After retiring the floppy disk in March, Sony has halted the manufacture and distribution of another now-obsolete technology: the cassette Walkman, the first low-cost, portable music player.The final batch was shipped to Japanese retailers in April, according to IT Media. Once these units are sold, new cassette Walkmans will no longer be available through the manufacturer.The first generation Walkman (which was called the Soundabout in the U.S., and the Stowaway in the UK) was released on July 1, 1979 in Japan.