Dear Eric,

You just have to do a few works!!

First of all you have to put the IC of 8051 on your target board and then you turn power on your tartget system.

Also, you need an osciloscope and connect the one channel of oscil. with the pin 18 and after with the pin 19.

You should see an sin singal (maybe little deformed) and then you are sure that your external oscilator is working properly.

I hope I understand you correctly.

Feel free and contact with me for any question.

That's all and good luck

Vagelis katsos