The VDD pin is the one that supplies power to to chip.

So, Yes: the VDD pin must have a suitable voltage supplied to it by your external power supply cicuitry.


The 89C52 Datasheet will tell you what supply voltage it requires for correct operation.

1V is almost certainly not a valid supply voltage for an 89C52!!

If you remove the chip, does the voltage stay at 1V?
If it does, then your power supply is broken.

If the voltage is correct with the chip removed, but drops to 1V with it in place, that could indicate a number of things:

Your power supply is broken or inadequate - it can't supply sufficient current for the 89C52;

The 89C52 is broken - it is drawing too much current, and that's causing the supply voltage to drop;

etc...