8-bit Computer Clock - Page 2

Bread Board Testing

I built the circuit on a bread board for testing.

Thew following video shows the LED flashing while testing the 500Hz Clock and the Manual Clock.

The following video shows the 500Hz clock signal on an oscilloscope as it is adjusted from about 1.5 seconds up to 2ms as was expected.

To test the 5MHz clock I built a digital counter on another breadboard using some 4027 J-K flip flops. Each Flip Flop effectively halves the frequency. With 4 flip flops connected one after the other the frequency is reduced to a 16th the original, from 5MHz to 312.5kHz, which is just about what it does measure. The video below shows the 5MHz pulse and then each of the 4 flip flop outputs. The final signal looks different because it was measured across a LED on the 4th flip flop.

PCB Layout

I designed the PCB using KICad. To keep with the fashion of naming computers after fruit I called this one an Illawarra Plum, which is a native fruit where I grew up.

I will get the PCB ordered in the future, but for now I built the circuit on Vero Board and used the laser cutter to make a box from MDF.