This is a Git conversion of the Subversion repository maintained by Paul Koning at the akdesign.org server. The purpose of the conversion is to make it easier to access and for the convenience of those more familiar with Git. The conversion was run on April 8, 2025. The Subversion server will be changed to read-only and at some later time be taken off-line.

This DtCyber fork was started many years ago before Tom Hunter moved to generally accessible source control and before he switched DtCyber to the GPL license.
The original license is still on this code; please read it. It is not a normal open source license; you will see it has some specific restrictions. I have not considered moving to an open source license (GPL would be the obvious choice) mainly because to do it properly would require the explicit consent of all the authors of the code here.

This fork fairly closely tracked Tom Hunter's main releases for some time, but not in recent years. Being more precise would require research. There are additional changes and new features made for the benefit of the PLATO system described at http://cyber1.org (the actual system's host is cyberserv.org).

Read only access is open to all. Please be aware of the license. It is not a standard open source license.

As with the Subversion repository, read/write access is by request. I have not carried over the access list of the Subversion repository; please contact me if you would like read/write access.

While not strictly DtCyber components, the repository also contains some other Cyber system related work.

The vhdl subdirectory contains the wirelists of the CDC 6600, from Bitsavers via OCR, and a gate level VHDL model constructed from these. That model is currently partly functional (PP and display controller work, the CPU not yet).

The spice subdirectory contains an attempt at creating a SPICE model (written for the open source "ngspice" version) of the DD60 display console. The intent is to model how it distorts the character plotting waveforms generated by the 6612 controller, resulting in the screen images familiar from old photos. At the moment the model is mostly written but it does not yet deliver anything close to the actual waveforms it should.