Some explanations to
MANDELBROT VER: 5.7, 11 Mar 1992
By  H†kan Malmqvist
    AM elektronik
    Grevgatan 49
    S-114 58 Stockholm
    SWEDEN
    Tel + 46 (0)8 661 07 34
    Fax + 46 (0)8 663 20 34 

General remarks

Only for 386 + 387 PC:s with a Microsoft compatible mouse.
    Allways use <ENTER> for confirming input and choises. Since there is
litterally no escape (the Esc button is not implemented), once you have
chosen an option, just go on with Enter (Return), also for backing to the 
last menu.
    To get started just accept the default values and press return
till the first picture appears.
    Use mouse only to place and size the zoom box. Left button = move box.
Right button = resize box.


Menu options

Plot window Y/(N)       <ENTER> for full 480x480 pixel picture.
                        <Y>. Place and size the picture with the mouse.
                        A small picture means a fast picture. You can
                        zoom out from a small picture by making the zoom
                        box bigger than the picture frame.

Iterations <50>         <ENTER> gives default value (50).
?                       Input new value, <ENTER>. Max value is 32000.

Col. factor <1.00>      <ENTER> gives default value (1.00).
?                       Input new value, <ENTER>.
                        1.00 means constantly 4 iter. between new colors.
                        >1 means an gradually increasing count of iter.
                        before changing color. The iteration width of a
                        color band is multiplied by the color factor to
                        get the next width. Factors 1.0 to 1.2 gives
                        pleasing results.

<ENTER> = go, stop      Use any other alphanumeric key to pause and
                        resume.

Load                    <L>. Input the name (without extension) or press
                        Enter for accepting the default name. The picture
                        is placed in the upper, left corner regardless of
                        size and placement when it was saved.

Save                    <S>. Input the name (without extension) or press
                        Enter for accepting the default name. If the file
                        already exists confirm overwriting it with <Y>.
                        If you want to save only part of the screen use 
                        the mouse to frame the picure in the zoom box
                        BEFORE pressing S.

New                     <N>. Select left (min) and right (max) real
                        coordinats and center imaginary coordinat for a
                        new picture.

Color                   <C>. Then use numeric keypad to move up <8> or
                        down <2> between the 16 simultaneous colors.
                        Left <4> or right <6> will select another color
                        register for the selected color number.

    <C>, <S>, <L>       Select (C)olor hue, (S)aturation and (L)uminans
                        for change with <+> or <->. Color values are from
                        0 (blue violet) over purple back to blue violet
                        at 3 for a full turn around the color circle.  
                        Saturation and luminance go from 0 to 1.

    <A>                 Autocycle the colors randomly. Change direction
                        with <+> and <-> and pause/step with <SPACE>.
                        Continue autocycling with <A>.

    <D>                 Returns to the default palette.                   
    
    <E>                 Erase the screen in the selected color.
                        (Now just select another color and start painting
                        with the left mouse button!)

Quit                    <Q>. Imediately quits to dos.


Programming remarks
 
    The programe is written in Turbo Basic in a way that reflects its 
organic growth. It is rather messy!
    An optimised assembler floating point routine (MANDEL.ASM) is used 
for the inner iteration loop. It makes 4 iterations before comparing for 
jumping out, to reduce overhead. It probably works only for 387 
coprocessors. All iterations is performed on the coprocessor stack and 
conserve the internal 80 bit format to maintain precision and speed.
    Assembler routines are also included for writing and reading a pixel
on the screen, and for writing a box on the screen (the 5x5 box of the 
first pass).

END.