ADC0808 to read 4 channels. Each channel is a simple 0-5V from a 1K potentiometer.

89c52 in control.

Two channels working fine.

Next two channels activated today.

All four channels go for a spin - in fact the confusion was so much that I started believing in luck.

OK after some swapping of channels, actually found out that channels 3 & 4 are the culprits - not only they read incorrectly - they also end up crashing the poor 89c52.

Maybe someone had this problem. Maybe not. But just trying to warn that just because two channels are working fine, it doesnt mean the whole chip is fine. Like a human it also can have a stroke and loose some functions..

Would like some more views on such cranky behaviour.

Raghu