The Commodore PET is among the first mass-marketed personal computers, including the Apple II and Tandy Radio Shack’s TRS-80.

The small screens show only a few lines of text at a time. But the fully assembled units allow more people to use them.

Dr. Raymond Damadian constructs the first whole-body magnetic resonance imaging (MRI) scanner.

The machine can look inside the body without surgery or X-rays. Instead, it uses magnetism and radio waves to produce pictures.