Grammatik was the first grammar checking program developed for home computer systems. Aspen Software of Albuquerque, NM, released the earliest version of this diction and style checker for personal computers, in 1981. Grammatik was first available for a Radio Shack - TRS-80, and soon had versions for CP/M and the IBM PC. Reference Software of San Francisco, CA, acquired Grammatik in 1985. Development of Grammatik continued, and it became an actual grammar checker that could detect writing errors beyond simple style checking.