To capture the ones and zeros coming out of a 6502, the only connections are the eight pins on the data bus, RnW, Sync, Rdy, and Phy2. That’s only twelve pins, and no connections to the address ...

The 40-pin 6502 alone takes up nearly two-thirds of the connections available; add in equally large but necessary chips like the 6522 interface adapter, ROM and RAM chips, and some support ICs ...