I'm using a Data I/O chip writer to program the chip. For the actual coding I'm using READS400. I'm using the following code to write the values to the ports so I can test whether or not the chip is being programmed.

while(1)
{
#asm
mov P0, 0x128
mov P1, 0x254
#endasm
}

READS400 generates a hex file which I use to program the chip. But when I test it, there are different values on the ports. Any suggestions?
I'm a student doing a senior project and slowly learning this device.