[SOLVED] AD1674 with AT89C51 convert using 74HC74 and 74HC00

Code C - [expand]
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#include <reg51.h>
#include <INTRINS.H> 
#include <STDIO.H>
 
 
sbit STATUS = P1^0;
 
unsigned char xdata CTRL _at_ 0x2FFF; //Why define CTRL at the external Address?
unsigned char xdata ADSEL _at_ 0x4FFF; //Why define ADSEL at the external Address?
unsigned char hByte;
unsigned char lByte;
 
void adc_Convert (void)
{ 
 
CTRL = 0x00; //Why assign 0x00 to the address? And What delegated for the CTRL?
ADSEL = 0x00; //Why assign 0x00 to the address?
 
while(STATUS==1);
 
CTRL = 0x02; //Why assign 0x02 to the address?
hByte = ADSEL; 
 
CTRL = 0x03; //Why assign 0x03 to the address?
lByte = ADSEL; 
}
 
 
void main(void)
{ unsigned int delay, MSB , LSB, adc_Res;
 
SCON = 0xDA; 
TMOD |= 0x20; 
TH1 = 0xFD; 
TR1 = 1; 
TI = 1; 
 
while(1)
{ 
adc_Convert();
MSB=(unsigned int)(hByte << 4);
LSB=(unsigned int)(lByte >> 4);
 
adc_Res = MSB + LSB;
 
printf("ADC READINGS: %03Xh\n", adc_Res);
 
for (delay=0; delay<10000; delay++) 
;
}
}