Fernando Jose "Corby" Corbato, the US inventor of the password and a key figure in the development of personal computers, has died aged 93.
Corbato died on Friday at a nursing home as a result of complications from diabetes, the Massachusetts Institute of Technology says.
"Decades before the existence of concepts like cybersecurity and the cloud, Corbato led the development of one of the world's first operating systems," MIT said in a statement.
"His Compatible Time-Sharing System (CTSS) allowed multiple people to use a computer at the same time, greatly increasing the speed at which programmers could work. It's also widely credited as the first computer system to use passwords."
In the 1960s, when the MIT scientist worked on CTSS, researchers sometimes had to wait until the next day to access the output of programs, an inefficient process that angered Corbato.
Instead of a big computer, Corbato used an electric typewriter connected to an electronic base. The central processing unit then could handle one operation at a time, through a "supervising program", but it delivered faster output and moved smoothly from one task to another.
The need for personalising accounts prompted the computer scientist to invent a personal password for each user, something that was considered one of the first steps of the security procedure.
CTSS also used an early version of email and instant messaging, and paved the way for a project called Multics, which helped inspire the Unix operating system.
Australian Associated Press