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Newsletter - September 2000

The ticalc.org Newsletter
September 2000 - Volume 3, Issue 9


Letter from the Editor
Calculator News
Math Tip
Ask ticalc.org
Interview with Thomas Nussbaumer


Hi, and thanks for reading the ticalc.org Newsletter!

We've all been really busy this month, and if you haven't visited recently, you should find our file archives in much better shape. Behind the scenes here at ticalc.org we've started the long-awaited Screenshot Staff. The staff's goal is to get every file in our file archives screenshotted. A hardworking crew of screenshotters has already been assembled and is now feverishly screenshotting the programs in our archives.

The Program of the Month awards will start up again on ticalc.org. Programs will be selected in four categories: TI-82/TI-83/TI-83+, TI-85/TI-86, TI-89/TI-92/TI-92+, and Computer Utilities/Miscellaneous Programs. All programs released this month that are designated as Featured Programs will be eligible.

Our local mathematics whiz Andy Selle continues on his Math Tip series, this time talking about graphing of sequences and such.

This month's newsletter contains another interesting interview, this time of Thomas Nussbaumer, author of TI-Chess. Be sure to read what he has to say. Until next time...

Eric Sun


Compared to previous months, August was a pretty quiet month in the TI community. Perhaps...well...I'm not even going to theorize on the possible causes of that. Onto more important stuff...

Some of the more notable releases this month included Exec Maker v1.0 by Zeljko Juric, which allows useres to convert short assembly routines for use as Exec() statements for BASIC programs. Fred Coughlin released Yoshi's Cookie v1.0 for the 82/83/83+ earlier in the month, and Badja came out with an excellent trivia game called Fantasy World Trivia v1.0.

Even more releases included a few new Julien Muchembled productions, a handful of new programs from the TCPA, and of course TI-Chess v3.0 by Thomas Nussbaumer. Thomas also released TICT eBook Reader v1.50 for the TI-89 and TI-92+, which is touched on in his interview at the bottom of this newsletter.

Oh yeah, and as usual, Patrick Davidson released a few more versions of Phoenix this month for the TI-89/92/92+, and also ported it to the TI-85 and TI-86. The popular side-scroller Sqrxz was also ported to the TI-83 and TI-83+.

Eric Sun


One of the least utilized features of TI calculators is the sequence gr aphing mode. It is available for TI-82, TI-83, TI-89, TI-92, and the TI-92 Plus. It allows you to plot sequences.

If you aren't familiar with sequenc es, according to MathWorld (http://mathwor ld.wolfram.com/), "a sequence is an ordered set of mathematical objects..."

Often, we define a sequence in the form a_n = some expression (a_n is a n a with a n subscripted). For example, a simple sequence is a_n = n. Explicite ly stated, it is made up of the numbers {1,2,3,4,5,6,7,...}. Another interestin g sequence is b_n = 1/n. It is {1,1/2,1/3,1/4,...}.

How does your tica lc.org calculator fit in? Simple! It allows you to see what these sequences lo ok like. Without your TI, you are forced to plot the sequence to see what is go ing on or to intuitively see it. For example... you may be able to see that 1/n tends towards 0 as n->infinity, but that is only a simple example.

In order to graph a_n = 1/n, we need to follow these steps:

1. Go into sequence mode by going to the mode menu and choosing that graphing option.
2. Go into your "Y=" menu.
3. Enter 1/n (for TI-82 and TI-83 users hit the [X,T,theta,n] button)
4. Go to window and set these options:
nMin = 1
nMax = 30
PlotStart = 1
PlotStep = 1
Xmin = 0
Xmax = 30
xscl = 0
ymin = -1
ymax = 1
yscl = 1
5. Hit "Graph" and watch the sequence approach 0 before your eyes :)

Other fun sequences to try are:
a_n = (-1)^n
a_n = (-1)^n / n
a_n = (-1)^n / n + 1
a_n = (-1)^n/n + n/2
See if you can come up with an interesting-looking sequence.

This is a very simple use of the sequence system. It is possible of a lot more interesting applications. A famous sequence you may have heard about is the Fibonacci Sequence. It is defined as follows:

F_1 = 1
F_2 = 1
F_n = F_(n-1) + F_(n-2) (Basically add the previous two to find current)

The sequence goes as: {1,1,2,3,5,8,...}

Let's encode this on our TI, so we can see a graph (or a table).

In Y=:
u1 = u1(n-1) + u1(n-2)
ui1 = {1,1}
In Window:
nmin = 0
nmax = 30
plotStrt = 1
plotStep = 1
ymax = 100000
Graph! That thing grows fast... a little like rabbit-breeding :).

Well speaking of rabbit-breeding, you can see a very good example of advanced sequence graphing in your TI manual. It is titled "Predator Prey Model." If you are interested in what I have been talking about, I highly recommend it. If there is enough interest I'll come up with an even cooler example for next month ;).

If you have any ideas for future Math Tip sections, please email me at aselle@ticalc.org.

Andy Selle


At ticalc.org, we often receive many of the same questions. In this column, we hope to address some of these questions for a broader audience. If you'd like to submit a question, please email it to ask@ticalc.org.

Q: How do I get my program screenshotted?

A: Normally, our newly-established Screenshot Staff takes care of this. However, if you must, you may use the option in our File Upload Form. We normally prefer our screenshot staff doing this because all screenshots must adhere to our strict standards, and the Screenshot Staff is the easiest way for us to regulate the quality of our screenshots. In due time, all the files in our archives will be screenshotted. Just be patient and your file will eventually appear with that red fileinfo button next to it...

If you'd like to contribute by being a member of this elite staff, simply fill out the application form at http://www.ticalc.org/extra/screenshot-application.txt and mail it to ss@ticalc.org. Be warned, however; being on the staff will require considerable amounts of work.

Eric Sun


Email: thomas.nussbaumer@gmx.net

Interview Log
Eric How old are you and what level of education do you have?
Thomas I'm almost 32 (October) and I have studied Telematik (mixture of soft- and hardware topics) at the technical university of Graz/Austria.
Eric What are you currently doing in your career?
Thomas Our company is manufacturing huge automatic and semi-automatic conveying systems (hardware and software). I'm working in the field of software project management in teams up to 10 employees.
Eric What calculators do you own?
Thomas A TI-92 with the built-in plus module running AMS 1.01. There was never the need for an AMS upgrade for me. I thought about it, but after I heard about the new "features" like the size restriction for assembly programs I dropped any update considerations. Besides the TI-92 I still own a worn Sharp PC1401 which helped me a lot during my high school days back in the 80's.
Eric Do you plan to get any new calculators soon?
Thomas Definitely no. Besides the contrast of the LCD I'm really happy with my TI-92+. One of my first computers was an Amiga 1000. From the hardware side (processor, memory, speed) the TI-92+ and the Amiga are almost identical. However the Amiga wouldn't run on 4 batteries and carrying it around isn't that easy compared to the TI-92 ;-).
Eric What do you use your calculator for most?
Thomas I read eBooks during the daily bus ride to my office, and when I'm not reading eBooks I try to work out the solution to one of Zeljko's text adventures.
Eric What was the first program you ever wrote?
Thomas Hmmm. I'm not completely sure, but I think it was a kind of scrolling text on a Sharp 1251 calculator.
Eric How did you learn to program in assembly language?
Thomas I started programming on a C64. The built-in basic was very rudimentary. To get more out of that "sandwich box" you had to program it in assembly language. And I wanted more ;-D.
Eric Do you have any tips for new assembly programmers?
Thomas Since the TIGCC is out I would suggest that new programmers should start coding in C. For newcomers C is much easier to use and the compiler will help you to prevent errors. Best of all is its portability. If you take care of a few generic rules, the same code will run on the PC or on the calculator.
Eric Do you have an idol TI programmer?
Thomas No. No idol. Thats not a term which fits. But I have a lot of respect for people who contribute new ideas or technologies to our "small" community. People like Zeljko Juric, Xavier Vassor, Rusty Wagner or Julien Muchembled; I cannot mention them all. I'm also glad to see more and more of them turning to the Open Source idea. It's childish to fear that someone will steal your ideas. If someone steals them, why bother? He will be the second who comes up with the idea. He will not be mentioned. And even if he is mentioned, just take up a new idea! There are so much ideas around that nobody takes notice of. Really creative people don't have to fear plagiarists. You can't sit on your "secrets" like a chicken on its eggs. That's contra-productive. If you sit on them, they will "die". If you open them to others, they will get reproduced, extended, and improved.
Eric What projects are you working on now?
Thomas Definitely too many ;-). My main project is the TI-GCC Tools Suite. The recently released eBook reader and its eBooks are a kind of side effect of this tools. The suite itself is aimed towards programmers. I cannot say if the tools are useful; some are, some may not be, but it should be seen as a starting point. During the development of TI-Chess and some other programs there was always the need for some of these tools, but each time, it took me a really long time to find an already existing program that did the job. All of them were spread over different servers and almost none of them had the source code attached. The TI-GCC Tools Suite should be seen as a pool of tools that you can use just as they are, or you can modify the source and build your own tools out of them. That's the main idea behind it. You need a kind of converter? Just take the code of a similar tool and adapt it to your needs. But I'm a little bit worried about the project state. It grows too fast and there is no time to do the "administrative" side like documentation and tutorials.
Eric How did you get the idea to write TI-Chess?
Thomas I always wanted to have a tiny unit which is competitive enough in playing chess. I know that there are chess modules for the Game Boy, but playing with a Game Boy as a 30+ looks like a little bit foolish in public. Additionally I want more control over the chess program itself which cannot be offered by any console game. Doing such a project with pure assembly would be a nightmare when it comes to time and effort. I looked around in each file archive that I had found and even checked the news archive, but I found only chess boards with no AI and a few announcements. Even the announcements were really old. And as the TI-GCC development environment arrived everything was clear to me.
Eric Have you been pleased with its reception in the community?
Thomas Oh, I'm very pleased with it. Sometimes it's almost too much for me. Since I started the project 6 months ago the TI-89 version alone has received over 12,000 downloads at the ticalc.org file archives. I had never expected this to be possible.
Eric What do you think of TI's protections and limitations on their FLASH software for the TI-89/92+?
Thomas Hmmm. I'm in conflict now, because I don't want to get kicked of the alpha tests of their SDK. However, indeed their "features" are idiotic. Software piracy on the TIs? Laughable. Software piracy could be also handled with reasonable prize politics. All that I want is to use the complete hardware I have bought. Heh, there is memory within and someone tells me that I'm not allowed to use it! I cannot see the reason why I should pay for something that I already own. I want a FLASH version of TI-Chess; I want my preferred literature in the FLASH memory, too. I want Zeljko's Adventure Collection in the FLASH. Without any restrictions and without additional payment. It's really sad to see the direction in which direction TI proceeds. I wonder why they won't see that there cannot be any real safe protection. There will be always a way around whatever they build in. Wasted time. On both sides. With the only difference that the hacker may enjoy his hack sometimes.


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