In 1924 the Navy had only two operators who knew Japanese Morse. Safford contracted with the Underwood Typewriter Company to build special typewriters that printed kana. The keys were cleverly arranged so that, at least for the lowercase character set, the kana keys were located in the same place as the corresponding International Morse letter would be on a regular typewriter. When an operator heard _._., he would just hit the key where "C" would normally be, and the machine would print the kana for NI. The machines cost a whopping $160 apiece, and only about forty were acquired, paid for out of the Office of Naval Intelligence slush fund...

Stephen Budiansky,
BATTLE OF WITS: THE COMPLETE STORY OF CODEBREAKING IN WORLD WAR II,
A Touchstone Book, Simon & Schuster, New York (2002).
Pages 36-37.

Famous among communications intelligence veterans, the RIP-5 was a machine that greatly simplified interception of Japanese transmissions. Though its acrynym stood for "Registered Intelligence Publication," the RIP-5 consisted of a typewriter modified to reproduce the kana for which Japanese Morse code letters stood. It had been developed at the initiative of Laurence Safford in 1924, paid for from the ONI slush fund, and made by the Underwood Typewriter Company, whose officials worked out the mechanism in cooperation with Safford. The first ones cost $160 each. Intercept veterans recall using RIP-5s in Shanghai as early as 1929. Operators could record Japanese radio transmissions more easily, often faster than Imperial Navy radiomen could draw the kana themselves...

John Prados
COMBINED FLEET DECODED - THE SECRET HISTORY FO AMERICAN INTELLIGENC AND THE JAPANESE NAVY IN WORLD WAR II.
Random House, New York (1995).
Page 82.

See publication #607 from the U.S. Naval Cryptologic Veteran's Association, "Ships Store."

NARA RG 38, RIP (Radio Intelligence Publications) Finding Aid
Archives II in College Park, MD