GENERAL DESCRIPTION
The SAA5250 is a CMOS Interface for Data Acquisition and Control (CIDAC) designed for use in conjunction with the Video Input Processor (SAA5230) in a multi-standard teletext decoder. The device retrieves data from a user selected channel (channel demultiplexer), as well as providing control signals and consecutive addressing space necessary to drive a 2 K bytes buffer memory.

The system operates in accordance with the following transmission standards:
• French Didon Antiope specification D2 A4-2 (DIDON)
• North American Broadcast Teletext specification (NABTS)
• U.K. teletext (CEEFAX)

Features
• 7,5 MHz maximum conversion rate
• Three prefixes; DIDON, NABTS and U.K. teletext (CEEFAX)
• Mode without prefix
• Internal calculation of the validation (VAL) and colour burst blanking (CBB) signals, if programmed
• Programmable framing code and channel numbers
• Error parity calculation or not (odd parity)
• Hamming processing of the prefix byte
• Full channel or VBI reception
• Slow/fast mode (detection of page flags or not)
• Maximum/default format up to 63 bytes
• Addressing space of 2 K bytes of the static memory
• Multiplexed address/data information is compatible with Motorola or Intel microcontrollers
• CIDAC is ‘MOTEL’ compatible