INT 62 u - FGDRIVER v3.03 - "FG_CIRCLE" - DRAW UNFILLED CIRCLE
        AX = 000Dh
        BX = radius in horizontal screen space units (> 0)
Notes:  For FGDRIVER v1.10, this function was "FG_YALPHA" (see AX=00B2h);
          "FG_CIRCLE" was AX=0030h
        The circle is drawn in screen space, centered at the current graphics
          cursor position
        This call is ignored in text modes
SeeAlso: AX=0006h,AX=0008h,AX=000Eh,AX=0024h,AX=0079h

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