Complex sentence: Transistors were expensive at the time and each logic gate requires only one to amplify the output winding pulse; however a single transistor drives the inputs of a small number of (typically 3) other cores.
Split into simpler sentences: Transistors were expensive at the time and each logic gate required only one to amplify the output winding pulse. However a single transistor could only drive the inputs of a small number (typically 3) other cores.