After the portable ZX Spectrum, Ben decides to take on another retro 8-bit computer project and builds an Apple 1 from scratch. He wires the CPU, ROM, and RAM to a PCB and adds some logic gates for memory addressing. With this basic 6502 computer complete, he uses an oscilloscope to take a look at what the CPU is doing. The digital data shows that the 6502 is functional and Ben can move on to the next step.
Source: Call A.P.P.L.E