AT&T DMD 5620 Terminal Emulation - macOS implementation
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DMD 5620.xcodeproj
DMD 5620.xcworkspace
DMD 5620

DMD 5620 Emulator for the Macintosh

The AT&T / Teletype DMD 5620 terminal was a portrait display, programmable windowing terminal produced in 1984. It came out of earlier research pioneered by Rob Pike and Bart Locanthi Jr., of AT&T Bell Labs.

Several iterations of terminals based on Pike and Locanthi's work were produced. The prototypes and early models were based around a Motorola 68000 CPU, and are better known as jerq or Blit terminals. The commercialized version produced jointly by the Teletype Corporation and AT&T in 1984 was called the DMD 5620, and used a Western Electric WE32100 CPU.

The goal of this project is to provide a highly accurate emulation of the DMD 5620 terminal.

Download from the Mac App Store



  • Added a new visual effect: You can optionally enable simulation of phosphor permanence on the screen. This makes the terminal much more realistic looking, at the expense of using more CPU to render the images.


  • Fixed a bug that caused the app to crash when custom colors were set using non-RGB colorspace.


  • Added clipboard paste functionality, accessible from the "Edit" menu, or from the keyboard shortcut Command-V.


  • Fixed a bug that prevented terminal settings from being saved on quit.
  • Added a "Reset" menu item.


  • Upgraded to dmd_core 0.6.3 to fix video RAM and DUART bugs.
  • Fixed a timing bug in downloading programs to the terminal using 32ld on 3B2 hosts.


Copyright 2018, Seth J. Morabito <>

Licensed under the MIT license.

Additional Copyright

This project uses the CocoaAsyncSocket library ( CocoaAsyncSocket is copyright 2017, Duesty LLC and provided through a BSD license.