Canvas: 40w x 24h character codes (80w x 72h 'pixels')
Colours: 7 (and black)
Broadcast Teletext Specification is here.
The Enhanced Teletext Specification document is here.
Did you know?[Ceefax and ORACLE] were originally incompatible; Ceefax displayed pages of 24 lines with 32 characters each, while ORACLE offered pages of 22 lines with 40 characters each. In other ways the standards overlapped; for instance, both used 7-bit ASCII characters and other basic details. In 1974 all the services agreed a standard for displaying the information. The display would be a simple 40 × 24 grid of text, with some graphics characters for constructing simple graphics. The standard did not define the delivery system, so both Viewdata-like and Teledata-like services could at least share the TV-side hardware (which at that point in time was quite expensive).