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