Here are a few design principles:

• The main objective is the learning experience. Therefore optimisation is not the goal neither in component count nor in performance. Anyway when building a TTL base computer, performance cannot be the goal.
• All components are 74LS or 74HCT series bought new
• All is positive logic.
• Leds are put eveywhere the undestanding of the inner workings is required (bus, status, actions signals, register values, etc). Leds are the better and easy way to display signals. Each led is protected by a 330ohm resistor (5v power supply, 1,4V drop at the led. Therefore 3,6V at the led level. With a 330ohm resistor it allows for a 10mA current)
• When needed pullup or pulldown resistors are 1kohm
• Each IC as a 0,1uF capacitor close to it for decoupling and power reserve
• Each power line has a 100uF capacitor as a power reserve