8 Oct
2008
8 Oct
'08
1:27 p.m.
BBC Microcomputer, not surprisingly, for which there
were at least two
teletext adapters (the original Acorn one and later one from a third
party company called Morley Electronics). The teletext adapters connect
to a BBC Micro via its 1MHZ expansion bus. Most of the BBC telesoftware
Minor correction. The Acorn teletext adapter, which used the SAA5020 etc
chipset did, indeed connect via the 1MHz bus. But the (IMHO) nicer Morley
one connected to the User Port. It had an I2C interface to an SAA5240
chip (this teletext decoder used the I2C bus mot only to select the page,
etc, but also allowed you to read/write the teletext page memory, so
transfering the page to the BBC micro was relatively easy). There was
also a CITAC (Computer Interface for Tuning and Control) chip on that I2C
bus (I forget which one was used), this was used to select the TV
channel, IIRC the Acorn one had 4 preset pots to select the channel, the
computer could then select one of 4 channels.
-tony