shl._ _.shr._ _.xor._)
|are recognized even if apparently in identifers.  (e.g., _a.or.b_ is
|seen as _a .or. _b).

|Logical operators return -1 for true and 0 for false.  Normally
|zmac, like C, uses 1 for true.

You can use normal parentheses or square brackets to override
the precedence rules. Square brackets can be used where parentheses would
conflict with Z-80 mnemonic syntax, but this is not necessary in any
practical case.

The _?_ may need spaces around it to distinguish it from a label that
has _?_ in it.

The unary operators not familiar to C programmers:

 low expr
  Returns low 8 bits of _expr_
 
 high expr
  Returns high 8 bits of _expr_
 
 t expr
  Current count of T-states up to memory location _expr_
 
 tilo expr
  Low count of T-states used by instruction at memory location _expr_
 
 tihi expr
  High count of T-states used by instruction at memory location _expr_
 
 ocf expr
  Current count of opcode fetches up to memory location _expr_
---
.Macros
The following defines a macro named m with zero or more formal parameters
_p1_, _p2_, ..., _pn_, zero or more local symbols _?s1_, _?s2_, ..., _?sm_,
and body _b1_, _b2_, ...:

 _m macro p1, p2, ..., pn, ?s1, ?s2, ..., ?sm_
  
 _####b1_
  
 _####b2_
  
 _####..._
  
 _####endm_

The macro is called by writing:
|_m v1, v2, ..., vn_

A macro call expands to the text of the macro's body, with each 
occurrence of a formal parameter _pk_ replaced by the corresponding 
value _vk_, and with each local symbol _?sk_ replaced by a new, unique 
symbol invented for this call.  Invented symbols begin with _?_,
so you should avoid using such symbols elsewhere in your program.

zmac currently does not check that you have provided the right number 
of parameters when calling a macro.  If you provide too few, unmatched 
formals are replaced with the empty string.  If you provide too 
many, the additional values begin to replace local symbols as if 
they were ordinary parameters.  (This could be considered a feature.)  
After the local symbols are all replaced, additional parameters 
are silently ignored.

For compatibility with Macro-80, the first line of a macro definition can
list other labels that will be treated locally:

|_####local lab1,lab2,..._

Each time the macro is expanded the local labels are replaced with unique
names thus avoiding multiple definition problems.

For compatability with MRAS, macro arguments may be preceeded by _#_
in their definition and use.

Any _`_ (backquote) in a macro is ignored thus allowing a macro to
construct identifiers.  For example:

 _move macro dir_
  
 _######ld`dir`r_
  
 _######endm_

Invoking _move i_ will construct a _ldir_ block move instruction.

For compatibility, _&_ can also be used as in MAC to concatenate
macro parameters.  This conflicts with zmac's bitwise and operator but
you can use the _and_ synonym in macros to avoid the conflict.

In _--mras_ mode arguments will be expanded even if they are inside other
identifiers.  The _move_ could be written:

 _move macro dir_
  
 _######lddirr_
  
 _######endm_

Macro definitions can contain macro definitions which will be defined
when the outer macro is first exapnded.  Macros can be redefined as
well.

Macro expansion continues to the _endm_ directive but can be stopped
prematurely by the _exitm_ directive.  Typically the _exitm_ is inside
some conditional part of the macro.

Parameters passed to a macro can be empty and are tested with the _nul_
operator:

 _if nul &par_
  
 _..._
  
 _endif_

Macro parameters can contain commas if grouped inside _<_ and _>_.
Or a comma can be escaped with _^_ which can also escape spaces and other
special characters.  It is also be put in front of a macro parameter
name inside the expansion to suppress the replacement by its value.

Expansion of parameters in a macro body is purely textual.  This can
lead to surprises in complex situations.  The _%_ character can be used
to force a macro parameter to be replaced with the evaluation of it
as an expression.


..Inline Macros

zmac supports the commonly available _rept_, _irp_ and _irpc_ inline macros

_rept_ repeats its block the given number of times.  This will output 10
_nop_ instructions:

 _rept 10_
  
 _######nop_
  
 _endm_

_irpc_ runs through a string of letters assigned them to a variable and
expanding the macro block each time.  For example, this will load 7 into
registers _b_, _d_ and _h_:

 _irpc reg,bdh_
  
 _######ld &reg,7_
  
 _endm_

_irp_ runs through a list of parameters assiging each entry to a variable
and expanding the macro block.  Here we load _bc_, _de_ and _hl_ with 0:

 _irp rpair,<bc,de,hl>_
  
 _######ld &rpair,0_
  
 _endm_

Lists can be nested.  Here's an example of and _irp_ passing lists on down
to another _irp_:

 _irp listlist,<<one,two,three>,<four,five,six>>_
  
 _irp list,<listlist>_
  
 _ascii '&list'_
  
 _endm_
  
 _endm_


---
.Compatibility

zmac is broadly compatible with many original Z-80 and 8080 assemblers
because it accepts many different names for common operations and has
liberal identifier and numeric formats.  It also accepts most simple
usage of macros.

When assembling old code keep these portability problems in mind.

Expression order of evaluation may be different.  zmac uses C semantics
more order of evaluation but assemblers often used simple left to right
ordering.  zmac will evaluate _2+2*3_ as _8_ where other assemblers will
yield _12_.  However, in _--mras_ mode expressions are evaluated strictly
left-to-right for compatibility.

zmac has no support operating on strings in macros.  Assemblers like Macro-80
could perform conditional tests on strings.

Advanced macros are unlikely to work.  zmac hasn't advanced to the state where
all the possible ways of substituting parameters are supported.

Consult the original assembler manual.  zmac error messages won't help you
figure out what an unknown assembler command is supposed to do.

Compare against original output.  The very safest thing to do when porting
assembly code is to compare the binary output of zmac against that produced
by the original assembler.  This way you can ensure everything has been
interpreted correctly.  Only once that has been achieved should you modify
the code.
---
.Errors and Warnings

Any errors or warnings encountered during assembly are reported to standard
error and in the listing file.  The errors output immediately give the source
file and line number containing the error.  In listings the error letter
and message appear just after the line containing the error.

 B
  Balance error
 ##
  A string is missing an closing quote or an _if_ is missing an _endif_
 E
  Expression error
 ##
  An expression did not parse or attempts a divide or modulus by 0.
 F
  Syntax error
 ##
  General problem with the syntax on a line.  Sometimes extra explanation
  will be printed on standard output.
 I
  Digit error
 ##
  A numeric constant has too many digits to be represented as a 32 bit number.
 M
  Mult. def. error
 ##
  A symbol has been defined more than once and those values differ.
 P
  Phase error
 ##
  On the second or subsequent assembly passes the assembly has changed
  significantly.  Most commonly it means an _if_ has changed conditions
  but can also happen when labels or equated values do not converge to
  a fixed value.
 U
  Undeclared error
 ##
  An undeclared symbol was used in an expression or _public_ statement.
 V
  Value error
 ##
  An invalid value was given to a statement.  Often this means using less
  than -128 or greater then 255 in a _defb_ or less than -32768 or greater
  than 65535 in a _defw_.  Or similar invalid values used Z-80/8080 opcodes
  requiring an 8 or 16 bit value (and other restrictions like 0 to 7 for _BIT_).
  Also if a relative jump is out of range or if a negative value is given
  in _defs_ or _dc_.
 O
  Phase/Dephase error
 ##
  _phase_ was used within another _phase_ or _dephase_ without _phase_.
  Or if _org_ is used within _phase_.
 A
  Assertion failure error
 ##
  An assert statement evaluated to zero.
 J
  Use JR error
 ##
  An absolute jump instruction was used where relative jump was in range
  of the destination address.  Only generated if _-j_ or _jrpromote_ is
  in effect.
 R
  Not relocatable error
 ##
  An expression was used that must be generated at link time but cannot
  be handled by the ".rel" format.  For instance, an _org_ to a symbol in
  the data segment when in the code segment.  Or a relative jump to a
  different segment.  The ".rel" format can evaluate expressions at link
  time using the _high_, _low_, _not_, _-_, _+_, _*_, _/_ and _%_ operators.
  zmac is clever enough to use _high_ or _low_ in place of _& $ff00_ and
  _& 255_.  But it won't replace a _shl_ with a multiply.
 G
  Register usage error
 ##
  A invalid register was given to an instruction.  For example, _LD B,(DE)_
  or _ADD HL,IX_.
 Z
  Z-80 instruction in 8080 mode error
 ##
  An instruction was assembled that is only valid on the Z-80 but _.8080_
  (or _-8_) mode is in effect.  However, use use of Z-80 mnemonics that
  output valid 8080 instructions is always OK.
 H
  $hex constant interpreted as symbol warning
 ##
  A symbol such as _$FCB_ has been defined even though it could appear to
  be a hexadecimal constant.  zmac will treat _$FCB_ as symbol for the entire
  assembly which could be rather surprising if that were not the intent.
 N
  Not implemented warning
 ##
  For statements that have been added as parse rules but have no effect.
  The only current example is _subttl_ which sets the sub title of a listing
  in certain assemblers.

---
.Output Formats\format

Except for ".rel", zmac writes every known output when assembling by default.
This is no burden on modern computers and saves having to meticulously select
the desired output format.

".rel" is a special case since that format is intended for linking and
can have undefined external symbols which would be errors in the other formats.
Conversely, a simple "org $8000" will be an error for ".rel" output as it
defaults to the code segment where absolute origin statements are forbidden.

If ".rel" is selected for output either by _--relopt_ or with
_--oo rel_ or _-o file.rel_ then all other output formats are suppressed
(except the ".lst" source file listing).

 .ams
  AMSDOS executable format for Amstrad computers.
 .bds
  For source-level debugging in trs80gp@http://www.48k.ca/trs80gp.html
 .1500.cas
  TRS-80 high-speed (1500 baud) cassette SYSTEM file.  The internal name of the
  file is the source file name shortened to 6 characters with suffixes
  removed.  Requires an entry address.
 .250.cas
  TRS-80 250 baud cassette Level I CLOAD file.  If your program has an
  entry address and $41FE does not contain that entry address then the file
  will be loaded at $41FE with relocation code added to move it to the desired
  location.
 .500.cas
  TRS-80 low-speed (500 baud) cassette SYSTEM file.  The internal name of the
  file is the source file name shortened to 6 characters with suffixes removed.
  Requires an entry address.
 .1000.cas
  Identical to 500 baud but intended for double-speed LNW-80 which can
  can load cassette files at double speed for an effective 1000 baud rate.
  Requires an entry address.
 .cim
  Core In-Memory image.  A raw binary format with the first byte corresponding
  to the lowest generated code or data and proceeding contiguously until the
  highest address generated.  Any gaps are filled with zeros.  Typically used
  for CP/M where all executables start at address 256 or for ROM images.
 .cmd
  TRS-80 DOS executable file format as used by all major DOSes on the TRS-80
  (TRS-DOS, LDOS, MULTIDOS, NEWDOS, etc.)
 .hex
  Intel hex record format.
 .rel
  Relocatable object module format as produced by MACRO-80 and other assemblers.
 .tap
  ZX Spectrum cassette tape format.
 .1500.wav
  Same as .1500.cas but in ready-to-play audio format.
 .250.wav
  Same as .250.cas but in ready-to-play audio format.
 .500.wav
  Same as .500.cas but in ready-to-play audio format.
 .1000.wav
  Same as .1000.cas but in ready-to-play audio format.
 .mds
  MAME debug script (e.g., mame trs80 -d -debugscript zout/prog.mds)

---
.Miscellaneous
In the symbol table listing, the _=_ prefix is given for those symbols
defined by _equ_ or _defl_.  The _/_ prefix is shown for common blocks.

The _.rel_ file format can store symbol names of up to 7 characters in length.
However, MACRO-80 truncates symbols to 6 characters so that it has one
character in reserve for extending linking operations such as subtracting
two externals from each other.  To be compatible (and sensible), _--rel_
truncates externals to 6 characters.  For MRAS compatibility, _--mras_
truncates symbols to 7 characters.  This is not a problem for MRAS as it
doesn't support extended linking.  But necessary if you want zmac to produce
_.rel_ files that will link with MRAS generated _.rel_ files.  The _--rel7_
option sets symbol truncation to 7 characters so you can assemble files
that will link with MRAS output.  However, it will break extended linking
on labels longer than 6 characters.

The ignoring\prime of single quotes can be handy for tracking alternate
register usage.  Consider the following code fragment:

 _ld    a,(hl)_
  
 _rra_
  
 _exx_
  
 _ld    a,(hl')_
  
 _ex    af,af'_
  
 _ld    a',(hl')
  
 _rra'_
  
 _ex    af,af'_
  
 _djnz' loop_
  
 _ld    d',e'_
  
 _exx_

Although zmac does nothing but ignore the single quotes they are useful for
indicating which register we're talking using.  A more advanced mode
where zmac pays attention to the trailing quotes and emits exchange instrucitons
as needed has been considered.

---
.Exit Status

 0
  No errors.
 1
  One or more errors were found during assembly, or zmac exited with a
  fatal error.

--
.Credits
Bruce Norskog originally wrote zmac in 1978.

Updates and bugfixes over the years by John Providenza, Colin Kelley,
and more recently by Russell Marks, Mark RISON, Chris Smith,
Matthew Phillips and Tim Mann.

Extensive modifications for cycle counting, multiple output formats,
".rel" output, 8080 mode and older assembler compatibilty were written
by George Phillips.

This document was based on Russell Marks zmac man page which had
tweaks by Mark RISON and Tim Mann.  George Phillips converted it to HTML
and documented the new features and some older ones (e.g., _phase_/_dephase_).