I think that I start to understand how things work...

Please, see if I'm thinking right... scenario: reading a voltage trough an ADC, let's say... 3.16 volts... I will store a string like

"Voltage is:", 00h ; 00h is the end of string, as you said...

then I start to convert the binary output from the ADC, converting one character at time... the first is '3', the second a '1' and the last '6'... so I could "print" them in sequence with the first string, that is already in the LCD (positioning the in the proper row, column, etc)... that is it??

Well, I can do that :-) just a little time more...

but I have an doubt now... if I can't read data from external memory and put it in the code memory... what is the importance from external memory? I can't move a block of memory from code memory to external memory... I can't move a block from external memory to code memory... it seems good only if that external memory is being read by another device than the 8051... and that device could manipulate the data...

Another question, there is some directive in compilers that say " that data is to be written in the external memory" ??? I'm using Proview32, from Franklin Software to develop my programs... but never seem something like this...

If I could do this I could have all the words that I want to display in the XDATA and could read the whole word at once...

something like

org 2000h
...
XDATA_directive ;
DB 'Hello World! good MORning',0 ; that phrase is going to be written in the ;XDATA area
CDATA_directive;
DB 'System is up!',0 ; that phrase is going to be written in the code memory ;area
...

there is such a thing???