February 13, 2026
Green screens, hot takes
An open replacement for the IBM 3174 Establishment Controller
Open DIY box revives vintage IBM screens; nostalgia floods in, purists nitpick
TLDR: An open project called oec lets vintage IBM 3270 terminals connect to a mainframe emulator with basic features today. The crowd is split between purists wanting exact 3174 emulation, collectors swooning over retro hardware, and jokers dreaming of Costco shelves—proof old tech still sparks big feelings.
Everyone’s buzzing about oec, a DIY, open replacement for IBM’s old 3174 controller—the box that made classic green-screen terminals talk to big iron mainframes. It’s early days, but it already handles TN3270 (a network flavor for mainframes) and VT100 (old-school terminal style), and can juggle up to eight terminals through a multiplexer. That’s the news. The drama? The community instantly split into camps. One side wants pixel-perfect authenticity, with skissane wondering, “how hard would it be to write an emulator to run the actual 3174 software?” The other side cheers the pragmatic “it works, ship it” energy, thrilled that it runs on Python and talks to the Hercules emulator. Retro romantics swooned as dare944 confessed the “beautiful 3278 terminal pegs my retro-envy needle,” turning the thread into a mini fanclub for chunky keyboards and amber monitors. Meanwhile, the jokesters showed up with retail fever: farklenotabot pitched “sell this to Costco and Best Buy”, imagining green screens stacked next to air fryers. There’s also a low-key grumble about VT100 not working on Windows—cue the “install Linux” memes. In short: nostalgia vs purism vs practicality, with plenty of humor and a surprising amount of love for cables, coax, and clacky keys.
Key Points
- •“oec” is an open project to replace the IBM 3174 Establishment Controller for connecting IBM 3270 terminals to hosts like the Hercules emulator.
- •It supports TN3270 (with Extended Data Stream), basic TN3270E, device name (LU) negotiation, SSL/TLS, and provides VT100 emulation.
- •Only CUT-type terminals are supported; tested models include IBM 3179, 3278-2, 3472, 3483-V (InfoWindow II), and Memorex 2078.
- •Multiple Logical Terminals (MLT) and up to eight terminals are supported via an IBM 3299 multiplexer, requiring a compatible interface with recent firmware.
- •Setup requires Python 3.8+, a virtual environment is recommended, dependencies are installed with pip, and example commands are provided for TN3270 and VT100 modes.