## AS6801 Assembler

####

    .hd6303 DIRECTIVE

    Format:

            .hd6303

    The  .hd6303 directive enables processing of the HD6303 specific
    mnemonics not included in  the  6801  instruction  set.   HD6303
    mnemonics  encountered  without  the  .hd6303  directive will be
    flagged with an <o> error.

    6801 REGISTER SET

    The following is a list of the 6801 registers used by AS6801:

            a,b     -       8-bit accumulators
            d       -       16-bit accumulator <a:b>
            x       -       index register

    6801 INSTRUCTION SET

       The  following tables list all 6801/6303 mnemonics recognized
    by the AS6801 assembler.  The designation []  refers  to  a  re-
    quired  addressing  mode argument.  The following list specifies
    the format for each addressing mode supported by AS6801:

            #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

            ext             extended addressing

            label           branch label

    The  terms  data, dir, offset, ext, and label may all be expres-
    sions.

       Note  that  not all addressing modes are valid with every in-
    struction, refer to  the  6801/6303  technical  data  for  valid
    modes.

    Inherent Instructions

            aba             abx
            cba             clc
            cli             clv
            daa             des
            dex             ins
            inx             mul
            nop             rti
            rts             sba
            sec             sei
            sev             swi
            tab             tap
            tba             tpa
            tsx             txs
            wai

    Branch Instructions

            bra     label           brn     label
            bhi     label           bls     label
            bcc     label           bhs     label
            bcs     label           blo     label
            bne     label           beq     label
            bvc     label           bvs     label
            bpl     label           bmi     label
            bge     label           blt     label
            bgt     label           ble     label
            bsr     label

    Single Operand Instructions

            asla            aslb            asld
            asl a           asl b           asl d
            asl     []

            asra            asrb
            asr a           asr b
            asr     []

            clra            clrb
            clr a           clr b
            clr     []

            coma            comb
            com a           com b
            com     []

            deca            decb
            dec a           dec b
            dec     []

            eora            eorb
            eor a           eor b
            eor     []

            inca            incb
            inc a           inc b
            inc     []

            lsla            lslb            lsld
            lsl a           lsl b           lsl d
            lsl     []

            lsra            lsrb            lsrd
            lsr a           lsr b           lsr d
            lsr     []

            nega            negb
            neg a           neg b
            neg     []

            psha            pshb            pshx
            psh a           psh b           psh x

            pula            pulb            pulx
            pul a           pul b           pul x

            rola            rolb
            rol a           rol b
            rol     []

            rora            rorb
            ror a           ror b
            ror     []

            tsta            tstb
            tst a           tst b
            tst     []

    Double Operand Instructions

            adca    []      adcb    []
            adc a   []      adc b   []

            adda    []      addb    []      addd    []
            add a   []      add b   []      add d   []

            anda    []      andb    []
            and a   []      and b   []

            bita    []      bitb    []
            bit a   []      bit b   []

            cmpa    []      cmpb    []
            cmp a   []      cmp b   []

            ldaa    []      ldab    []
            lda a   []      lda b   []

            oraa    []      orab    []
            ora a   []      ora b   []

            sbca    []      sbcb    []
            sbc a   []      sbc b   []

            staa    []      stab    []
            sta a   []      sta b   []

            suba    []      subb    []      subd    []
            sub a   []      sub b   []      sub d   []

    Jump and Jump to Subroutine Instructions

            jmp     []      jsr     []

    Long Register Instructions

            cpx     []      ldd     []
            lds     []      ldx     []
            std     []      sts     []
            stx     []

    6303 Specific Instructions

            aim     #data, []       eim     #data, []
            oim     #data, []       tim     #data, []

            xgdx            slp

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###### Last Updated: March 2025