The edge connector on the rear of the Electron exposes all address and data bus lines from the CPU, including the upper eight bits of the address bus, in contrast to the limited selection available via the BBC Micro's expansion ports, with the One Megahertz Bus as the principal mechanism for general purpose expansion on the BBC Micro only providing the lower eight bits of the address bus. In addition, various control signals provided by the CPU and ULA are exposed via the Electron's expansion connector.