read write particular location on External RAM

Hi all,

can any body help me how to write and read the particular location on external RAM (accessing the memory address ).

I am trying the Code:

#define POSITION 0X12000

void main()
{
unsigned char xdata chr;
unsigned char str;

chr='A'
ram_writep0(POSITION,chr);

str=ram_readp0(POSITION);

}

void ram_writep0(unsigned char posi,unsigned char writechar)
{
SRAMA16=0;
SRAMA17=0;
SRAMA18=0;

DATAPORT=posi;
SEL573L=1;
// _nop_();
SEL573L=0;

DATAPORT=0;
SEL573H=1;
//_nop_();
SEL573H=0;

DATAPORT=writechar;
SELK6=0;
WR=0;
//_nop_();
WR=1;
SELK6=1;
}
unsigned char ram_readp0(unsigned char posi)
{
unsigned char tempdata;
SRAMA16=0;
SRAMA17=0;
SRAMA18=0;

DATAPORT=posi;
SEL573L=1;
//_nop_();
SEL573L=0;

DATAPORT=0;
SEL573H=1;
//_nop_();
SEL573H=0;

DATAPORT=0XFF;

SELK6=0;
RD=0;
// _nop_();
tempdata=DATAPORT;
RD=1;
SELK6=1;
return tempdata;

}

I want to write 'A' on specific location and read it from there....
does i m doing write

Any new method is also welcomed.

Thanks