I have a program working which reads telegrams from a bus and displays some 
info on an LCD.
The program is split on 3 files:
- Main
- Bus (receiving telegrams)
- LCD control

there are variables defined in each part. Some are globals in each part.

The LCD part has only 4 variables defined (UDATA), one of which is global 
(temp_wr) and is accessed from the Main.
This global variable contains the data for LCD display (one Byte)

The whole program worked until I added some more variables (in the Bus 
part),
when the LCD displayed a row of weird characters (C0h)
Checking the map file, I found that the variables were all in bank 0, 
starting at 080h,
but when I added more variables, the 4 variables from the LCD part were 
shifted into bank 5,
starting at 500h.
Further tests showed that ONLY if the global variable temp_wr is defined in 
the LCD part global
(and in Main as Extern), AND it is in bank 5, it shows that problem.
If however I put the same variable into Main as global and use it in LCD 
(Extern), it works fine, no matter in which bank it is.

Of course I can use it this way, but I like to understand what's going wrong 
here.
Is it bad programming style to define a global variable in other than the 
Main part?
and yes, I did RTFM, but did not find a relevant hint.

Thank you all for any help
Lembit 

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