Desktop Cyber (dtCyber) is a faithful emulation of the CDC hardware from the Mainframe era.

Many repositories exist and have fragmented over the years. Tom Hunter's repository was maintained in SubVersion form for most of its life and was periodically forked/branched/merged with other variants. This document contains the current “known” locations of the repositories and, to whatever extent is known, their lineage.

Upon the closure of the original ControlFreaks TWIKI, there emerged a number of parallel efforts to reconstitute the current state of dtCyber work. GitHub contains 4 repositories (as of this writing) by the following contributors

GitHub Repositories

Tom Hunter's repository was established using the now-defunct svn2github service. Because this instance no longer has any other active source, the file DtCyber-master-svn2github.zip has been created as an alternative source of the final version for storage/access on this site. Because the history may be important to some, DtCyber.svn2github.GIT.zip was also created as a static reproduction of the repository.

John Bradley's fork of the above repository is an in-tact copy of the SVN2GitHub copy.

Paul Koning's fork of dtCyber was built from a somewhat older instance of the dtCyber codebase. Its main purpose is to support the PLATO system at cyber1.org, which runs this version, but it is available to everyone, with open read access. Paul maintains his work in a Subversion repository. Paul's repository is maintained at

svn svn://akdesign.dyndns.org/dtcyber/trunk

Some features in this branch:

• Operator and DD60 console interfaces are in separate programs via TCP connections (allowing remote operators).
• A truly strange hack to allow access to the host “socket” service via non-standard CPU instructions.
• NIU (PLATO terminal interface) support.
• Dual CPU support.
• In the “vhdl” subdirectory there is a basically complete and somewhat functional gate level VHDL model of the 6600, constructed from the wire lists. (The wire lists text is also there.)
• In the “spice” subdirectory there is a rough approximation of a SPICE model (for ngSPICE) for the DD60 console display.

Kevin Jordan's branch of the dtCyber codebase is one of the most complete and best-maintained after Tom Hunter's retirement from the project. Kevin has done a terrific job of enhancing the simulator and has added features including:

• Dual CPU support
• Cyber 875 support with memory size up to 4M words (32M bytes)
• CDCNet MDI and TCP/IP support
• CCP LIP (Link Interface Program) support enabling RHP networking between NOS 2 systems
• NJE support compatible with Hercules IBM mainframe emulator
• RJE support compatible with Hercules IBM mainframe emulator
• 6671 mux support, enabling RJE with MODE4 on KRONOS and NOS 1
• 3255/311 DSA support, enabling TIELINE on NOS 1
• Cray Station interface support compatible with Andras Tantos' Cray X-MP emulator
• NIU support enabling PLATO on NOS 1
• Automated cartridge tape functionality with StorageTek 4400 emulation
• Operator interface automation enabling scripting of Cyber console interactions and peripheral device management
• Remote console interface with web-based and text-mode console emulation
• Web-based terminal emulation of VT-100, Tektronix 401x, PLATO/CYBIS, and IBM 3270 terminals
• Web-based and command line RJE station emulation
• Pre-built, ready-to-run packages for NOS 2.8.7, NOS 1.3, KRONOS 2.1, NOS/BE, HUSTLER, and COS operating systems
• and more

Dale Sinder's and William Schaub's repositories appear to be a complete baseline version of Tom's final distribution.

Steve Zoppi's repository is a fork of the Jordan repository and all features are built upon Kevin's work.

Extensions include:

• Enhanced Unit Record device functionality
  • All UR devices support automatic end of job file closure and naming
  • Card Readers may have directories which emulate “input” and “output” hoppers
  • Card Punches support directories as “output” hoppers
  • Line Printers fully implement command codes for positioning and output using ANSI and ASCII command codes
• Enhanced Operator (dtcyber console) Interface
• Added Operational Status displays

In his original document, the following people were credited for the original work and support of dtCyber:

He also noted:

Please note that this list is probably incomplete and in no particular order. Sorry if I forgot you.

A special thank you goes to the man who was responsible for the design of Control Data Corporation's most successful large-scale computer, the CDC 6600 system.

Seymour Cray was born in 1925 in Chippewa Falls, Wisconsin; he died in 1996 in Colorado Springs, Colorado, from injuries suffered in a car accident.