PTO Tracker isn’t the first app I’ve sold. Back in high school, I wrote a program for the TI-82 calculator. It was in Honor’s Advanced Algebra and we were doing 3 system equations. What are those? The problem looks something like this:

3x + 5y – 2z = 20

4x -2y + z = 16

-x + y + 8z = 24

And the answer would be the value of x, y, and z that make all three equation correct. Basically, each equation is a plane in 3D space. If you intersect two planes, you have a line. If you intersect that line with another plane, you have a single point. I have no idea what a word problem would be for this.

Of course, it’s always good to check your work. I suppose you could check your work manually, but I decided to write an app (back then they were called “programs”, or on the TI-82, “PRGM”) to do the solving for you. Since you had to show your work anyways, it’s not like you’d be able to use this to cheat. So I went home one day and sat down and figured out how to use all the variables to get the correct answer. Now, this was a bit tricky because the TI-82 only had 26 variables, and 12 of them were already taken up by just the input of the program. You also have to realize I had no further explanation on how to program besides reading the calculator manual. I didn’t think about storing the values in matrices or things like that. I didn’t try to figure out when variables were no longer needed and overwrite them. I probably could’ve if I couldn’t manage with 26 variables. But I managed. After I had everything planned out, I programmed it into my calculator.

Some classmates saw the program and I sold it to them. I think most people gave me a dollar. One person liked it so much, he gave me $5. Now, selling TI-82 programs is kind of a hit and miss. There is no App Store. It involves you linking up your calculator with the other person and doing a “Send”. Once you give the program, the other person is able to modify it if they want to remove your name from the credit or they could copy it to all of their friends. I’m not sure how many people got the program for free. But I did make some money off of it, which is pretty nice when you don’t have a job.

I even remember sitting in class one time and a classmate was arguing with the teacher about something that got marked wrong. Her response was, “Well, Bryan’s program said this is the correct” and she got cut off by the teacher, “I don’t care what the program says, you did it wrong.” My guess is the data was entered incorrectly, since when I was doing the answer, I got it right.

So that was my earliest experience selling software. What was yours?