I believe they were the HK628 and UM3561 chips which were launched in the 1980s for toys. You can actually hear that alarm sound on some toys from that decade. They were simple chips that stored 8-16 preprogrammed sounds and the urban legend is that the car companies just kept the alarm demo sound (I think there were two different ones). The chips ended up everywhere: toys, care, appliances, industrial machinery, etc.