2014-04-26 10:52:28 -04:00
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DDT
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2014-04-26 11:54:15 -04:00
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/DDT/ , n. [from the insecticide para-dichloro-diphenyl-trichloroethene] 1.
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Generic term for a program that assists in debugging other programs by
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showing individual machine instructions in a readable symbolic form and
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letting the user change them. In this sense the term DDT is now archaic,
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having been widely displaced by debugger or names of individual programs
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like adb , sdb , dbx , or gdb. 2. [ITS] Under MIT's fabled ITS operating
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system, DDT (running under the alias HACTRN, a six-letterism for Hack
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Translator ) was also used as the shell or top level command language used
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to execute other programs. 3. Any one of several specific DDTs (sense 1)
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supported on early DEC hardware and CP/M. The PDP-10 Reference Handbook
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(1969) contained a footnote on the first page of the documentation for DDT
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that illuminates the origin of the term: Historical footnote: DDT was
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developed at MIT for the PDP-1 computer in 1961. At that time DDT stood for
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DEC Debugging Tape. Since then, the idea of an on-line debugging program has
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propagated throughout the computer industry. DDT programs are now available
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for all DEC computers. Since media other than tape are now frequently used,
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the more descriptive name Dynamic Debugging Technique has been adopted,
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retaining the DDT abbreviation. Confusion between DDT-10 and another well
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known pesticide, dichloro-diphenyl-trichloroethane C 14 H 9 Cl 5 should be
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minimal since each attacks a different, and apparently mutually exclusive,
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class of bugs. (The tape referred to was, incidentally, not magnetic but
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paper.) Sadly, this quotation was removed from later editions of the
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handbook after the suit s took over and DEC became much more businesslike.
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The history above is known to many old-time hackers. But there's more: Peter
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Samson, compiler of the original TMRC lexicon, reports that he named DDT
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after a similar tool on the TX-0 computer, the direct ancestor of the PDP-1
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built at MIT's Lincoln Lab in 1957. The debugger on that ground-breaking
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machine (the first transistorized computer) rejoiced in the name FLIT
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(FLexowriter Interrogation Tape). Flit was for many years the trade-name of
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a popular insecticide.
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