Directives

Directive Meanings
Output controls
.cpu Select CPU type. Available values are: 8080, 8008, Z80, 6502, 6800, 1802, 6809, 65816
.engine Controls machine type for emulation (only in online ASM80). Available values are: PMI, PMD, JPR, KIM, SBCZ80, SBC6502, SBC09, ZXS and CPM
.pragma sna Makes SNA file instead of HEX (only for Z80)
.pragma tap Makes TAP file instead of HEX (only for Z80)
.pragma prg Makes C64's PRG file instead of HEX (only for 6502) [read more] .PRAGMA PRG ;says “make .PRG instead of .HEX” .ORG $0810 ;or higher .ENT $ ;for “enter here”
.pragma com Makes CP/M COM file instead of HEX (only for Z80/8080) [read more]
.pragma html Makes HTML listing (instead of LST)
.pragma segment Make separate HEX files for cseg, dseg and eseg (without this pragma are all of them in one HEX)
.binfrom addr Starting address for binary download, default is 0. (Only valid for "Download BIN" function in IDE)
.binto addr Last address for binary download (this address WILL NOT BE INCLUDED in binary file) Default is 65536. (Only valid for "Download BIN" function in IDE)
.error message Throws an error during compile phase.
Data definition
db (aliases: defb, fcb) Define Byte. The argument is a comma separated list of string literals or numeric expressions. The string literals are inserted in the object code, and the result of the numeric expression is inserted as a single byte, truncating it if needed. You can use DUP for entering N same values: DB 10 DUP (123) means "10 times value 123"
dw (aliases: defw, fdb) Define Word. The argument is a comma separated list of numeric expressions. Each numeric expression is evaluated as a two byte word and the result inserted in the proper "endianity". You can use DUP for entering N same values: DW 10 DUP (123) means "10 times value 123"
ds (aliases: defm, defs, rmb) Define Space. Take one argument, which is the amount of space to define, in bytes.
fill value, length Fill memory with a value. Take two arguments, the first is a value, the second is length of filled block (byte count).
bsz length(alias: zmb) Fill memory with a given count of zeros.
.cstr When you need write a zero-ended string (C style), you can use DB "Hello",0 - or simple .cstr "Hello"
.pstr Similar as .cstr, but there is no trailing zero. .pstr is a Pascal-style string: first byte is length, then string. So .pstr "Hello" is equal to DB 5, "Hello".
.istr Strings are often defined as simple ASCII, where the last byte has bit 7 set to 1. So .istr "Hello" is the same as DB "Hell","o"+0x80
.include filename Include a file. The file is readed and the result is the same as if the file were copied in the current file instead of the INCLUDE line. The file included may contain INCLUDE directives, and so on. INCLUDE directives are processed before the assembly phases, so the use of IF directives to conditionally include different files is not allowed.
.incbin filename Include a binary file. No parsing, no compiling, just a bunch of DBs.
Code control
org addr ORiGin. Establishes the origin position where to place generated code. Several ORG directives can be used in the same program, but if the result is that code generated overwrites previous, the result is undefined.
.ent addr ENTer point for debugging. I.e. .ent $
.align N The .align directive causes the next data generated to be aligned modulo N bytes.
.phase addr 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.
.dephase End phase block.
Preprocessor
equ (alias: =) EQUate. Must be preceded by a label. The argument must be a numeric expression, the result is assigned to the label. I.e. VIDRAM equ $4000
Conditional blocks
.if cond Contional assembly. The argument must be a numeric expression, a result of 0 is considered as false, any other as true. If the argument is true the following code is assembled until the end of the IF section is encountered, else is ignored. The IF section is ended with a ENDIF directive. IF can't be nested.
.ifn cond IF NOT
.endif End of the IF block
Macros and blocks
.macro macro_name Defines a macro, see the chapter about macros.
.rept count Repeat a block of code substituing arguments. See the chapter about macros.
.endm End of MACRO definition or REPT cycle.
.block Start of logical block. All labels, defined in this block, are local. It means you can’t reference them from outside the block. If you want to define a label globally, simply prefix it with ‘@’, like @LABEL: Good idea is to enclose INCLUDEd code into block.
.endblock End of BLOCK.
Segments
Segments has its own independent ORG pointers, so you can e.g. defined, that data segment begins at 8000h. You can mix data and code together as you need, but assembler keeps code in one chunk, data in another etc.
.cseg Following code is a program (code segment - default)
.dseg Following source code is a data (data segment)
.eseg Following source code belongs to third segment (extended)
.bsseg Following source code is a not-initialized segment. ASM allows only DS and such directives, which does not generate any content
65816 directives
.m8 Accumulator is 8bit
.m16 16bit accumulator
.x8 index register is 8bit
.x16 16bit index

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