There are 3 chips that make up the Tate DES IC's, the Detector Chip and the 2 Matrix Multiplier chips - the detector chip from Exar is RA402 and the Matrix Multiplier chips are RA404.
Dolby also used the National Semiconductor Tate IC's in the very first Cat-150's, which were the first produced chips and defective, requiring extensive outboard circuitry to make them work. Their numbers are LM1852N for the detector chip and the 2 matrix multiplier chips are LM1853N. As soon as the Exar IC's became available, Dolby abandoned the National chips and went with Exar Tate II chips, which performed much better. I don't think they changed the Cat-150 designations though.
The chips have heat-sinks on them so I've never seen what they look like "naked". Dolby added large amounts of outboard circuits to make them work with the Dolby Surround system, slowing down their performance to better deal with the problems of optical film sound and also to make them decode in a 'diamond' speaker layout instead of the 'square' quad of SQ.
The the CAT-150E board used the Sanyo Pro-Logic chip but didn't use the built-in VCA's - instead, Dolby used very high-quality outboard VCA's on the E board and it has the best performance of any 150, with more headroom and dynamic range - there is a CAT-150D, but I'm not sure which chip it used. The Tate IC's were used on the A-B and C Cat-150 boards. The original CAT-116 boards used the Sansui Vario-Matrix IC's, but only for the surround channels - the front 3 channels were decoded separately with a gain-riding logic and the Cat-116 ONLY decoded the surround channel, but it performed so badly with dialog leakage that Dolby quickly abandoned the Vario-Matrix IC's for the Tate system. Anyway, on the CAT-150 you'll need to determine if the chips are the National chips or the Tate II Exar IC's.
You might want to contact Dolby about it - I'm sure someone there could help you out. From reading the schematics of the various processors like the CP-200, the Exar IC's were implemented pretty quickly.
