The circuitry of the system unit usually is part of or is connected to a circuit board called the?

The circuitry of the system unit usually is part of or is connected to a circuit board called the?

سسٹم یونٹ کی سرکٹری عام طور پر سرکٹ بورڈ کا حصہ ہوتی ہے یا اس سے جڑی ہوتی ہے جسے کیا کہا جاتا ہے؟
Explanation

The circuitry of a computer's system unit is usually part of or connected to the motherboard, which is the main circuit board.

The motherboard is also known as the system board or logic board.