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AS6804 Assembler


   Requires the .setdp directive to specify the ram area.  


6804 REGISTER SET 

The following is a list of the 6804 registers used by AS6804:  

        x,y     -       index registers


6804 INSTRUCTION SET 


   The  following  tables  list all 6804 mnemonics recognized by
the AS6804 assembler.  The designation [] refers to  a  required
addressing  mode  argument.   The  following  list specifies the
format for each addressing mode supported by AS6804:  

        #data           immediate data
                        byte or word data

        ,x              register indirect addressing

        dir             direct addressing
                        (see .setdp directive)
                        0 <= dir <= 255

        ext             extended addressing

        label           branch label

The  terms data, dir, and ext may be expressions.  The label for
the short branchs beq, bne, bcc, and bcs must not be external.  

   Note  that  not all addressing modes are valid with every in-
struction, refer to the 6804 technical data for valid modes.  


Inherent Instructions 

        coma            decx
        decy            incx
        incy            rola
        rti             rts
        stop            tax
        tay             txa
        tya             wait


Branch Instructions 

        bne     label           beq     label
        bcc     label           bcs     label


Single Operand Instructions 

        add     []
        and     []
        cmp     []
        dec     []
        inc     []
        lda     []
        sta     []
        sub     []


Jump and Jump to Subroutine Instructions 

        jsr     []
        jmp     []


Bit Test Instructions 

        brclr   #data,[],label
        brset   #data,[],label

        bclr    #label,[]
        bset    #label,[]


Load Immediate data Instruction 

        mvi     [],#data


6804 Derived Instructions 

        asla
        bam     label
        bap     label
        bxmi    label
        bxpl    label
        bymi    label
        bypl    label
        clra
        clrx
        clry
        deca
        decx
        decy
        inca
        incx
        incy
        ldxi    #data
        ldyi    #data
        nop
        tax
        tay
        txa
        tya

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Last Updated: April 2009