Hi Quentin,

To continue from Wagner's response, I'll tell you what I plan to do ( I
have the same problem ).  I already have a fairly large NVRAM as part of my
circuit, so it is not as big a deal for me.

I thought I would reserve a block of memory in the lower address space of
the RAM for text messages. Each text message will be allocated the same
amount of space ( wasteful, but simple .. also, I've got RAM to waste ).
 Each text message will be terminated by a trailing zero. In your program,
you will need the base address plus an error number. Pseudo C code follows
(sorry,  don't speak ASM very well):

#define TEXTMSG1        0
#define TEXTMSG2        1
...
#define TEXTMSGN        N

#define baseAddress 0x00                        // Base memory address in RAM
#define msgSize 30                      // Number of chars in each message

void DisplayMessage( int msg )
{
long addr  = baseAddr + ( msg * msgSize );              // Requires 16 bit math
most
likely
int l;
char c = 1;
int row = 1;
int col = 1;

for ( int l = 0; l < msgSize && c != 0; l++ )
        {
        c = ReadRAM( addr + l );                                // Read a byte f
rom RAM

        // If c == 0, end of string
        if ( c != 0 )
                {
        WriteCharToLCD( row, col, c );                  // Write to LCD
        col++;

        // Handles wrap around
        if ( col > MAX_COL )
                {
                row++;
                col = 1;
                }
        }
}

return;
}


int main()
        {
        DisplayMessage( TEXTMSG1 );
        DisplayMessage( TEXTMSG2 );

        return 0;
        }


HTH,
Eric
-----Original Message-----
From:   Quentin [SMTP:qsc@ICON.CO.ZA]
Sent:   Tuesday, May 04, 1999 10:18 AM
To:     PICLIST@MITVMA.MIT.EDU
Subject:        Handling large tables for LCD display

Hi Picsters
I am currently working on a project which display lots of text messages
and data on a LCD display.
I have about 20 text messages of up too 32 characters each to display.
Some messages will also incorporate variable data (readouts).
I use a 16C74 and 16x2 LCD and write in ASM.
Currently, I got all the messages in tables in page 1 of the memory and
use the standard PCLATH and CALL etc. method of calling them up when
needed.
The variable data I am going to read from register files using indirect
addressing. Still working on this.
As it is now, it works but I find using it and calling the tables very
tedious and the coding gets a bit long at stages. Also, the tables hogs
a lot of memory space.

Anybody got a easier or better way to handle many and long messages for
LCD display?

Thanks
Quentin