This is a Master Series issue 1 motherboard but without UHF modulator, analogue port, D7002 ADC, RS423 port, cassette port and circuitry, cassette relay, audio output, serial processor, 6850, two ROM sockets, disc interface including 1770, and modem connector.

On a standard Master ET, all the front IDC connectors would be missing, as would the user VIA. Acorn ADFS has been added to the only available ROM socket and the machine sports an EPROM containing the cut-down ET system ROM.