In the field of theoretical computer science, Yamada introduced the notion of real-time computability. As his colleague Aravind Joshi recalls:
This work was very positively reviewed not only in the computer science related journals but also in other theoretical journals such as the Journal of Symbolic Logic. Dr. Yamada’s work also played a key role in the early days of the field of computational complexity, by now a very well established area in computer science.
McNaughton, R.; Yamada, H. (1960). "Regular Expressions and State Graphs for Automata". IEEE Transactions on Electronic Computers. EC-9: 39–47. doi:10.1109/TEC.1960.5221603.
Yamada, H. (1962). "Real-Time Computation and Recursive Functions Not Real-Time Computable". IEEE Transactions on Electronic Computers. EC-11 (6): 753–760. doi:10.1109/TEC.1962.5219459.
Hisao Yamada: "A Historical Study of Typewriters and Typing Methods: from the Position of Planning Japanese Parallels", Journal of Information Processing, 2(4) (February 1980), pp. 175–202