Never knew - if you see one at a yard sale, pick it up. From Crypto Museum:
Barbie™ Typewriter
Alphabet substitution cipher
The Barbie Typewriter E-118, is a low-cost electronic typewriter, developed as a children's toy by Mehano in Slovenia (formerly: Yugoslavia) and sold worldwide by Mattel (US). The E-118 is the latest model in the product line that started with the E-115. The electronic typewriter was the successor to the earlier purely mechanical Barbie typewriter models. It is little known that all electronic variants have a hidden built-in cryptographic capability that allows secret writing.
Although the E-118 is basically identical to the earlier models, the exterior has changed quite a bit over the years, probably to appeal more to young girls. Furthermore, the interior (especially the PCB) has been simplified several times in order to cut on production cost. Wilst the earlier models were all made at the Mehano factory in Slovenia, the latest one is assembled in China.
The E-118 consists of a plastic body with a 49-button keyboard, a plastic carriage that accepts common paper sheets, and a daisy wheel printer. It is aimed at children of 5 years and older.
Much more at the site including photos to recognize the various models as well as the keystrokes needed to enable encryption.
