Port 149: AED 512 Emulation Service — A Color Graphics Ghost

Port 149 is assigned to the AED 512 Emulation Service¹. It is a well-known port, registered with IANA for both TCP and UDP. The protocol allowed remote control of the AED 512, a full-color graphics display terminal built by Advanced Electronics Design, Inc. of Sunnyvale, California.

No one uses port 149 anymore. The terminals are gone. The company is gone. The protocol serves nothing. But the port assignment remains in the IANA registry, filed under the contact name Albert G. Broscius at the University of Pennsylvania's Department of Computer and Information Science¹.

The AED 512

In 1981, most computer screens displayed monochrome text. Green phosphor on black, maybe amber if you were lucky. The AED 512 was something else entirely: a full-color graphics display system with 512 x 512 resolution, multiple memory planes, direct video memory access, joystick input, and crosshair cursor support²³.

Advanced Electronics Design started in the early 1970s as a floppy disk and storage manufacturer before expanding into graphics terminals in the late 1970s³. Their machines found an audience in VLSI (Very Large Scale Integration) chip design work, supported by major CAD vendors including VTI and UC Berkeley's tools³. The AED 767, their second-generation terminal, was a 6502-based system that could theoretically support four graphics screens simultaneously³. Several hundred units were sold.

The AED 512 Emulation Service on port 149 allowed these terminals to be controlled over a network, enabling remote access to their graphics capabilities. In an era when graphics hardware was expensive and scarce, being able to share a color display terminal across a network was genuinely valuable.

What Happened

IBM released the Color Graphics Adapter in 1981. CGA was crude by the AED 512's standards (just 320 x 200 in four colors compared to the AED's 512 x 512 in full color), but it was cheap, it was everywhere, and it was built into the machine that was eating the world. The dedicated graphics terminal market collapsed.

Advanced Electronics Design maxed out at around 200 employees before the decline began³. The company's assets were sold to a firm in San Diego in the mid-1980s. AED, as one historian put it, "sank without a trace"³.

Not entirely without a trace. Engineering teams that left AED went on to found Jupiter Systems and Parallax Graphics³. The AED 512 documentation survives in the Internet Archive². And port 149 sits in the IANA registry, quietly assigned to a service that no machine on Earth is running.

Port 149 Today

This port belongs to the well-known range (0 through 1023), which means it was assigned through IETF review or IESG approval⁴. On Unix-like systems, binding to a well-known port requires superuser privileges.

In practice, port 149 is silent. No modern software listens on it. No scanning tools flag it as interesting. It occupies a strange category: officially assigned, functionally abandoned.

How to Check What Is Listening on Port 149

On most systems, nothing will be. But if you want to verify:

Linux:

sudo ss -tlnp | grep :149
sudo netstat -tlnp | grep :149

macOS:

sudo lsof -iTCP:149 -sTCP:LISTEN

Windows:

netstat -an | findstr :149

If something is listening on port 149, it is almost certainly not running the AED 512 Emulation Service. Investigate it.

Why Abandoned Ports Matter

The IANA registry contains hundreds of ports like 149: assigned decades ago to protocols and services that no longer exist. They are not reclaimed. They are not reassigned. They sit in the registry like reserved parking spaces for cars that will never return.

This is by design. Reassigning a port could break legacy systems that still reference the old assignment. The cost of a permanently occupied port number is low (there are 65,535 of them), while the cost of a collision between old and new services sharing a port is high. So port 149 stays assigned to AED 512 Emulation, and it will stay assigned to AED 512 Emulation indefinitely.

The registry is honest this way. It does not pretend these services still run. It simply records that someone once needed this port badly enough to register it. That record is its own kind of history.