OFFSCRPT.8xv (appVar) gets copied to $8001 every time the calculator turns off. This catches both 2ND + ON as well as APD. So instead of going to APD, it can just display your screen saver.

My OFFSCRPT always crashs the calc. The code is copied to $8001 and executed. But every times it reaches bcall(_jForceCMDNoChar) the calculator simply doesn't react anymore


I leaved the
bit   4, (iy + 8 )
out because this way the bit is set always and my code is never executed

By the way:
  Is there a way to store the current value of the PC register somewhere else

a explanation in the tutorial Deep Thought gave me says:
http://eeems.omnimaga.org/files/Resources/Tutorials/ASMin28Days/lesson/day02.html

.org number    Specifies where in memory the program is loaded into (not exactly true), which is always $9D95.

Why is it always $9D95?
I mean if there is stored something other this "other" will be overwritten by the program code.

Deep Thought also mentioned this location in his SMC tutorial:
http://www.omnimaga.org/index.php?action=articles;sa=view;article=91

You also know the absolute location of the start of the program (it's E9D93).

I think SPASM is what I will use.
But is there any readme or something to learn how to use it?

If you also decide to go with this setup, this is what needs to go in your asm.bat file that you make on the first day. This is because spasm has a different command line syntax than tasm:

to be honest I don't really know what this code does and where to put it.
(I have only small experience with batch code)

Yeah I decided to learn ASM so I have read a lot but some questions still remained: 
1. What compiler/assembler should I use
  TI recommens the ZDS but I think it's a bit environment and I only need a compiler with documentation
2. Since the code depends on the compiler I need some documentation (not the TI hardware and routines guides
  but the basic commands like "call" or "ld"
3. Some questions that will appear when I start making my first errors

[3844828282443800]->Pic1P9
[3244828282443800]->Pic1P10
[3244828282443800]->Pic1P11
[3244828282443800]->Pic1P12
[3244828282443800]->Pic1P13
[3244828282443800]->Pic1P14
[3244828282443800]->Pic1P15
[3244828282443800]->Pic1P16
[387CFEFEFE7C3800]->Pic2P
[387CFEFEFE7C3800]->Pic2P10
[387CFEFEFE7C3800]->Pic2P11
[387CFEFEFE7C3800]->Pic2P12
[387CFEFEFE7C3800]->Pic2P13
[387CFEFEFE7C3800]->Pic2P14
[387CFEFEFE7C3800]->Pic2P15
[387CFEFEFE7C3800]->Pic2P16
[3068A4A484483000]->Pic1B
[1058DCDCFC783000]->Pic2B
[609088482848F800]->Pic1N
[60F0F87838787800]->Pic2N
[D6D67C2828287C00]->Pic1R
[D6D67C3838387C00]->Pic2R
[9254382828287C00]->Pic1Q
[9254383838387C00]->Pic2Q
[3828EE82EE283800]->Pic1K
[3838FEFEFE383800]->Pic2K
[FFFFFFFFFFFFFFFF]->Pic3

I think this are the sprites for the pieces.
You could call them by a command like
PtnOn(X,Y,Pic1P9+I*8
where I is the number of the sprite you want to draw.

...and adding AI.

I once made a chess AI on my PC but I doubt it will be possible with Axe on calculators
The calcs are to slow and they haven't enougth memory

thank you a lot 

I have never read that you can do something like that   
So I can easily make new vars.
How many characters can I use to name them and
from where do you know such things?

Oh yes I've found the tutorial from Deep Thought about Self Modifying Code