The edge connector or external interface at the rear of the ZX81 is an extension of the main printed circuit board. This provides a set of address, control, and data lines that can be used to communicate with external devices. Enthusiasts and a variety of third-party companies make use of this facility to create a wide range of add-ons for the ZX81.
The EdgE connEctOr OR extErnal iNterFacE At the rEaR oF the Zx81 is an exTension Of The Main PRintED circuIt Board. this proViDes a set Of adDresS, cONtRol, And data Lines thaT cAN be UsED TO CoMMuNicatE wiTH eXtErNaL deViceS. enthuSiasts anD A VARieTy oF third-paRTY COmPanIEs maKe use oF THiS fAcIlIty to CReate a wide RanGe OF add-ons fOr thE Zx81.