Thank you for the information.
The pointer now is on xdata.
My internal RAM has become wider now.

But I got another problem here.
I have the external interrupt routine handler code like below:

extkeyboard() interrupt 2 using 2
{
switch (KB_cnt)
{
case 0:
KB_cnt++;
break;
case 1:
case 2:
case 3:
case 4:
case 5:
case 6:
case 7:
case 8:
KB_byte = KB_byte>>1;
if(KB_BIT)
{
KB_byte += 0x80; KB_parity++;
}
KB_cnt++;
break;
case 9:
KB_cnt++;
break;
case 10:
KBbuff[KBbuff_head++ &(KBbuff_LEN - 1)] = KB_byte;
KB_cnt = 0;
KB_byte = 0;
KB_parity = 0;
}
}

This routine is working properly on 32kb SRAM (HY62256-LP70). But when I use the bigger memory 128kb SRAM (UT621024PC-70L) with memory paging, the data store on circular buffer KBbuff[] sometimes does not match.
Please suggest.
-what the thing that I must pay attention when using large memory type? (there is no problem in the hardware connection, another routine is working)
-is it about read/write speed problem?
-how to simplified my routine above, to get the better performance? (the circular buffer using 256 bytes xdata)

Thank you,
Sakri Agiyanto