## AS6805 Assembler

####

    .6805 DIRECTIVE

    Format:

            .6805

    The  .6805  directive  selects  the MC6805 specific cycles count
    output when the -c command line option is specified.

    .hc05 DIRECTIVE

    Format:

            .hc05

    The  .hc05 directive selects the MC68HC05/146805 specific cycles
    count output when the -c command line option is specified.

    THE .__.CPU.  VARIABLE

       The value of the pre-defined symbol '.__.CPU.' corresponds to
    the selected processor type.  The default value is 0 which  cor-
    responds  to  the  default  processor type.  The following table
    lists the processor types and associated values  for  the  ASZ80
    assembler:

            Processor Type            .__.CPU. Value
            --------------            --------------
                .6805                        0
                .hc05                        1

       The  variable  '.__.CPU.'  is by default defined as local and
    will not be output to the created .rel file.  The assembler com-
    mand line options -g or -a will not cause the local symbol to be
    output to the created .rel file.

       The  assembler  .globl  directive  may  be used to change the
    variable type to global causing its definition to be  output  to
    the  .rel file.  The inclusion of the definition of the variable
    '.__.CPU.' might be a useful means of validating that seperately
    assembled  files have been compiled for the same processor type.
    The linker will report an error for variables with multiple  non
    equal definitions.

    6805 REGISTER SET

    The following is a list of the 6805 registers used by AS6805:

            a       -       8-bit accumulator
            x       -       index register

    6805 INSTRUCTION SET

       The  following  tables  list all 6805 mnemonics recognized by
    the AS6805 assembler.  The designation [] refers to  a  required
    addressing  mode  argument.   The  following  list specifies the
    format for each addressing mode supported by AS6805:

            #data           immediate data
                            byte or word data

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

            ,x              register indirect addressing
                            zero offset

            offset,x        register indirect addressing
                              0 <= offset <= 255   --- byte mode
                            256 <= offset <= 65535 --- word mode
                            (an externally defined offset uses the
                             word mode)

            ext             extended addressing

            label           branch label

    The terms data, dir, offset, and ext may all be expressions.

       Note  that  not all addressing modes are valid with every in-
    struction, refer to the 6805 technical data for valid modes.

    Control Instructions

            clc             cli
            nop             rsp
            rti             rts
            sec             sei
            stop            swi
            tax             txa
            wait

    Bit Manipulation Instructions

            brset   #data,*dir,label
            brclr   #data,*dir,label

            bset    #data,*dir
            bclr    #data,*dir

    Branch Instructions

            bra     label           brn     label
            bhi     label           bls     label
            bcc     label           bcs     label
            bne     label           beq     label
            bhcc    label           bhcs    label
            bpl     label           bmi     label
            bmc     label           bms     label
            bil     label           bih     label
            bsr     label

    Read-Modify-Write Instructions

            nega            negx
            neg     []

            coma            comx
            com     []

            lsra            lsrx
            lsr     []

            rora            rorx
            ror     []

            asra            asrx
            asr     []

            lsla            lslx
            lsl     []

            rola            rolx
            rol     []

            deca            decx
            dec     []

            inca            incx
            inc     []

            tsta            tstx
            tst     []

            clra            clrx
            clr     []

    Register\Memory Instructions

            sub     []              cmp     []
            sbc     []              cpx     []
            and     []              bit     []
            lda     []              sta     []
            eor     []              adc     []
            ora     []              add     []
            ldx     []              stx     []

    Jump and Jump to Subroutine Instructions

            jmp     []              jsr     []

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###### Last Updated: March 2025