1. Check whether the oscillator is running at all!

2. Try it with a 10MHz quartz and slightly bigger burden caps.

3. Remove the cap and pull-down resistor of reset circuit. Add a 4k7 pull-up to RST pin and let the ISP-cable control the reset line.

4. Do you use the updated ISP software, which knows the AT89S8253?

5. ISP software wants you to input clock frequency of micro. Input the lowest frequency possible (I think 3MHz, if I remember correctly).

6. Before connecting your micro to the cable, first initialize the ISP software. It will quit this with an error message. Then connect the target and initialize again. (At first attempt reset line isn't high and can cause malfunction. After the first initialization, even if it failed, the reset line is high and target will see a valid reset signal.)

7. 74VHC244 isn't TTL compatible, but most PCs and laptops emit TTL-signals! This can cause malfunction, especially in a noisy environment. You can try this circuit as remedy:

(Explained here:)
http://www.8052.com/forum/read.phtml?id=103574



Good luck,

Kai