Sakai Toshiyuki was born on October 19, 1924 in Osaka Pref. He graduated from the Department of Electrical Engineering, Kyoto University in 1947. After graduating, he was engaged in research related to microwave technology for five years as a special research associate with Graduate School of Kyoto University. In the late 1950s, he joined the University's newly-established laboratory on wire tele-communication, and started his research on communication engineering and digital computers under the supervision of Maeda Ken-ichi.

In 1959, Maeda received a 2-year project grant from the Ministry of Education and Sakai took on a leadership role in designing and developing the Kyoto university Digital Computer KDC-1 (prototype of the commercially available computer HITAC102B). He revised transistor and diode circuits employed in the Electrotechnical Laboratory's ETL Mark V. Together with his colleagues Kiyono Takeshi, Hagiwara Hiroshi and Yajima Shuzo, he devoted his energies at the computer center toward system management of the KDC-1 in order to expand its use among all university users until it was replaced five years later. His efforts were even applied in areas such as computer room layout design, system management, software development and document publishing.

Sakai chose speech, the information medium of telephones, as his basic area of research in digital technology, carrying out joint research activities with NEC. In addition to speech recognition, he further expanded his research area to cover character and document recognition. He is highly regarded as a pioneer in the field of pattern recognition research and development.

From 1960 Sakai was Professor of Electrical Engineering at Kyoto University, managing the Lab. of Wire Tele-communication, and from 1970, he held a professorship in the Department of Information Science and established the Lab. of Information Science Fundamentals. At this early stage in his career, he had already published numerous papers and books on computer and information technology and was actively involved as an important and leading figure in academic societies as well as in the promotion of research activities with various industries.

In 1967 Sakai installed NEAC2200/200 which was dedicated for use in his laboratory. The installation of a computer dedicatedly used at a research laboratory was probably the first case in Japanese universities. He applied this system to a wide array of online real-time applications covering image and speech processing involving a vast amount of data and interactive communication between man and machine. Utilizing the unique features of the character machine of NEAC2200/200, this system was made possible through parallel data transmission and control schemes with 54 coaxial cables. The system was completed through joint research with NEC and his staff members Doshita Shuji and Nagao Makoto.

The system was demonstrated at the Sumitomo Dowakan exhibition building during the EXPO'70 held in Osaka as the show for participant's face outline extraction and character judgement. He expanded the system to a computer complex which was used on an open-shop basis and involved heterogeneous computers, such as the NEAC2200, MACC7/F, MELCOM70, TOSBAC40 and FACOM U200. The communication protocol for different computers was based on the channel connection specification called OLA. This marked the first time in the world that high-speed processing was achieved through cooperative enhancement performed by hardware and software and laid the foundation for providing sufficient power for multimedia applications.

In 1973 Sakai developed a star-type computer network named KUIPNET(Kyoto University Information Processing Network) which could connect to various terminal computers distributed in the department through IMP (Interface Message Processor NEAC3200/50=the same model as Honeywell DDP516 used in ARPANET), and could switch the connection between a terminal computer and the central computer NEAC2200/250, according to various purposes of speech and image processing. Employment of this system made it possible to conduct research more efficiently and enabled 24-hour use. In 1983 the central computer NEAC was replaced with the MS190. This allowed various personal computers and workstations to be connected to the KUIPNET with far greater efficiency than the previous system, and provided a wider communication band width for the input and output of image and speech.

From 1985 through 1988, Sakai received a special grant from the Ministry of Education and Culture and built the Integrated Media Environment System (IMES).This system was the first of its kind in the world, in which more than 30 digital equipments and terminals were successfully connected with the help and cooperation of twelve companies, including some from abroad.@However, due to limited functioning and the narrow communication band-width supplied by terminal equipment used in those days, the system did not become a completely distributed and parallelized network system.

From 1976 to 1981, Sakai was engaged in building a wide area network called N-1 which had the capability to connect the Data Processing Centers of seven major national universities in order to perform various services such as file transfer. This work was pursued jointly by Kyoto University, The University of Tokyo and NTT.

Upon his retirement from Kyoto University at the age of 63, Sakai was invited by Ryukoku University (the third new campus located in Otsu City) to the post of Dean of the Faculty of Science and Technology. With the support of IMES companies, he established RINS (Ryukoku University Information Network System) for use in education and research as well as office management and library support. RINS served as the connection for the IBM main frame computer, Sony and NEC workstations (approximately 100 systems) and other types of PCs and workstations. During the successive five years after the faculty was established, RINS had provided without any hindrance various daily services for student education (400 students had entered to the faculty each academic year). All the learning materials used at every class on computer experiments and exercises had been archived for half a year and could be freely used by students according to their progress of learning.

Sakai's focus in the early 1970s on the integrated research of multimedia and networking as opposed to traditional numerical computation is evidence of his keen insight into these now flourishing technologies. All of the research Sakai has conducted on multimedia and networks during the dawn of the Information Technology Age are truly pioneering works. These numerous and significant contributions in original research, education and social activities were recognized by the Japanese government, which honored Sakai as Person of Cultural Merits in 1996 for his distinguished services in the field of culture.

Sakai died on August 16, 2017.