Dynamic debugging technique: Difference between revisions

Revision as of 18:15, 13 August 2006

Revision as of 03:09, 21 September 2006

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: ''For other expansions of "DDT", see [[DDT (disambiguation)]].''

'''Dynamic Debugging Technique''', or '''DDT''', was the name of several [[debugger]] programs originally developed for [[Digital Equipment Corporation|DEC]] hardware, originallyinitially known as '''DEC Debugging Tape''' because it was distributed on [[paper tape]]). The first version of DDT was developed at [[MIT]] for the [[PDP-1]] computer in [[1961]], but newer versions on newer platforms continued to use the same name. After being ported to other vendor's platforms and changing media, the name was changed to the less DEC-centric version.

DDT is closely related to [[ODT]]. Both names were used for several different debuggers, but generally debuggers with the ODT name had more limited capabilities than DDT debuggers.

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As with other DEC tools, early [[CP/M]] kept the DEC name DDT for its debugger. DDT was later superseded by [[Symbolic Instruction Debugger|SID]].

In addition to its normal function as a debugger, DDT was also used as a top-level [[shell (computing)|command shell]] for the [[Massachusetts Institute of Technology|MIT]] [[Incompatible Timesharing System|ITS]] [[operating system]]; on some more recent ITS systems, it is replaced with a "PWORD" which implements a restricted subset of DDT's functionality. DDT could run and debug up to eight [[Job (software)|jobs]] at a time such as several sessions of [[Text Editor and Corrector|TECO]], and DDT could be run [[recursively]] - that is, some or all of those jobs could themselves be DDTs (which could then run another eight jobs, and so on). These eight jobs were all given unique names, and the usual name for the original and top-most DDT was "HACTRN" ("hack-tran"); thus [[Guy L. Steele]]'s famous [[filk]] poem ''The HACTRN''.

== External links ==

* [http://web.mit.edu/afs/net/project/cgw/src/ddt.68/ddt.cmds DDT Command List] for a freeware version written in portable [[C programming language|C]]

* [http://victor.se/bjorn/its/luser.php ITS: Luser's Guide]

* [http://www.csd.uwo.ca/~magi/personal/humour/Computer_Audience/The%20Great%20Quux%20Poem%20Collection.html The Great Quux Poem Collection] -(See especially the notes to the poem ''The HACTRN'')

[[Category:Debuggers]]