Having major problems. It looks like the chip isn't accepting code. How?? Why??? First i thought it might be due to the ALE timing problems. So i tried various values for the delay ( I used a do while loop). That didn't solve the problem. So i checked the algorithm, that too was correct, i think. The datasheet has an algorithm and timing diagram. There is a sight confusion there. Should EA/Vpp be raised to 12V then apply the address + data routine as the timing fig. states or, the other way round as the alogrithm states??
What will happen if the prog width is more than 110us?? will the chip suffer permanent damage?

regards,

Sushil

p.s. I don't think it is a hardware problem as i get the address, data, 11.9v/4.97v, etc, at the right pins.