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Kingswood Software Development Tools                                 AS80
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NAME
   as80 - assembler for 8080, 8085 and Z80 microprocessors.


SYNOPSIS
   as80 [-cdghilnopqstvwxz] file


DESCRIPTION
   This documentation is for as80 [1.10].
   Copyright 1990-1994, Frank A. Vorstenbosch, Kingswood Software.

   AS80 is an assembler for the Intel 8080/8085 and Zilog Z80
   microprocessors.  It reads input from an ASCII text file, assembles
   this into memory, and then writes a listing and a binary or hex file.

   AS80 is case sensitive, not only does it differentiate between the
   labels XYZ and xyz, but it also requires all (pseudo) instruction and
   register names to be lower case.  This way, the listing is the most
   readable.  Option -i can be used to make the assembler case insensitive.
   Alternatively, the included TOLOWER program can be used to convert
   sources to lower case.


OPTIONS
   As80 recognizes the following options:

      -c   Show number of cycles per instruction in listing.  This
           decreases the number of columns available for listing by 5.
           The number of cycles is printed between brackets [ and ].

      -d<name>
            Define a label before the first source line is read.  If
            no name is specified, DEBUG is defined.  The label is
            EQUated to be 1.

      -g   Generate source-level debug information file.  This file
           can then be used in in-system debugging or a software
           simulator.

      -h<lines>
           Specify height of page for listing.  This option determines
           the number of lines per printed page.  Each page has a header
           and is terminated by a form-feed character.  The special
           case -h0 indicates an infinite page length.  In this case,
           page breaks are only inserted between the two passes and
           the symbol table (if present).

      -i   Ignore case in opcodes.  In this way, the assembler does not
           differentiate between 'add' and 'ADD', for example.  Labels
           are still case sensitive.

      -l   Generate pass 2 listing.

      -l<filename>
            Listing file name.  The listing file is used for pass 1 and
            pass 2 listing, for the symbol table (printed between the
            two passes), and some statistics.  When neither -p nor -t
            is specified, and -l<filename> is given, then the assembler
            automatically generates a pass 2 listing.  When -p or -t is
            specified, an additional -l should be given is a pass 2
            listing is required.  The filename - can be used to direct
            the listing to standard output.

      -l   Generate pass 2 listing.

      -m   Show macro expansions in listing.  Macro lines are prefixed
           by a > sign.

      -n   Disable optimizations.  When this option is specified no
           optimizations will be done, even when the OPT pseudo-
           instruction is used in the source code.

      -o<filename>
           Specify binary or s-records output file name.  The assembler
           automatically adds ".bin" for binary output or ".s19" for
           s-records output when no extension is given.

      -p   Generate pass 1 listing.  This may be used to examine any
           optimizations/bugs generated in pass 2.

      -q   Quiet mode.  No running line counter is displayed on standard
           error output.

      -s   Write s-records instead of binary file.  The s-records file
           contains data for (only) the used memory; the binary file
           begins at the lowest used address, and continues up to the
           highest used address; filling unused memory between these
           two addresses with either $ff or $00.

      -s2  Write intel-hex file instead of binary file.  The intel-hex
           file contains data for (only) the used memory.

      -t   Generate symbol table.  The symbol table is listed between
           passes one and two, displaying the name, hexadecimal and
           decimal value of each label, using 4-digit hexadecimal
           numbers where possible, otherwise 8-digit numbers.  The
           decimal value is followed by an asterisk if the label is
           redefinable (defined using SET instead of EQU).

      -v   Verbose mode.  More information is displayed on standard
           output.

      -w<width>
           Specify column width.  Normally, the listing is printed using
           79 columns for output to a 80-column screen or printer.  If
           the -w option is given without a number following it, then
           the listing will be 131 columns wide, otherwise it will be
           the number of colulmns specified (between 60 and 200).

      -x1  Use 8085 extensions.  The 8085 CPU has two additional 
           instructions and different cycle counts, but is otherwise
           software compatible to the 8080.  When this option is not 
           specified the assembler rejects the RIM and SIM instructions.

      -x   or
      -x2
           Use Z80 extensions.  The Z80 has many additional instructions
           and addressing modes, but is otherwise software compatible to 
           the 8080.  When this option is not specified the assembler 
           rejects all Z80 new instructions and addressing modes.

      -x3  Use Z80 extensions and index register byte instructions.
           The IX and IY registers were originally intended to be
           split in IXH/IXL and IYH/IYL register pairs.  For some
           reason (bug in original mask set?) these instructions were
           not included by Zilog in the programming manuals, but
           they do work on all CPUs I've seen.  Your mileage may vary.
           Note that these extensions do NOT work on the Z180/181 and
           H64180, but they DO (and are documented) on the Z280.

      -z   Fill unused memory with zeros.  Normally when a binary file
           is generated, unused bytes between the lowest and highest
           used addresses are filled with $ff, the unprogrammed state
           of EPROMs.  If this is not wanted, the -z option can be used
           to initialize this memory to $00.  With s-records, unused
           memory is not output to the file, and this option forces the
           creation of an S9 (start address) record instead, even if no 
           start address is specified in the file with the END pseudo-
           instruction.

   Commandline options can be catenated, but no other option can follow
   one that may have a parameter.  Thus:
      -tlfile
   is correct (specifying symbol table and pass 2 listing), but
      -h5t
   is not.

   It is possible to discard any of the the output files by specifying
   the name 'nul'.


EXPRESSIONS

   The assembler recognizes most C-language expressions.  The operators
   are listed here in order of precedence, highest first:

       ()            braces to group subexpressions
       * $           current location counter
       unary + - ! ~ unary + (no-operation), negation, logical NOT,
                     binary NOT
       * / %         multiplication, division, modulo
       + -           addition, subtraction
       << >>         shift left, shift right
       < > <= >=     comparison for greater/less than
       = !=          comparison for equality (== can be used for =)
       &             binary AND
       ^             binary XOR
       |             binary OR
       &&            logical AND
       ||            logical OR
       hi lo         high byte, low byte

   The logical NOT (!) evaluates to zero if the parameter is nonzero,
   and vice versa.  The binary NOT (~) complements all the bits in its
   parameter.  Logical AND (&&) and OR (||) operators evaluate to one
   if both resp. at least one argument is nonzero.  These two operators
   evaluate both arguments, unlike the C-language versions.

   Note: the asterisk is both used as the multiplication operator, and
   as symbol for the current location.  The assembler determines from
   the context which is which. Thus:

       5**

   is a valid expression, evaluating to five times the current location
   counter, and:

       2+*/2

   is too, evaluating to the current location counter divided by two, to
   which two is added.  In the same way, the % sign is both used as the
   modulo operator and the prefix for binary numbers.

   Numbers can be specified in any number base between 2 and 36.
   Decimal numbers can be used without a prefix, hexadecimal numbers
   can be prefixed by $, octal numbers by @, and binary numbers by %.
   Other number bases can be used by using the following format:  
      <base>#<number>, 
   where the base is the number base to use (must be specified in 
   decimal), and number is the value.  Thus:
      1000    - decimal number, value 10*10*10=1000
      %1000   - binary number, value 2*2*2=8
      @1000   - octal number, value 8*8*8=512
      $1000   - hexadecimal number, value 16*16*16=4096
      #1000   - hexadecimal number, value 16*16*16=4096
      0b1000  - binary number, value 2*2*2=8
      0x1000  - hexadecimal number, value 16*16*16=4096
      2#1000  - binary number, value 2*2*2=8
      4#1000  - base-4 number, value 4*4*4=64
      7#1000  - base-7 number, value 7*7*7=343
      36#1000 - base-36 number, value 36*36*36=444528
   For number bases greater than 10, additional digits are represented
   by letters, starting from A.  Both lower and upper case letters can
   be used.
      11#aa = 120
      16#ff = 255
      25#oo = 624
      36#zz = 1295


PSEUDO-INSTRUCTIONS

   align <expression>

      Align fills zero or more bytes with zeros until the new address
      modulo <expression> equals zero.  If the expression is not present,
      align fills zero or one bytes with zeros until the new address
      is even.

      Example 1:
                      align  256             ; continue assembly on the
                                             ; next 256-byte page

      Example 2:
                      align                  ; make sure table begins
      Table           dw     1,2,3           ; on an even address



   bss

      Put all following data in the bss segment.  Only data pseudo-instructions 
      can be used in the bss segment, and these only increment the location 
      counter.  It is up to the programmer to initialize the bss segment.  The 
      bss segment is especially meaningful in a ROM based system where
      variables must be placed in RAM, and RAM is not automatically initialized.

      The assembler internally maintains three separate location counters,
      one for the code segment, one for the data segment and one for the
      uninitialized data segment.  The user is responsible for not overlapping
      the segments by setting appropriate origins.  The code, data and bss
      pseudo-instructions can be used to interleave code and data in the source
      listing, while separating the three in the generated program.  The
      assembler starts with the code segment if none is specified.

      Example:
                     code
                     org    $f000           ; Assuming 4 kbyte code ROM
                     data                   ; with 2 kbyte program and
                     org    $f800           ; 2 kbyte initialized data
                     bss
                     org    0               ; bss segment is in RAM

      Buffer         ds     100

                     code
      Begin          ld     hl,Table
                     ld     de,Buffer
                     ld     bc,3
                     ldir
                     .
                     .
                     .

                     data
      Table          db     1,2,3

                     code
      MyFunc         ld     ix,Table
                     .
                     .

   code

      Put all following assembled instructions and data in the code segment.
      See BSS.


   data

      Put all following assembled instructions and data in the data segment.
      See BSS.


   db <bytelist>

      Define bytes.  The bytes may be specified as expressions or strings,
      and are placed in the current (code or data) segment.  This pseudo
      instruction is similar to the Zilog-defined defb and defm pseudo-
      instructions.

      Example:
      Message        db     "\aError\r\n",0


   defb <bytelist>

      Define bytes.  The bytes may be specified only as expressions, 
      and are placed in the current (code or data) segment.  This 
      pseudo-instruction is similar to the db pseudo-instruction.

      Example:
      Message        defb   7
                     defm   "Error"
                     defb   13,10,0


   defm <string>

      Define message.  The bytes may be specified only as a string, and
      are placed in the current (code or data) segment.  This pseudo-
      instruction is similar to the db pseudo-instruction.


   ds <expression>
   defs <expression>

      Define zero or more bytes empty space.  The specified number of
      bytes are filled with zeros.  This pseudo-instruction is identical
      to the Zilog-defined pseudo-instruction defs.

      Example:
                     ds     100             ; reserve 100 bytes here


   dw <wordlist>
   defw <wordlist>

      Define words.  The words are placed in the current (code or data)
      segment.  This pseudo-instruction is identical to the Zilog-
      defined defw pseudo-instruction.

      Example:
                     ld     a,2*Function    ; number of function
                     ld     hl,JumpTable
                     add    a,l             ; calculate HL+A
                     ld     l,a
                     adc    a,h
                     sub    l
                     ld     h,a
                     jp     (hl)            ; jump to function

      JumpTable      dw     Function0
                     dw     Function1
                     dw     Function2


   else

      The else pseudo-instruction can be used for if-then-else
      constructions. It must be placed between an if and an endif
      instruction.  For an example, see the if pseudo-instruction.


   end <expression>

      The end pseudo-instruction is optional, and need not be used.  If
      it is used, its optional operand specifies the staring address of
      the program.  This address is displayed when the program is
      assembled, and is also placed in the s-record output file.

      Example:
                     end    Start

   endif

      The endif pseudo-instruction must be used to close an if-endif
      or if-else-endif construction.  For an example, see the if
      pseudo-instruction.


   <label> equ <expression>

      The equ (equate) pseudo-instruction sets the specified label to
      the value of the expression.  The label may not already exist.
      Some programmers choose to use only upper-case identifiers for
      labels defined in this way to differentiate them from addresses.

      Example:
      ESCAPE          equ    27


   if <expression>

      The if pseudo-instruction can be used in conjunction with the
      endif and possibly the else pseudo-instructions to selectively
      enable and disable pieces of code in the source.  If the expression
      given evaluates to zero, then the following code up to the matching
      else or endif is not included in the assembly.  If the expression
      is nonzero, then the following code is included, but any code
      between the matching else and endif is not.
      The original Zilog assemblers called this pseudo-instruction COND.

      Example:
                     if COUNT=2 | COUNT=4
                     add     a,a            ; shift left for counts
                     if COUNT=4             ; of 2 and 4
                     add     a,a
                     endif
                     else
                     ld      b,COUNT        ; otherwise use slow multiply
                     call    Multiply
                     endif


   include <string>

      The named file is included in the assembly at this point.  After
      it has been read, assembly continues with the next line of the
      current file. Include files may be nested.

      Example:
                     include "z180.i"


   list

      Enable generation of the listing in the list-file.  If the listing
      has been disabled twice, it must be enabled twice before it is
      generated.  When no -p or -l option has been specified on the
      command line, this pseudo-instruction has no effect.


   macro

      Define a macro.  Macros allow a block of source statements to be
      given a name, and then that name can be used to include the
      statements anywhere in the program.  Parameters can be used to
      pass arguments to the macro.  In the macro definition names
      can be used to respresent the arguments; these names in the text
      are substituted with the value passed on macro expansion.
      Macro arguments can also be represented by using \1 through \9
      in the macro text; these sequences are replaced by the first
      through ninth argument respectively.  The special value \0
      contains the number of arguments passed to the macro.

      Example 1:
      Macro1         macro  text,value
                     dw     value
                     db     text,0
                     db     "value=",'value',0
                     endm

      Macro2         macro
                     dw     \2
                     db     \1,0
                     db     "value=\2",0
                     endm

                     Macro1 "Hello",123
                     Macro2 "Hello",123

      Macros can also use local labels, for when a unique label is needed
      each time the macro is expanded.  This can be used when the macro
      contains a conditional jump, or a loop of some kind, or simply needs
      to reference some data.  Local labels can be declared by using the
      local pseudo-instruction, or by using the \? special value.  The
      \? value is replaced by a unique four-digit decimal number each
      time a macro is used.
      
      Example 2:
      Macro3         macro  text
                     local  String
                     code
                     dw     String
                     data
      String         db     text,0
                     endm

      Macro4         macro  text
                     code
                     dw     String\?
                     data
      String\?       db     text,0
                     endm

                     Macro3 "Hello"
                     Macro4 "Hello"

      Macros can also contain if...endif statements, and the exitm
      pseudo-instruction can be used to terminate macro expansion.
      Macros can also call other macros (or themselves) up to a nesting
      depth of 15 levels.

      Macro5         macro  count
                     if     count>25
                     exitm
                     endif
                     db     10*count
                     endm

                     Macro5 10
                     Macro5 100


   nolist

      Disable generation of the listing in the list-file.


   noopt

      Disable optimizations.  If the -n option has been specified on the
      command line, this pseudo-instruction has no effect.


   nop <expression>

      No operation.  When the optional expression is not present, this
      is simply the nop instruction of the processor.  When the
      expression is present, the specified number of nop instructions
      are inserted.

      Example:
                     nop    10


   opt

      Enable optimizations.  If the -n option has been specified on the
      command line, this pseudo-instruction has no effect.
      When optimization is enabled, the assembler tries to use the
      shortest and fastest instructions possible which have the effect
      the user wants.  It may replace any extended-address instruction
      by direct-address instructions (provided the direct pseudo-
      instruction has been used).  It replaces long branches with jumps
      or short branches, calls with branches to subroutines, and
      replaces zero-offset indexed instructions by no-offset indexed
      instructions.  The effects of optimizations is clearly visible if
      both a pass one and a pass two listing is generated.


   org <expression>

      The org (origin) pseudo-instruction specifies the next address to
      be used for assembly.  When no origin has been specified, the
      assembler uses the value 0.  The assembler maintains three separate
      location counters: one for the code segment, one for the data
      segment, and one for the bss segment.  See the code and pseudo-
      instruction for more information.


   page <expression>

      When the optional expression is not present, the assembly listing
      is continued on the next page.  When the expression is present,
      the listing is continued on the next page only if the specified
      number of lines do not fit on the current page.


   <label> set <expression>
   <label> = <expression>

      The set pseudo-instruction sets the specified label to the value
      of the expression.  The label may or may not already exist.
      Some programmers choose to use only upper-case identifiers for
      labels defined in this way to differentiate them from addresses.

      Example:
      CURRENT         set    0

                      .
                      .
                      .

      CURRENT         set    CURRENT+1


   struct <name>
   struct <name>,<expression>

      The struct (structure) pseudo-instruction can be used to define
      data structures in memory more easily.

      The name of the structure is set to the total size of the structure;
      if the expression is present, the starting offset is the value of
      the expression in stead of zero.

      Between the struct and end struct pseudo-instructions the following
      pseudo-instructions can be used: db, dw, ds, label, align.
      Within structures these pseudo-instructions take a slightly different
      format than normally:

         db <name>                element is one byte

         dw <name>                element is two bytes

         ds <name>,<expression>   element is the specified number of bytes

         ds <expression>          skip the specified number of bytes

         label <name>             element is zero bytes, i.e. set the name
                                  to the current structure offset

         align <expression>       skip until (offset%expression)=0

         align                    skip until offset is even


      Example:
                     struct ListNode,4
                     dw     LN_Next
                     dw     LN_Previous
                     db     LN_Type
                     align
                     label  LN_Simple       ; size of structure so far
                     align  8
                     ds     LN_Data,10
                     end struct

      This is identical to:

      LN_Next        equ     4       ;\
      LN_Previous    equ     6       ; offset of structure elements
      LN_Type        equ     8       ;/
      LN_Simple      equ     10      ; size of structure so far
      LN_Data        equ     16      ; offset of structure element
      ListNode       equ     26      ; size of structure


   title <string>

      The title pseudo-instruction sets the title to be used in the
      header of each listing page.  The string should be no longer than
      80 characters.

      Example:
                   title  "DIS80 : A disassembler for a 8080 CPU"


ADDRESSING MODES
   The assembler allows all 8080 (and when enabled also Z80) addressing
   modes.  The use of an expression between braces as an address disallows
   braces at the outermost level for immediate values.  The assembler
   is capable to determine that

                   ld     a,(10)+1
   and
                   ld     a,1+(10)

   are immediate operands.  You can also use rectangular brackets
   [ and ] to include an address.

   List of available modes:
      immediate
      (address)
      (bc) (de) (hl) (sp)

   Additional addressing modes for the Z80 and Z180:
      (ix+offset)  (ix-offset)
      (iy+offset)  (iy-offset)
      (c)


LIST OF ACCEPTED INSTRUCTIONS
   adc add align and bit bss call ccf code cp cpd cpdr cpi cpir cpl daa 
   data db dd dec defb defm defs defw di disable djnz ds dw ei else enable 
   end endif equ ex exx fcb fcc fcw fdb halt if im in inc include ind indr 
   ini inir jp jr ld ldd lddr ldi ldir list neg nolist noopt nop opt or 
   org otdr otir out outd outi page pop push res ret reti retn rim rl rla 
   rlc rlca rld rmb rr rra rrc rrca rrd rst sbc scf set shl shr sim sl sla 
   sr sra srl stc struct sub title tsti xor 

   Of these instructions, the following are (more or less) synonymous,
   and can be used interchangably.
   YOU CAN USE      WHERE YOU WOULD PREVIOUSLY USE
      nop 6      -  nop nop nop ....
      push bc,de -  push bc ; push de
      pop bc,de  -  pop de ; pop bc  (note reversed order)
      disable    -  di
      enable     -  ei
      sr         -  srl
      shr        -  srl
      sl         -  sla
      shl        -  sla
      stc        -  scf
      ld bc,de   -  ld b,d ; ld c,e
      ld ix,bc   -  ld xh,b ; ld xl,c
      add R      -  add a,R
      or a,R     -  or R
      in (c)     -  tsti (c)
      ex hl,de   -  ex de,hl
      djnz LBL   -  dec b ; jp nz,LBL
      jp nv,LBL  -  jp pe,LBL  (no overflow/parity even)
      jp v,LBL   -  jp po,LBL  (overflow/parity odd)
      jp ns,LBL  -  jp p,LBL   (no sign/positive)
      jp s,LBL   -  jp m,LBL   (sign/negative)

   Operands:
      xh         -  ixh
      xl         -  ixl
      yh         -  iyh
      yl         -  iyl
      [Address]  -  (Address)
      [hl]       -  (hl)
      (ix-6)     -  (ix+-6)

   And pseudo-instructions:
      db         -  defb, defm
      dw         -  defw
      ds         -  defs
      =          -  set
      struct     -  lots of EQUs


LIST OF OTHER KEYWORDS
   ! != $ % & && ( ) * + , - / < << <= = > >= >> [ ] ^ | || ~
   a af af' align b bc c d db de ds dw e end h hl i ix ixh ixl iy iyh
   iyl l label m nc ns nv nz p pe po r s sp struct v xh xl yh yl z 


FILES
   <file>.a80 - source file.
   <file>.z80 - source file -- first alternative.
   <file>.asm - source file -- second alternative.
   <file>.lst - List file.
   <file>.s19 - Motorola S-records output file.
   <file>.hex - Intel hex output file.
   <file>.bin - Binary output file.


BUGS
   No provision for linking other pre-assembled modules is made.
   Escape sequences in strings can't use the \x<digits> and
   \<digits> formats.


RETURNS
   As80 returns one of the following values:

      0 - Source file assembled without errors.
      1 - Incorrect parameter specified on the commandline.
      2 - Unable to open input or output file.
      3 - Assembly gave errors.
      4 - No memory could be allocated.


DIAGNOSTICS
   Help message if only parameter is a question mark, or if an
   illegal option has been specified.


AUTHOR
   This is copyrighted software, but may be distributed freely as long
   as this document accompanies the assembler, and no copyright messages
   are removed.  You are explicitly NOT allowed to sell this software
   for anything more than a reasonable copying fee, say US$5.
   To contact the author:
      Frank A. Vorstenbosch
      Kingswood Software
      P.O. Box 85800              Phone: +31-(70)-355 5241
      2508CM  The Hague           BBS:   +31-(70)-355 8674
      Netherlands                 Email: falstaff@xs4all.nl

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