The Ampex 6500 Workstation functioned as an MS-DOS-based PC when it wasn’t acting as a terminal to a mainframe. It offered a wide range of communications protocols, including DEC VT-100 and IBM 3270.
Ampex is still in business and is known for its specialized digital storage systems used primarily in the defense industry.
Ampex 6500 Workstation (1984, workstation)
Base Configuration: two 5.25-inch floppy disk drives, integrated 12-inch monochrome monitor, keyboard, MS-DOS