The story
Attachmate Corporation
Attachmate was founded in 1982 by Frank W. Pritt. It focused initially on the IBM terminal emulation market, and became a major technology employer in the Seattle area.
KeaTerm
KEAsystems' KEAterm products were PC software packages that emulated some of Digital Equipment Corporation's VT terminals, and facilitated integrating Windows-based PCs with multiple host applications. These included KEAterm VT340 and VT420 terminal emulators, and KEA X X terminal software).
KEA was acquired by Attachmate.
DCA IRMA
Another acquisition was Digital Communications Associates (DCA), makers of IRMA line of terminal emulators, INFOconnect, Crosstalk communications software, and OpenMind collaborative software). DCA was also known for its 3270 IRMA hardware product (used for SDLC), and ISCA SDLC hardware adapters. They also supported driver downloads.
Extra!
The Attachmate Extra! family of terminal emulator packages was built to include 3270, 5250 and VT100.
From Wikipedia’s article on Attachmate, shared under CC BY-SA 4.0.4