The page-printer stood beside the desk of the GY watch officer. It rapped out the intercept in an original and a carbon copy on yellow and pink teletype paper just like news on a city room wire-service ticker. … His chief target was the flag officers’ system, the Japanese Navy’s most difficult and the one in which it encased its most secret …
https://www.amazon.com/Codebreakers-Comprehensive-History-Communication-Internet/dp/0684831309