Ti86 modifications

[iteration69]

I just found this forum so yes i'm new. If this is breaking any new posting rules i may have read over let me know.

Back to the subject. I've managed to find a way to add a light to Ti calcs pretty easily and not so expensive. Cost me about $20 for the first one. It doesnt consume much power (about 1/3 of what the calc normally uses when executing an assembly language program without halts) Its real easy to install compared to some of the other "butcher your screen" methods. and it doesnt take much time. Anyway its online
http://video.google.com/videosearch?q=ti+8...ght&sitesearch=

With enough interest i'll right a complete "how to" on this.

The second subject here is Link I/O. I wrote some code to link to the calculator and a microcontroller via the link. It is pretty strait forward simply use TiBasic to interface with the real world. Pretty much a CBL other than the method of interface in terms of programming - and the fact that i can change anything i want. Cant really do that with a cbl. I started a project on source forge on this one but have been lazy and have yet to upload any project details. Interest is the big factor here. I'm not going to waste my time on something others will not appreciate. However if this forum is still alive there may be an interest, in that case i have about 10 years of tinkering that i will share.

Enough of the ramble. The IO interfaces uses basic functions such as Get() and Send(). the MCU acts like another Ti86,Ti85 and negotiates the interface to TIOS. What this means is that the mcu handles all low level data transfer functions such has bit, byte, packet, BCD formation. ATM i can get real world ADC values, and logic. I can also remotely control the calculator from the MCU which enables quite a few tricks.

Well, hopefully there is still some interest in these calculators like there was back in the late 90's.

Here is a site with some legacy work, back in the day - if you will.
http://www.shol.com/shadow_tech/archive/ti8x/index.htm

Playing the url you are likely to find other sections of things i have worked on and documented (documentation is NOT my strong point, unless their is sufficient motivation behind it)


Steve

[JoostinOnline]

That is amazing!
Oh, and welcome to UTI

[TheStorm]

Hey do you have any pics of what the inside of you calc looks like with the light added I have an 86 that I would love to do this too.

[iteration69]

I'll try to find some time to pull it apart and take some pictures. This should work on just about any of the graphing calculators. A friend wanted it on his ti89 we managed to get it installed. The biggest problem is finding a good power signal source. I have that all covered for the 86 and 89. IIRC it takes two resistors and one transistor.

The light diffuser was pulled from a broken GBA. I managed to find a seller on ebay that had a few broken screens so i bought them for the front light diffuser.

I was amazed to find just how well it fits inside the calculator.




Steve

[TheStorm]

Hmm do you really need the light defuser or can you do it without? And does this use LEDs?

[iteration69]

It is a white led. A very efficient one at that. It easily competes with EL in terms of power and light output. And about the light diffuser, i really dont think it will work well without it. You see the light diffuser is split into two sections. The first is a horizontal light pipe that supplies the front diffuser. The front diffuser takes that light and deflects it onto the screen. It does this with very small slices that act as 45 degree mirrors. The slices are small somewhere in the micrometer range. You cant see the lines directly but you can see the light spectra if held at specific angles to light. - something like what a cd does in the light but not to such an extent. just to give an idea of things.

As i said the led power is small, very small. It can easily to be adjusted to conserve more power by changing the drive resistance value. I have mine set at roughly 1/3 max power ussage which gives a decent light output. Good enough to be a flash light in a dark room.

I have not noticed a substantial operating time difference since i have added the light. I'm guessing that i have been using the light for about 8 months now. Consider i use NiMH batteries so the actual voltage is a great deal lower than can be expected in comparison with alkaline batteries. Fresh charged NiMH = 5v, alkaline = 6v. This translates into number ~5 on contrast with good charged NiMH batteries. I use my calculator rather extensively (~1hr day) 3-4 days a week and have charged the batteries 4 or 5 times since the light has been added. One thing i need to note here is that i am not running games that use 100% of the cpu. I am using the calculator as a calculator so most of the time it is in low power mode. Considering the additional use i get out of my calculator now (poorly lit rooms) it is well worth the small price i pay in terms of battery life. Also, the light automatically turns on and off with the calculator. This can be good and bad depending how you consider things. Obviously if you don't need the light and it is on -some power is being wasted. From my experience though, it even helps in well lit areas. Now all i need to do is find a way to light up the keypad.

When i go home i'll try to put something together for reference.

Steve

[TheStorm]

Cool ok How much did the light difuser cost you so I know what I am dealing with and then I'll look at getting the parts.

[iteration69]

IIRC i paid ~15 for the first broken GBA SP on ebay.

I put some of the pictures together with some write up. It is not quite done yet but it should give you a good idea.

http://www.shol.com/shadow_tech/ti86/screenlight.html



Steve