This just draws the four dimension lines from 4D Rotocube, then some
octagons.  FYI, "SETDP" is a directive for the assembler I use so it not
only won't bitch about "<address" DP references, but it will automatically
handle them as well.  Plus it makes the code a bit more readable by
making DP register changes more visible.

                INCLUDE VECTREX.INC
                LIST    ON
                SETDP   $D0             Carts start up with DP = $D0

                FCC     /g GCE 2001/
                FCB     $80

                FDB     $FF8F

                FCB     -8,72           h,w
                FCB     32,-48          y,x
                FCC     /VEC TEST/
                FCB     $80

                FCB     $00

                INC     Vec_0Ref_Enable This is kind of important

Start           LDX     #Vector_Table   Get address of vector list

Loop            JSR     DP_to_D0        Vector routines want DP = $D0
                SETDP   $D0

                LDA     #$CE            Reset0Ref left the integrators in zero
                STA     VIA_cntl          mode, so set /BLANK low, /ZERO high

                JSR     Mov_Draw_VLcs   Draw vector list (calls Check0Ref)

                LDD     ,X              End of list if count=0 and scale=0
                BNE     Loop            Go back for more if not end of list

*               JSR     DP_to_C8        Music routines want DP = $C8
*               SETDP   $C8

*               LDU     #music          (if we had something to play)
*               JSR     Init_Music_chk  (if we had something to play)
                JSR     Wait_Recal      Wait for time to draw next frame
                SETDP   $D0             Wait_Recal sets DP to $D0
*               JSR     Do_Sound        (if we had something to play)

                BRA     Start           Go back to draw next frame


Vector_Table

*               These first four were ripped off from the 4D Rotocube demo

                FCB     2,80            count,scale
                FCB     127,0           Y,X
                FCB     -127,0          y,x
                FCB     -127,0          y,x

                FCB     2,80            count,scale
                FCB     0,127           Y,X
                FCB     0,-127          y,x
                FCB     0,-127          y,x

                FCB     2,80            count,scale
                FCB     127,127         Y,X
                FCB     -127,-127       y,x
                FCB     -127,-127       y,x

                FCB     2,80            count,scale
                FCB     127,-127        Y,X
                FCB     -127,127        y,x
                FCB     -127,127        y,x

*               And now some octagons.  They are drawn clockwise, with
*               the origin point at the left end of the topmost line.
*
*               Note that they come out brighter than the longer lines,
*               probably because the lines are being drawn in a constant
*               time period (which would be the scale factor).  Hopefully
*               this effect is only visible with the longest of lines.

                FCB     8,80            count,scale
                FCB     96,-64          Y,X
                FCB     0,5             y,x
                FCB     -5,5            y,x
                FCB     -5,0            y,x
                FCB     -5,-5           y,x
                FCB     0,-5            y,x
                FCB     5,-5            y,x
                FCB     5,0             y,x
                FCB     5,5             y,x

                FCB     8,80            count,scale
                FCB     96,64           Y,X
                FCB     0,5             y,x
                FCB     -5,5            y,x
                FCB     -5,0            y,x
                FCB     -5,-5           y,x
                FCB     0,-5            y,x
                FCB     5,-5            y,x
                FCB     5,0             y,x
                FCB     5,5             y,x

                FCB     8,80            count,scale
                FCB     -96,64          Y,X
                FCB     0,5             y,x
                FCB     -5,5            y,x
                FCB     -5,0            y,x
                FCB     -5,-5           y,x
                FCB     0,-5            y,x
                FCB     5,-5            y,x
                FCB     5,0             y,x
                FCB     5,5             y,x

                FCB     8,80            count,scale
                FCB     -96,-64         Y,X
                FCB     0,5             y,x
                FCB     -5,5            y,x
                FCB     -5,0            y,x
                FCB     -5,-5           y,x
                FCB     0,-5            y,x
                FCB     5,-5            y,x
                FCB     5,0             y,x
                FCB     5,5             y,x

                FDB     0               end of list

                END