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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

            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

           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

            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 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

           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

           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:

      #,

   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 

      Align fills zero or more bytes with zeros until the new address

      modulo  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 

      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 

      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 

      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 

   defs 

      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 

   defw 

      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 

      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.

    equ 

      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 

      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 

      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 

      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 

      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 

      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.

    set 

    = 

      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 

   struct ,

      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                 element is one byte

         dw                 element is two bytes

         ds ,   element is the specified number of bytes

         ds           skip the specified number of bytes

         label              element is zero bytes, i.e. set the name

                                  to the current structure offset

         align        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 

      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

   .a80 - source file.

   .z80 - source file -- first alternative.

   .asm - source file -- second alternative.

   .lst - List file.

   .s19 - Motorola S-records output file.

   .hex - Intel hex output 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 and

   \ formats.

RETURNS

   As80 returns one of the following values:

      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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