IBM is going after online retailer Amazon.com for infringement on patents that go back as far as the 1980s.

Big Blue says that Amazon hasn't licenced the IBM-patented technology on which it is runs, including product recommendations, advertising, and data storage. One of the patents, called “Ordering Items Using an Electronic Catalog”, was filed sometime in the 1980s.

IBM says that it's tried to get Amazon to the table to negotiate licencing deals that “hundreds” of other companies have agreed to, but Amazon has refused. The computer company has now filed suit in two Texas courts.

It's not known how much IBM is seeking in damages, but John Kelly III, IBM's senior VP for intellectual property, said, “We are not unreasonable people”, in reply to an AP reporter's questions.

Patents are big business for IBM, which spends $6 billion a year in R&D, and earns up to $1 billion a year in royalties.