Version 1.6 instructions
------------------------

Command line syntax:

    asm6502 [options] srcfile

Valid options:

    --             End of options (sometimes needed after -l or -o)
    -l [filename]  Make a listing file, default is srcfile.lst
    -o [filename]  Output object code to file, default is srcfile.hex
    -e             Show errors to screen
	-w             Show warnings to screen

The data pseudo-ops are:

DB/FCB/BYTE/DC.B - one or more bytes, including strings in quotes
DW/FDB/WORD/DC.W - one or more words
DS/RMB/BLKB/DC.S - skip specified number of bytes
FCC              - Motorola-style string constant; surround string with
                   '/' characters

EQU or '=' sets a label equal to a constant, and SET does the same thing,
except you can re-define the value multiple times through the code.  Labels
starting with an "@" such as "@1" append the @ label to the last non-@
label encountered, and work as temporary labels.

ORG starts assembling at a new address.  RORG continues generating code at
the current address, but changes the PC.  This lets you assemble code that
will be copied to and executed at a different address.

Comments begin with a semicolon (";") anywhere in the line or with an
asterisk ("*") at the beginning of a line.


Expressions:

The current PC is referred to by using "." or "*".
Binary numbers are prefixed with '%', and hex numbers with '$'.
Character values are surrounded with a pair of single quotes ("'x'").
Binary numbers are postfixed with 'B', octal with 'O', decimal
with 'D', and hex with 'H'.  Hexadecimal values don't need a
leading zero.

- val        negative of val
+ val        positive of val
~ val        bitwise not of val
< val        low 8 bits of val
> val        high 8 bits of val

x * y        x multiplied by y
x / y        x divided by y
x % y        x modulo y
x + y        x plus y
x - y        x minus y
x << y		 x shifted left by y bits
x >> y       x shifted right by y bits
x & y        bitwise x and y
x | y        bitwise x or y


 - - -

Version 1.1 changes:

* Fixed a bug that would prevent using any label beginning with the letter
  'A' as the first parameter of an opcode.

* Prevented output of unnecessary origin commands to .DAT file to avoid
  complaints from MAKEROM.

* Fixed the "data overwritten" error in MAKEROM, which was only displaying
  the low byte of the offending address.

* Improved MAKEROM's handling of out-of-range memory addresses.

* Added a basic macro feature, controlled by the following pseudo-ops:

    <label>  MACRO         start recording the macro with the name <label>
             ENDM          end the macro
             LIST MACRO    enable macro expansion in listings
             LIST NOMACRO  disable macro expansion in listings (default)
             <label>       use the macro

  Note that macros can not currently call other macros.

 - - -

Version 1.2 changes

* Added macro parameters

* Added FCB, FDB, RMB, BYTE, WORD, and BLKB pseudo-ops

* Added binary constants (xxxxxxxxB and %xxxxxxxx)

* Added ASLA, ROLA, LSRA, and RORA opcodes

* Added '$' by itself as the current location, in addition to '.' and '*'

* DB and DW opcodes now work properly with multiple operands

* Added &, |, <<, and >> to expression evaluator.  Each of these operators
  has the same precedence, below + and -.

* Default file extension was changed from .A65 to .ASM

* Allowed command line options to be specified in lowercase

* Added a new RORG "relative ORG" pseudo-op to allow assembling code that
  will later be moved to a different address

 - - -

Version 1.3 changes

* No more than one macro could be defined, because the macro list wasn't
  being linked properly.

* Errorlevel 1 is now returned if any errors occurred during assembly.

 - - -

Version 1.4 changes

* Added FCC pseudo-op

* Lines beginning with "*" are now comments

* Jump indirect wouldn't work correctly if the line had a comment

* No error was generated if too many macro parameters were used

* Maximum macro parameters increased from 5 to 10

* Lines from macro expansions with errors are now displayed

* Symbol table is now displayed with more than one column

* Lines that generate more than 3 bytes are flagged with a "+"

 - - -
 
Version 1.5 changes

* Converted from Pascal to C.

* Added 65C02 opcodes.  They can be disabled at compile time with a #define.

* Improved output with more than 3 bytes of object code from a line.

* Now outputs code in Intel Hex format.  Old object format still available
  by changing a #define.

 - - -

Version 1.6 changes

* Separated common code so that my Z-80 assembler could use the new features like
  macros and INCLUDE.

* Fixed a bug that would cause phase errors with one-character label names.

* Fixed a bug that would prevent control pseudo-ops from working after END pseudo-op

* Added DC.B, DC.W, .BYTE, and .WORD pseudo-ops for compatibility with source code
  written for various other assemblers.

* DB now handles double quotes, \r \n \t \' and \".  A bug in the handlng of paired
  quotes ("foo""bar") fixed.

* new DRW pseudo-op to do a DW in reverse order (such as for Atari 7800 Maria
  chip programming)

* added INCLUDE pseudo-op.  Maximum nesting level is set to 10 by a #define.

* added PROCESSOR 6502/PROCESSOR 65C02 pseudo-op to select 65C02 instructions, and
  for improved DASM compatiblity.

* increased the size of bytStr[] from 256 to 1024 bytes.  This will allow more data
  for long-data pseudo-ops like DB, etc.

* added support for DS pseudo-op with an initializer.  This is currently limited to
  a max of 1024 bytes.  (DB, DW, and FCC also have this limit, but do not yet have a
  bounds check for it)

* added HEX pseudo-op.  This also currently limited to a max of 1024 bytes.

* [ and ] can now be used as parentheses in expressions, for better DASM source
  compatibility.

* REND pseudo-op added for better DASM source compatibility.  Note that a label on
  the REND line will receive the relocated value of the current code location.

Known bugs in version 1.6:

  DB, DW, and FCC pseudo-ops have a limit of 1024 bytes, but do not bounds-check
  for it.  If you really need them longer than this on a single source line, change
  the #define for MAX_BYTSTR.

 - - -

Stuff to do:

* Bounds checking for DB, DW, FCC pseudo-ops.  Setting MAX_BYTSTR to 65536 would be
  a bit drastic, but would effectively solve the problem.

* 8080/8085 opcodes for Z-80 assembler

* Conditional assembly pseudo-ops would be nice.

* "FCC n,TEXT" mode.  This is an obscure format of Motorola's FCC pseudo-op that I
  should implement for completeness.