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9 October 2022 Update

It is likely that this repository should now be considered abandoned. Developing for macOS is painful these days, and keeping up with changes on the platform is difficult and time consuming.

If you would like to maintain this package, please let me know. Otherwise, it should be considered unmaintained.

The GTK+ native application works very well on macOS now, and should be used instead.

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.



  • 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.