25 Years of Programming
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Programs in DeSmet C for the Heathkit H-100 computer

In addition to the programs on this page, the site has some Borland C programs that were originally in DeSmet and might be converted back to it without too much difficulty. A few of them may have such a comment in their source code, and could be found by searching this site for "DeSmet".

Each link below goes to the project page, which has a more complete description and code listing.

Programs that generate graphics files

Mandelbrot set	Calculates and displays regions of the Mandelbrot set.
Random IFS Fractal Generator	Continuously draws fractal shapes from randomly-generated Iterated Function System sets. Has several calculation and display options, including save to disk.
IFS fractals from disk file data	Reads file data for an Iterated Function Set in either rectangular .IFS or polar .PFS format, calculates and displays the fractal design that it defines.
Logistic Map Bifurcation Diagram fractal display	Shows Robert May's bifurcation diagram, as described in Chaos: Making A New Science, by James Gleick.
Graphics screen bitmap editor program	A graphics screen bitmap editor for the H-100. Uses .PIC format files.
Diffusion limited aggregation simulation (DLA)	Simulates diffusion limited aggregation. Particles randomly wander around the screen. When they collide, they stick together.
Normal distribution display	Builds a normal distribution at the bottom of the screen, but has the "sticky" routines from DLA.C, so it makes strange treelike formations at the screen bottom, instead, in a vaguely normal distribution.

Programs that transform or manipulate graphics files

Each of these simple programs is mostly boring and useless until you need to do the thing that it does.

Dealing with .ZED files

The .zed graphic format was one I invented for use on the H-100. It is like a device-dependent bitmap. It stores the raw data from the red, green, and blue color plane RAM banks to a disk file. The files save and load very fast. A predecessor, referred to in a few places, was the monochrome .ZIC format, which saved only the green plane data.

Dealing with .PIC files

I also invented this .PIC format for the H-100. It is like a device-independent bitmap. It stores the color values of consecutive pixels as consecutive chars in a disk file. Each char of a .PIC file can hold values from 0-255 even though the H-100 only has 8 colors.

Display a single .PIC file to the H100 screen
Display a "side view" of a .PIC file. This was an attempt to view Mandelbrot designs from the side. It has some options how to display the result.
Adjust (crop) the dimensions of a .PIC file
Invert the color indices in a .PIC file. 0 -> 255 becomes 255 -> 0. In a Mandelbrot design where color indices map to "elevations", mountains become valleys and vice versa.
Smoothe the color values in a .PIC file. Reduces the jaggedness of a .PIC file by converting its values to n-item moving averages, at least horizontally. This is similar to "blur" in more modern graphics programs.
Turn a .PIC file upside down (flip vertically). Rewrites lines from a .PIC file in reverse order to a new file. Line 225 becomes line 1 in the new file, etc., so the image is turned upside down.

Miscellaneous Other Programs

Translate Iterated Function Set from rectangular to polar notation	Translates (unreliably) an IFS set from rectangular to polar notation. Has links to subsequent programs that do it better.
Copy one video RAM color plane to another	Merely copies the contents of one color plane into another, demonstrating two methods for setting video memory, using _poke() and _lmove(). Very fast.
Statistics calculations	Statistics program reads data from a file, outputs statistics in table format to another file. For one or two variables, calculates n, sum, mean, standard deviation, correlation, slope (m), y-intercept (b), and predicted y for each x. Originally written in DeSmet C, this program listing is actually in Borland C, but converting it back to DeSmet should be easy.
Loan amortization schedule	Computes a loan amortization schedule, showing the payments required to pay off a loan, and for each payment, the amount allocated to principal and the amount allocated to interest.