ASST6 Assembler


The following is a list of the ST6 registers used by ASST6:  

        a       -       8-bit accumulator
        x,y     -       8-bit index registers
        v,w     -       8-bit scratch registers


     The following list specifies the format for each addressing
mode supported by ASST6:  

        r               register (a,x,y,w,v) addressing

        #data           immediate data byte

        dir or *dir     8-bit zero page addressing
                        0 <= dir <= 255 

        ext             12-bit extended addressing

        (x) or (y)      register indirect addressing

        label           pc-relative branch addressing

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

     Note that not all addressing modes are valid with every in-
struction, refer to the ST6 technical data for valid modes.  
The  following  tables  list all ST6 mnemonics recognized by the
ASST6 assembler.  

Inherent Instructions 

        nop                     ret
        reti                    stop

Conditional Branch Instructions 

        jrc     label           jrnc    label
        jrz     label           jrnz    label
        jrr     #,*dir,label
        jrs     #,*dir,label

Bit Manipulation Instructions 

        set     #,*dir          res     #,*dir

Single Operand Instructions 

        clr     a               clr     *dir
        com     a

        dec     r               dec     *dir
        dec     (x)             dec     (y)
        inc     r               inc     *dir
        inc     (x)             inc     (y)

        rlc     a               sla     a

Double Operand Instructions 

        add     a,(x)           add     a,(y)
        add     a,*dir          addi    a,#

        and     a,(x)           and     a,(y)
        and     a,*dir          andi    a,#

        cp      a,(x)           cp      a,(y)
        cp      a,*dir          cpi     a,#

        sub     a,(x)           sub     a,(y)
        sub     a,*dir          subi    a,#

Call to Subroutine and Jump Instructions 

        call    ext             jmp     ext

Load and Store Instructions 

        ld      a,x             ld      a,y
        ld      a,v             ld      a,w

        ld      x,a             ld      y,a
        ld      v,a             ld      w,a

        ld      a,*dir          ld      *dir,a

        ld      a,(x)           ld      a,(y)
        ld      (x),a           ld      (y),a

        ldi     a,#             ld      *dir,#

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Last Updated: March 2021