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1990-02-12
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199 lines
August 04, 1992
* * * * * * * * * * * * * * *
* * * M E S - 1 2 8 * * *
* * * * * * * * * * * * * * *
by Mark Dulski (on GEnie, m.dulski1)
I'm sure most computer hobbiests have at some time viewed an image of a
mandelbrot. Those computer generated swirling bands of color can be rather
remarkable. Often times a pattern is repeated on an ever smaller and smaller
scale, seeming to disappear into infinity. If you were to magnify an area
like that you would find the pattern does not in fact disappear but changes
into something different.
Actually the mandelbrot set is the central blank region that is bordered
by those colored bands. Since the border is so much more interesting that is
what most people identify with and my "Mandelbrot Exploration System" is
designed to explore. Since the Commodore 128 is an 8-bit computer at some
point the accuracy of magnified areas is going to suffer. I do not have a
more powerful 'number crunching' computer to compare the graphics generated by
"MES-128" with so I have no idea when that happens. Nevertheless, the
pictures are interesting!
MES-128 uses the 40 column multicolor (graphic 3) screen to display the
mandelbrot images. The amount of number calculations done when drawing a
mandelbrot is intensive. As you peer deeper (magnify an area) into the image
the drawing time will take longer. Anywhere from just under 2 hours to
several hours or more. I generally start running this program as the end of
the day and turn off everything except the computer, letting it run overnight.
When the program is finished drawing it will return to the main menu and
display the amount of time it took to do the calculating and drawing.
On disk you should have the following files:
MES-128 (the program compiled with BASIC128)
MES128.BASIC (basic source)
MAN.BOX (sprite image needed)
BIT.MANDELBROT (bit image of complete mandelbrot)
CLR.MANDELBROT (color memory for mandelbrot)
DAT.MANDELBROT (program parameters used to draw mandelbrot)
MES128.DOC (what you are reading now ;)
When MES-128 is run a full mandelbrot picture is loaded in memory ready
for you to begin your exploration adventure. Either magnify an area of the
border and/or choose a new color scheme and banding method before redrawing
it. MES-128 can be loaded from and supports any disk drive number 8 to 11.
Enjoy!
<Page 1>
Mandelbrot Explorer
"MES-128"
* * * M A I N M E N U * * *
To make a selection, just press the appropriate key highlighted on the menu.
<C>hange color assignments
Here you will be able to change the backround color and multicolors 1, 2,
and 3 for the next picture to be drawn. You will also be able to change the
color banding scheme. There are 11 banding schemes to choose from. Hard to
explain which one to use when, easier to experiment and see the results.
<E>nter new coordinates
You may enter your own values if you wish, but I find it's much easier to
let the program do it for you by selecting '<M>agnify image'. When the
program is first run the default coordinates are the maximum useful span.
The itineration count is about the only one you will really have use for.
Default is 100 but this can be changed to a lower value for slightly reduced
calculation abd drawing time. Do not go less than 10 for the itineration
count. I may have said you can use a lower value than 100 but there is no
reason you can't use a higher value!
<D>raw image
Self-explanatory. While the picture is calculated and drawn the computer
is put into FAST mode. Press the 'SPACE BAR' at any time to put into SLOW
mode so you can view the picture drawn thus far. Press the 'F' key to return
to FAST mode.
To stop the drawing and return to the main menu press the 'Q' key.
<M>agnify image
The current picture in memory is displayed with a white box in the upper
left corner of the screen. Use the cursor keys to move the box around the
screen and center it over an area of the image you want to peer into deeper.
Press the 'RETURN' key to automatically enter the new coordinates and return
to the main menu. Select <D>raw to start the calculating and drawing of this
new area. You can change color or banding scheme first if you like.
If you change your mind while on the <M>agnify screen, just press the 'Q'
key instead of the 'RETURN' key to go back to the main menu. Nothing will be
changed.
<V>iew image
Allows you to view the image in memory. Press any key to return to the
main menu.
<Page 2>
Mandelbrot Explorer
"MES-128"
<S>ave image
You will be prompted for a filename to save the bitmap image to disk.
Keep the filename to 12 charaters or less. Longer will be truncated to 12
charaters. Three files will be written to disk. "bit.<filename>" is the
bitmap starting from memory location 7168, "clr.<filename>" is color memory
starting from memory location 55296, and "dat.<filename>" is a list of
program parameters used to draw the image that was just saved.
Pressing RETURN without entering a filename will take you back to the main
menu. No image will be saved to disk.
<L>oad image
When prompted for the filename to load you can use the '$' as a filename
to get a disk directory. Use the NO-SCROLL key to pause a long listing. When
entering a filename DO NOT add the "bit.", "clr.", or "dat." prefix. These
will be added automatically before the file sections are loaded.
Pressing RETURN without entering a filename will take you back to the main
menu. No image will be loaded in memory, the one currently in memory will be
preserved.
<K>oala format save
Saves the image in memory as a Koala compatiple file which can be used
with any program that supports Koala pictures. Excellent for slide shows.
Pressing RETURN without entering a filename will once again take you back
to the main menu.
<N>ew disk drive
Repeatedly pressing the 'N' key will cycle through your choice of using
any disk drives 8 to 11.
<Page 3>