DDT
\dˌiːdˌiːtˈiː], \dˌiːdˌiːtˈiː], \d_ˌiː_d_ˌiː_t_ˈiː]\
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By Princeton University
By DataStellar Co., Ltd
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A polychlorinated pesticide that is resistant to destruction by light and oxidation. Its unusual stability has resulted in difficulties in residue removal from water, soil, and foodstuffs. This substance may reasonably be anticipated to be a carcinogen: Fourth Annual Report on Carcinogens (NTP-85-002, 1985). (From Merck Index, 11th ed)
By DataStellar Co., Ltd
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1. Generic term for a program that assists in debugging otherprograms by showing individual machine instructions in areadable symbolic form and letting the user change them. Inthis sense the term DDT is now archaic, having been widelydisplaced by "debugger" or names of individual programs like"adb", "sdb", "dbx", or "gdb".2. Under MIT's fabled ITS operating system, DDT (runningunder the alias HACTRN) was also used as the shell or toplevel command language used to execute other programs.3. Any one of several specific debuggers supported on earlyDEC hardware. The DEC PDP-10 Reference Handbook (1969)contained a footnote on the first page of the documentationfor DDT that illuminates the origin of the term:Historical footnote: DDT was developed at MIT for thePDP-1 computer in 1961. At that time DDT stood for "DECDebugging Tape". Since then, the idea of an on-line debuggingprogram has propagated throughout the computer industry. DDTprograms are now available for all DEC computers. Since mediaother than tape are now frequently used, the more descriptivename "Dynamic Debugging Technique" has been adopted, retainingthe DDT abbreviation. Confusion between DDT-10 and anotherwell known pesticide, dichloro-diphenyl-trichloroethane(C14-H9-Cl5) should be minimal since each attacks a different,and apparently mutually exclusive, class of bugs. (The "tape" referred to was, incidentally, not magnetic butpaper.) Sadly, this quotation was removed from later editionsof the handbook after the suits took over and DEC becamemuch more "businesslike".The history above is known to many old-time hackers. Butthere's more: Peter Samson, compiler of the original TMRClexicon, reports that he named "DDT" after a similar tool onthe TX-0 computer, the direct ancestor of the PDP-1 built atMIT's Lincoln Lab in 1957. The debugger on thatground-breaking machine (the first transistorised computer)rejoiced in the name FLIT (FLexowriter Interrogation Tape).
By Denis Howe
Word of the day
Dopamine Acetyltransferase
- An enzyme that catalyzes the of groups from acetyl-CoA to arylamines. They have wide specificity for aromatic amines, particularly serotonin, and can also catalyze acetyl transfer between arylamines without CoA. EC 2.3.1.5.