Acorn
Teletext
Adapter
This is the underside of the Acorn Teletext Adapter. It displays a number of the features found underneath the BBC Model B such as the four rubber feet, a serial number ticket, ventilation slots for the power unit and a cut-out section.
A length of 34-way ribbon cable emerges from the cut-out section for connection to the 1 MHz Bus of the BBC computer or to the 1 MHz Bus Out socket of a device already connected to the BBC to form a "daisy-chain" of peripherals.
The Teletext Adapter does not have a 1 MHz Out socket because it was designated by Acorn as the last device in the 1 MHz bus chain of add-ons. Apparently it has terminating resistors on board.