From 98b08afee866d4b5d7875ca9177eb75b715d4d2c Mon Sep 17 00:00:00 2001 From: Piotr Fusik Date: Thu, 4 Feb 1999 17:01:22 +0100 Subject: [PATCH] Documentation converted to HTML. --- xasm.htm | 509 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ xasm.txt | 452 ------------------------------------------------ 2 files changed, 509 insertions(+), 452 deletions(-) create mode 100644 xasm.htm delete mode 100644 xasm.txt diff --git a/xasm.htm b/xasm.htm new file mode 100644 index 0000000..3eabe95 --- /dev/null +++ b/xasm.htm @@ -0,0 +1,509 @@ + + +X-Assembler 2.0 Manual + + +
+

X-Assembler version 2.0

+coded by Fox/Taquart +
+
+

INTRODUCTION

+The X-Assembler is an assembler, which generates code for the 6502 processor. +It is 99% compatible with Quick Assembler on 8-bit Atari. +
+

System requirements

+ +
+

Creating a source program

+Source file should be standard text file with IBM-style EOLs: CR/LF. You can +use any text editor on PC to prepare your source code. +Single line of source should not be longer than 256 characters. +There is no limitation on the length of the file. +Source may contain tabulators - there are treated as spaces. +Assembler is NOT case-sensitive. +
+

Converting Quick Assembler files

+You must convert Atari text file into PC text file (EOL's from $9b to $0d/$0a), +ATASCII 0-31 and 128-255 characters should be replaced with standard ASCII +characters, using QAsm expressions.
+You also have to change all OPT directives, but usually you needn't them +at all. +
+

Assembling a source program

+Syntax (parameters in brackets are optional):
+
XASM source [options]
+
'source' is name of source file. +If no extension given, the .ASX is added by default.

+Options are: +

+
/c +
Enable listing false conditionals. +
/i +
Disable listing included source. +
/l[:fname] +
Enable generating listing. If no fname given, listing is written to source.lst. +
/o:fname +
Specify object name. Default is source.obx. +
/s +
Disable converting spaces to tabs. Using tabs makes listing file shorter.
+Tab stops are assumed to be every 8 characters. +
/t[:fname] +
List label table. If no fname given, table is written at the end of listing. +
+ +If source is incorrect, X-Asm displays ONLY FIRST encountered error.

+ +Errorlevels returned by X-Asm:
+3 = bad parameters, assembling not started
+2 = error occured
+1 = warning(s) only
+0 = no errors, no warnings
+ +

Listing structure

+Line of listing includes: + + +

Label table structure

+Line of label table includes: + + +
+

X-ASM LANGUAGE STRUCTURE

+Lines of source code may be: + +Comment lines must have one of the following characters in the FIRST column +of the line: * ; | + +

Numbers

+Numbers are 32-bit signed integers, in the range of -$7fffffff..$7fffffff. +A number can be: + +I think only 'a hardware register' should be explained. It is a short way +of accessing Atari hardware registers:

+^0x means $d00x
+^1x means $d01x
+^2x means $d20x
+^3x means $d30x
+^4x means $d40x
+where x is a hexadecimal digit. + +

Expressions

+Expressions are numbers combined with operators and brackets. +You should use square brackets, because parentheses are reserved +for 6502 indirect addressing. Currently there are 19 operators:

+ ++ Addition
+- Subtraction
+* Multiplication
+/ Division
+% Remainder
+& Bitwise and
+| Bitwise or
+^ Bitwise xor
+<< Arithmetic shift left
+>> Arithmetic shift right
+= Equal
+<> Not equal
+!= Not equal (same as <>)
+< Less than
+> Greater than
+<= Less or equal
+>= Greater or equal
+&& Logical and
+|| Logical or

+ +Operator precedence: +

+first  []
+       * / % & << >>
+       + - | ^
+       = <> != < > <= >=
+       &&
+last   ||
+
+Compare and logical operators assume that zero is false and non-zero is true. +They return -1 for true.

+When calculating expression, 32-bit arithmetic is used. When range of 32 bits +is exceeded, 'Arithmetic overflow' error is generated.

+If result of expression has improper size, 'Value out of range' error occurs.

+Note difference beetwen X-Asm 2.0 and QAsm/X-Asm 1.2: in older assemblers, +which used 16-bit arithmetic, a LDA 0-1 was correct (LDA $ffff), but X-Asm 2.0 +encounters an error: address can't be negative.

+X-Asm recognizes now signed bytes: LDA #-1 is OK. + +

Statements

+A statement is divided into fields: a label field, an operation field, +one or two operand fields, and a comment field. There should be at least +one space between every two fields and there can't be any space within a field +excluding strings. + +

Label field

+This field is optional. It is required only by the EQU directive. +Specyfying this field definies a label. Defined label represents an integer +of range -$ffff..$ffff.

+Name of label must begin in column 1 and can contain letters, digits +and underscores (_). Digit can't be label's first character. Name of label +can be as long as you want and all the characters are meaningful.

+In Quick Assembler only 6 leading characters were recognized +and some programs may not compile well under X-Asm for this reason.

+Defining a label without using EQU makes it equal to current value +of the origin counter. Label can't be redefined. + +

Operation field

+Operation field is the only field which is always required. +You have to put one or more spaces or tab characters between label +and operation field. If no label is defined, line must start with a blank +character. Operation field is always 3 letters long. It can be: +
    +
  1. a 6502 processor command +
  2. a compiler directive +
  3. a pseudo-command +
+
    +
  1. 6502 command
    +One of 56 well known processor commands.

    + +
  2. compiler directive
    +One of the following: +
    +
    EQU - assign a value of expression to the label +
    Note that label represents a number, not a text macro.

    +Examples: +

    five equ 5
+ten  equ five+five
+
    + +
    OPT - set assembling options +
    Currently there are two options: listing generating and headers generating. +You can turn any of these on or off.

    +Examples: +

     opt l-    listing off
+ opt h-    headers off
+ opt l+h-  listing on, headers off
+
    +Remember not to put a space between options: +
     opt l+ h-
+
    +is actually +
     opt l+
+
    +because h- is a comment.

    +Default (if no opt specified) is opt l+h+.

    + +

    ORG - set new origin counter +
    Examples: +
     org $600         code will be located starting from $0600
+table org *+100   'table' points to 100 bytes of uninitialized data
+
    +New! You can set some options applied to new header (if headers are on): +
     org $600
+ rts
+ org a:$601
+
    +'a:' tells X-Asm to always make a header, even it is unnecessary (as in above). +So by default X-Asm 2.0 does not generate unnecessary headers, distinct from +QAsm and X-Asm 1.2. +
     org f:$700
+
    +'f:' works same as 'a:', but additionally tells to generate a $ff,$ff prefix +before header. X-Asm adds it to the first header in file by default, so use +this option only if you want the $ff's somewhere inside.

    + +

    DTA - define data +
    You may define: +
      +
    • numbers +
        +
      • bytes: b(200) +
      • words: a(10000) +
      • low bytes of words: l(511) defines byte 255 +
      • high bytes of words: h(511) defines byte 1 + You may enter many expressions in parentheses and combine different types + of data in single line.

        + You may also define a sinus table. Enter this expression:
        + sin(centre,amp,size,first,last)
        + where: +

          +
        • centre is a number which is added to every value of sinus +
        • amp is the amplitude of sinus +
        • size is the period of sinus +
        • first,last define range of values in the table. + They are optional. Default are 0,size-1. +
        + Example: dta a(sin(0,1000,256,0,63)) defines table of 64 words representing + a quarter of sinus with amplitude of 1000. +
      • real numbers: r(-1.23456e12)
        + Real numbers are written in 6-byte Atari Floating-Point format. You can't + combine reals with operators, as you can integers.

        +

      +
    • text strings +
        +
      • ASCII strings: c'Text' or c"Text" +
      • ANTIC strings: d'Text' or d"It's something new!" +
      + A character string consists of any of characters surrounded by quotation + marks. Within a string, a single quotation mark character is + represented by two succesive quotation marks.

      + Placing a '*' character after a string inverts bit 7 in every byte of string.

      +

    +Examples of DTA: +
    + dta b(2,5),a(1000,-1),l(12345,sin(0,127,256))
+ dta d"ANTIC"*,c'It''s a string',b(155)
+
    + +
    ICL - include another source file +
    Specifies another file to be included in the assembly as if the contests of +the referenced file appeared in place of the ICL statement. The included file +may contain other ICL statements.

    +Examples: +

    + icl 'macros.asx'
+ icl 'c:\atari\xasm\fileio.asx'
+
    + +
    END - end assembling of file +
    Remaining part of the file is not assembled. If this statement does not occur, +assembler stops assembling when encounters end of file.
    +Example: +
    + end
+
    + +
    INS - insert contents of file +
    Copies every byte of specified file into object file and moves origin counter, +as if these bytes were defined with DTA.

    +Examples: +

    + ins 'picture.raw'
+ ins 'tables.dat'
+
    +New! You may specify range of inserted file. Syntax is: +
    + ins 'file'[,offset[,length]]
+
    +First byte in file has offset 0.

    +If offset is negative, it is counted from the end of file. +

    + ins 'file',-256   inserts last 256 bytes of file
+ ins 'file',10,10  inserts bytes 10..19 of file
+
    + +
    RUN - generate run address +
    The Atari executable program should have run address specified. Remember that +a program may be loaded in many areas of memory and started from any address. +
     run addr
+
    +is equivalent to: +
     org $2e0
+ dta a(addr)
+
    +Examples: +
     run start
+ run program
+
    + +
    INI - generate init address +
    The Atari executable program may have some routines which are executed during +loading process. There may be many init blocks in one file. +Examples: +
     ini init
+ ini showpic
+
    + +
    ERT - generate error if expression is true +
    Examples: +
     ert *>$c000
+ ert len1>$ff||len2>$ff
+
    + +
    IFT - assemble if expression is true
    +ELS - else
    +EIF - end if
    +
    Example: +
    noscr equ 1
+ ift noscr
+ lda #0
+ els
+ lda #$22
+ eif
+ sta $22f
+
    + +
    +
  3. pseudo-command
    +It is something like built-in macro. It replaces two or more standard +processor commands. Note that it is not an illegal instruction and works +on typical 6502. +
    +
    ADD - addition without carry +
    If you ever programmed 6502, you must have noticed that you had to use a CLC +before ADC for every simple addition.
    +X-Asm can do it for you. ADD simply replaces two instructions: CLC and ADC.

    + +

    SUB - subtraction +
    It is SEC and SBC.

    + +

    JNE, JEQ, JCC, JCS, JPL, JMI, JVC, JVS - conditional jumps +
    They are a kind of 'long' branches. While standard branches (BNE, BEQ) have +range of -128..+127, these jumps have range of all 64 kB.

    +For example: a JNE DEST is replaced with: +

     beq *+5
+ jmp dest
+
    + +
    INW - increment word +
    It is a 16-bit memory increment command. An INW DEST will be replaced by: +
     inc dest
+ bne _skip
+ inc dest+1
+_skip equ *
+
    +The _skip label is not declared of course.

    + +

    MVA, MVX, MVY - move byte using accumulator, X or Y +
    These pseudo-commands require two operands. +
     mva source dest = lda source : sta dest
+ mvx source dest = ldx source : stx dest
+ mvy source dest = ldy source : sty dest
+
    + +
    MWA, MWX, MWY - move word using accumulator, X or Y +
    Also require two operands. They are something like combination of two MV*'s: +one to move low byte, and the other to move high byte.

    +You can't use indirect nor pseudo addressing modes with MW*.

    +Destination must be absolute address (indexed or not).

    +When source is also absolute, a MW* SOURCE DEST will be: +

     mv* source   dest
+ mv* source+1 dest+1
+
    +When source is immediate, a MW* #IMMED dest will be +
     mv* <immed dest
+ mv* >immed dest+1
+
    +but when <IMMED = >IMMED and IMMED is not forward-referenced, +X-Asm uses optimization: +
     mv* <immed dest
+ st* dest+1
+
    +
    +
+ +

Operand

+It depends on the operation field. Some statements don't need an operand +or need two operands.

+ +6502 commands require operand depending on the addressing mode. +Addressing modes should be entered in standard convention except +the accumulator addressing mode, which should be marked with a @ character +(as in Quick Assembler).

+ +There are two extra immediate addressing modes: < and >, which use low/high +byte of word is used rather than byte value.

+ +In absolute addressing modes, X-Asm examines expression and uses zero-page +addressing mode if it thinks it is possible to do it. You may override it +with a: and z: prefixes.

+ +Examples: +

+ nop
+ asl @
+ lda >$1234	assembles to lda #$12
+ lda $100,x
+ lda a:0	generates 16-bit address
+ jmp ($0a)
+ lda ($80),y
+
+ +New! X-Asm 2.0 brings pseudo addressing modes. They are similar to +pseudo-commands and you may use them as standard addressing modes +in all 6502 commands and pseudo-commands, excluding MW*: +
 cmd a,x+    =  cmd a,x   : inx
+ cmd a,x-    =  cmd a,x   : dex
+ cmd a,y+    =  cmd a,y   : iny
+ cmd a,y-    =  cmd a,y   : dey
+ cmd (z),y+  =  cmd (z),y : iny
+ cmd (z),y-  =  cmd (z),y : dey
+ cmd (z,0)   =  ldx #0    : cmd (z,x)
+ cmd (z),0   =  ldy #0    : cmd (z),y
+
+

Problems

+These notes may help you solve problems: + + + \ No newline at end of file diff --git a/xasm.txt b/xasm.txt deleted file mode 100644 index 859e821..0000000 --- a/xasm.txt +++ /dev/null @@ -1,452 +0,0 @@ -X-Assembler version 2.0 -======================= -coded by Fox/Taquart - -INTRODUCTION -============ -The X-Assembler is an assembler, which generates code for the 6502 processor. -It is 99% compatible with Quick Assembler on 8-bit Atari. - -System requirements -------------------- -- a PC compatible computer with 386 or better CPU -- a MS-DOS compatible OS -- a numeric coprocessor for generating sinus tables - Your CPU probably has a built-in coprocessor. - -Creating a source program -------------------------- -Source file should be standard text file with IBM-style EOLs: CR/LF. You can -use any text editor on PC to prepare your source code. -Single line of source should not be longer than 256 characters. -There is no limitation on the length of the file. -Source may contain tabulators - there are treated as spaces. -Assembler is NOT case-sensitive. - -Converting Quick Assembler files --------------------------------- -You must convert Atari text file into PC text file (EOL's from $9b to $0d/$0a), -ATASCII 0-31 and 128-255 characters should be replaced with standard ASCII -characters, using QAsm expressions. -You also have to change all OPT directives, but usually you needn't them -at all. - -Assembling a source program ---------------------------- -Syntax (parameters in brackets are optional): -XASM source [options] -'source' is name of source file. -If no extension given, the .ASX is added by default. -Options are: -/c -Enable listing false conditionals. -/i -Disable listing included source. -/l[:fname] -Enable generating listing. If no fname given, listing is written to source.lst. -/o:fname -Specify object name. Default is source.obx. -/s -Disable converting spaces to tabs. Using tabs makes listing file shorter. -Tab stops are assumed to be every 8 characters. -/t[:fname] -List label table. If no fname given, table is written at the end of listing. - -If source is incorrect, X-Asm displays ONLY FIRST encountered error. - -Errorlevels returned by X-Asm: -3 = bad parameters, assembling not started -2 = error occured -1 = warning(s) only -0 = no errors, no warnings - -Listing structure ------------------ -Line of listing includes: -- decimal number of line of source file (if source is different than in -previous listed line, appropriate message line is generated) -- hexadecimal origin -- hexadecimal bytes written to object file -Listed are also generated headers. A 'xxxx-yyyy>' in place of origin is -a generated header: $xxxx is the first and $yyyy is the last byte of block. -A 'FFFF>' represents two $ff bytes written as a header prefix. -A plus sign placed after hex numbers stands for more bytes written to object -in this line, not listed through lack of space. -- remaining part of listing line is a copy of source - -Label table structure ---------------------- -Line of label table includes: -- some info of label: - n - label not used - 2 - label value known in pass 2 only (label definition uses forward reference - and thus you can't do forward references to that label) -- hex value of label -- name of label - -X-ASM LANGUAGE STRUCTURE -======================== -Lines of source code may be: -- empty lines - ignored, of course -- comments - ignored, too -- statements - not ignored :-) -Comment lines must have one of the following characters in the FIRST column -of the line: * ; | - -Numbers -------- -Numbers are 32-bit signed integers, in the range of -$7fffffff..$7fffffff. -A number can be: -- a decimal number -12345 -- a hexadedecimal number $abcd -- a binary number %10100101 -- a character 'a' or "a" (new in 2.0!) -- a hardware register ^31 -- an origin counter * -I think only 'a hardware register' should be explained. It is a short way -of accessing Atari hardware registers: -^0x means $d00x -^1x means $d01x -^2x means $d20x -^3x means $d30x -^4x means $d40x -where x is a hexadecimal digit. - -Expressions ------------ -Expressions are numbers combined with operators and brackets. -You should use square brackets, because parentheses are reserved -for 6502 indirect addressing. Currently there are 19 operators: - -+ Addition -- Subtraction -* Multiplication -/ Division -% Remainder -& Bitwise and -| Bitwise or -^ Bitwise xor -<< Arithmetic shift left ->> Arithmetic shift right -= Equal -<> Not equal -!= Not equal (same as <>) -< Less than -> Greater than -<= Less or equal ->= Greater or equal -&& Logical and -|| Logical or - -Operator precedence: -first [] - * / % & << >> - + - | ^ - = <> != < > <= >= - && -last || - -Compare and logical operators assume that zero is false and non-zero is true. -They return -1 for true. -When calculating expression, 32-bit arithmetic is used. When range of 32 bits -is exceeded, 'Arithmetic overflow' error is generated. -If result of expression has improper size, 'Value out of range' error occurs. -Note difference beetwen X-Asm 2.0 and QAsm/X-Asm 1.2: in older assemblers, -which used 16-bit arithmetic, a LDA 0-1 was correct (LDA $ffff), but X-Asm 2.0 -encounters an error: address can't be negative. -X-Asm recognizes now signed bytes: LDA #-1 is OK. - -Statements ----------- -A statement is divided into fields: a label field, an operation field, -one or two operand fields, and a comment field. There should be at least -one space between every two fields and there can't be any space within a field -excluding strings. - -Label field -~~~~~~~~~~~ -This field is optional. It is required only by the EQU directive. -Specyfying this field definies a label. Defined label represents an integer -of range -$ffff..$ffff. -Name of label must begin in column 1 and can contain letters, digits -and underscores (_). Digit can't be label's first character. Name of label -can be as long as you want and all the characters are meaningful. -In Quick Assembler only 6 leading characters were recognized -and some programs may not compile well under X-Asm for this reason. -Defining a label without using EQU makes it equal to current value -of the origin counter. Label can't be redefined. - -Operation field -~~~~~~~~~~~~~~~ -Operation field is the only field which is always required. -You have to put one or more spaces or tab characters between label -and operation field. If no label is defined, line must start with a blank -character. Operation field is always 3 letters long. It can be: -a. a 6502 processor command -b. a compiler directive -c. a pseudo-command - -a. 6502 command -One of 56 well known processor commands. - -b. compiler directive -One of the following: - -EQU - assign a value of expression to the label -Note that label represents a number, not a text macro. -Examples: -five equ 5 -ten equ five+five - -OPT - set assembling options -Currently there are two options: listing generating and headers generating. -You can turn any of these on or off. -Examples: - opt l- listing off - opt h- headers off - opt l+h- listing on, headers off -Remember not to put a space between options: - opt l+ h- -is actually - opt l+ -because h- is a comment. -Default (if no opt specified) is opt l+h+. - -ORG - set new origin counter -Examples: - org $600 code will be located starting from $0600 -table org *+100 'table' points to 100 bytes of uninitialized data -New! You can set some options applied to new header (if headers are on): - org $600 - rts - org a:$601 -'a:' tells X-Asm to always make a header, even it is unnecessary (as in above). -So by default X-Asm 2.0 does not generate unnecessary headers, distinct from -QAsm and X-Asm 1.2. - org f:$700 -'f:' works same as 'a:', but additionally tells to generate a $ff,$ff prefix -before header. X-Asm adds it to the first header in file by default, so use -this option only if you want the $ff's somewhere inside. - -DTA - define data -You may define: -* numbers - - bytes: b(200) - - words: a(10000) - - low bytes of words: l(511) defines byte 255 - - high bytes of words: h(511) defines byte 1 - You may enter many expressions in parentheses and combine different types - of data in single line. - You may also define a sinus table. Enter this expression: - sin(centre,amp,size,first,last) - where: - - centre is a number which is added to every value of sinus - - amp is the amplitude of sinus - - size is the period of sinus - - first,last define range of values in the table. - They are optional. Default are 0,size-1. - Example: dta a(sin(0,1000,256,0,63)) defines table of 64 words representing - a quarter of sinus with amplitude of 1000. - - real numbers: r(-1.23456e12) - Real numbers are written in 6-byte Atari Floating-Point format. You can't - combine reals with operators, as you can integers. -* text strings - - ASCII strings: c'Text' or c"Text" - - ANTIC strings: d'Text' or d"It's something new!" - A character string consists of any of characters surrounded by quotation - marks. Within a string, a single quotation mark character is - represented by two succesive quotation marks. - Placing a '*' character after a string inverts bit 7 in every byte of string. -Examples of DTA: - dta b(2,5),a(1000,-1),l(12345,sin(0,127,256)) - dta d"ANTIC"*,c'It''s a string',b(155) - -ICL - include another source file -Specifies another file to be included in the assembly as if the contests of -the referenced file appeared in place of the ICL statement. The included file -may contain other ICL statements. -Examples: - icl 'macros.asx' - icl 'c:\atari\xasm\fileio.asx' - -END - end assembling of file -Remaining part of the file is not assembled. If this statement does not occur, -assembler stops assembling when encounters end of file. -Example: - end - -INS - insert contents of file -Copies every byte of specified file into object file and moves origin counter, -as if these bytes were defined with DTA. -Examples: - ins 'picture.raw' - ins 'tables.dat' -New! You may specify range of inserted file. Syntax is: - ins 'file'[,offset[,length]] -First byte in file has offset 0. -If offset is negative, it is counted from the end of file. - ins 'file',-256 inserts last 256 bytes of file - ins 'file',10,10 inserts bytes 10..19 of file - -RUN - generate run address -The Atari executable program should have run address specified. Remember that -a program may be loaded in many areas of memory and started from any address. - run addr -is equivalent to: - org $2e0 - dta a(addr) -Examples: - run start - run program - -INI - generate init address -The Atari executable program may have some routines which are executed during -loading process. There may be many init blocks in one file. -Examples: - ini init - ini showpic - -ERT - generate error if expression is true -Examples: - ert *>$c000 - ert len1>$ff||len2>$ff - -IFT - assemble if expression is true -ELS - else -EIF - end if -Example: -noscr equ 1 - ift noscr - lda #0 - els - lda #$22 - eif - sta $22f - -c. pseudo-command -It is something like built-in macro. It replaces two or more standard -processor commands. Note that it is not an illegal instruction and works -on typical 6502. - -ADD - addition without carry -If you ever programmed 6502, you must have noticed that you had to use a CLC -before ADC for every simple addition. -X-Asm can do it for you. ADD simply replaces two instructions: CLC and ADC. - -SUB - subtraction -It is SEC and SBC. - -JNE, JEQ, JCC, JCS, JPL, JMI, JVC, JVS - conditional jumps -They are a kind of 'long' branches. While standard branches (BNE, BEQ) have -range of -128..+127, these jumps have range of all 64 kB. -For example: a JNE DEST is replaced with: - beq *+5 - jmp dest - -INW - increment word -It is a 16-bit memory increment command. An INW DEST will be replaced by: - inc dest - bne _skip - inc dest+1 -_skip equ * -The '_skip' label is not declared of course. - -MVA, MVX, MVY - move byte using accumulator, X or Y -These pseudo-commands require two operands. - mva source dest = lda source : sta dest - mvx source dest = ldx source : stx dest - mvy source dest = ldy source : sty dest - -MWA, MWX, MWY - move word using accumulator, X or Y -Also require two operands. They are something like combination of two MV*'s: -one to move low byte, and the other to move high byte. -You can't use indirect nor pseudo addressing modes with MW*. -Destination must be absolute address (indexed or not). -When source is also absolute, a MW* SOURCE DEST will be: - mv* source dest - mv* source+1 dest+1 -When source is immediate, a MW* #IMMED dest will be - mv* immed dest+1 -but when IMMED and IMMED is not forward-referenced, -X-Asm uses optimization: - mv* , which use low/high -byte of word is used rather than byte value. - -In absolute addressing modes, X-Asm examines expression and uses zero-page -addressing mode if it thinks it is possible to do it. You may override it -with 'a:' and 'z:' prefixes. - -Examples: - nop - asl @ - lda >$1234 assembles to lda #$12 - lda $100,x - lda a:0 generates 16-bit address - jmp ($0a) - lda ($80),y - -New! X-Asm 2.0 brings pseudo addressing modes. They are similar to -pseudo-commands and you may use them as standard addressing modes -in all 6502 commands and pseudo-commands, excluding MW*: - cmd a,x+ = cmd a,x : inx - cmd a,x- = cmd a,x : dex - cmd a,y+ = cmd a,y : iny - cmd a,y- = cmd a,y : dey - cmd (z),y+ = cmd (z),y : iny - cmd (z),y- = cmd (z),y : dey - cmd (z,0) = ldx #0 : cmd (z,x) - cmd (z),0 = ldy #0 : cmd (z),y - -Problems --------- -These notes may help you solve problems: - -* No spaces are allowed within a field. -label equ 1 + 2 -causes label to be equal 1 ('+ 2' is treated as a comment). - -* < and > represent addressing modes rather than LOW and HIGH operators. -You specify 'lda