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ASST7 Assembler

ST7 REGISTER SET 

The following is a list of the ST7 registers used by ASST7:  

        a       -       8-bit accumulator
        x,y     -       8-bit index registers
        cc      -       8-bit condition code register
        s       -       16-bit stack pointer


ST7 INSTRUCTION SET 


     The following list specifies the format for each addressing
mode supported by ASST7:  

        reg             register addressing
                        (a,x,y,s,cc)

        #data           immediate data byte

        *saddr          8-bit zero page addressing
                        0x00 <= dir <= 0xFF

        laddr           16-bit addressing

        (x)             register indirect addressing

        (*sofst,r)      short indexed (r = x,y)
        (sofst,r).b

        (lofst,r).w     long indexed (r = x,y)

        (ofst,r)        if ofst is relocatable or
                        an external value then
                        the (lofst,r).w mode is
                        selected by default
                        else

        (ofst,r)        if ofst is a locally
                        defined constant then
                        the (sofst,r).b mode
                        is selected when
                        0x00 <= ofst <= 0xFF else
                        the (lofst,r).w mode
                        is selected

                        Instructions supporting
                        only a single form will
                        use the appropriate form
                        but will report an error.


        [*saddr]        short indirect
        [saddr].b

        [laddr].w       long indexed

        [addr]          if addr is relocatable or
                        an external value then
                        the [laddr].w mode is
                        selected by default
                        else

        [addr]          if addr is a locally
                        defined constant then
                        the [saddr].b mode
                        is selected when
                        0x00 <= addr <= 0xFF else
                        the [laddr].w mode
                        is selected

                        Instructions supporting
                        only a single form will
                        use the appropriate form
                        but will report an error.


        ([*saddr],r)    short indirect indexed
        ([saddr].b,r)   (r = x,y)
        ([saddr],r).b

        ([laddr].w,r)   long indirect indexed
        ([laddr],r).w   (r = x,y)

        ([addr],r)      if addr is relocatable or
                        an external value then
                        the ([laddr],r).w mode is
                        selected by default
                        else

        ([addr],r)      if addr is a locally
                        defined constant then
                        the ([saddr],r).b mode
                        is selected when
                        0x00 <= addr <= 0xFF else
                        the ([laddr],r).w mode
                        is selected

                        Instructions supporting
                        only a single form will
                        use the appropriate form
                        but will report an error.


        label           pc-relative branch addressing



The  terms  data,  saddr,  laddr,  addr, sofst, lofst, ofst, and
label may all be expressions.  

     Note that not all addressing modes are valid with every in-
struction, refer to the ST7 technical data for valid modes.  
The  following  tables  list all ST7 mnemonics recognized by the
ASST7 assembler.  The designation [] refers to  a  required  ad-
dressing mode argument.  


Inherent Instructions 

        nop                     trap
        wfi                     halt
        ret                     iret
        sim                     rim
        scf                     rcf
        rsp


Conditional Branch Instructions 

        jra     label
        jrt     label           jrf     label
        jrih    label           jril    label
        jrh     label           jrnh    label
        jrm     label           jrnm    label
        jrmi    label           jrpl    label
        jreq    label           jrne    label
        jrc     label           jrnc    label
        jrult   label           jruge   label
        jrugt   label           jrule   label

        jra     [saddr]
        jrt     [saddr]         jrf     [saddr]
        jrih    [saddr]         jril    [saddr]
        jrh     [saddr]         jrnh    [saddr]
        jrm     [saddr]         jrnm    [saddr]
        jrmi    [saddr]         jrpl    [saddr]
        jreq    [saddr]         jrne    [saddr]
        jrc     [saddr]         jrnc    [saddr]
        jrult   [saddr]         jruge   [saddr]
        jrugt   [saddr]         jrule   [saddr]


Bit Test and Branch Instructions 

        btjt    saddr,#,label
        btjf    saddr,#,label
        btjt    [saddr],#,label
        btjf    [saddr],#,label


Bit Manipulation Instructions 

        bset    saddr,#
        bres    saddr,#
        bset    [saddr],#
        bres    [saddr],#


Single Operand Instructions 

        neg     []              cpl     []
        srl     []              rrc     []
        sra     []              rlc     []
        sll     []              sla     []
        dec     []              inc     []
        tnz     []              swap    []
        clr     []

        pop     reg             push    reg


Double Operand Instructions 

        add     a,[]            adc     a,[]
        and     a,[]            bcp     a,[]
        or      a,[]            sbc     a,[]
        sub     a,[]            xor     a,[]

        mul     x,a             mul     y,a

        cp      reg,[]

        ld      [],[]


Call to Subroutine and Jump Instructions 

        call    []              jp      []

        callr   label           callr   [saddr]

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Last Updated: October 2010