Digital Research CP-M-86 for the IBM Personal Computer Version 1

Dynamic Debugging Technique (DDT) is a series of debugger programs originally developed for

Digital Equipment Corporation Digital Equipment Corporation (DEC ), using the trademark Digital, was a major American company in the computer industry from the 1960s to the 1990s. The company was co-founded by Ken Olsen and Harlan Anderson in 1957. Olsen was president unt ...

(DEC) hardware, initially known as DEC Debugging Tape because it was distributed on

paper tape Five- and eight-hole punched paper tape Paper tape reader on the Harwell computer with a small piece of five-hole tape connected in a circle – creating a physical program loop Punched tape or perforated paper tape is a form of data storage ...

. The name is a pun on the insecticide

DDT Dichlorodiphenyltrichloroethane, commonly known as DDT, is a colorless, tasteless, and almost odorless crystalline chemical compound, an organochloride. Originally developed as an insecticide, it became infamous for its environmental impacts. ...

. 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. Early versions of

Digital Research Digital Research, Inc. (DR or DRI) was a company created by Gary Kildall to market and develop his CP/M operating system and related 8-bit, 16-bit and 32-bit systems like MP/M, Concurrent DOS, FlexOS, Multiuser DOS, DOS Plus, DR DOS and ...

CP/M CP/M, originally standing for Control Program/Monitor and later Control Program for Microcomputers, is a mass-market operating system created in 1974 for Intel 8080/ 85-based microcomputers by Gary Kildall of Digital Research, Inc. Initial ...

and

CP/M-86 CP/M-86 was a version of the CP/M operating system that Digital Research (DR) made for the Intel 8086 and Intel 8088. The system commands are the same as in CP/M-80. Executable files used the relocatable .CMD file format. Digital Research als ...

kept the DEC name DDT (and DDT-86 and DDT-68K) for their debugger, however, now meaning "Dynamic Debugging Tool". The CP/M DDT was later superseded by the ''

Symbolic Instruction Debugger Symbolic may refer to: * Symbol, something that represents an idea, a process, or a physical entity Mathematics, logic, and computing * Symbolic computation, a scientific area concerned with computing with mathematical formulas * Symbolic dynamic ...

'' (SID, ZSID, SID86, and GEMSID) in DR DOS and

GEM A gemstone (also called a fine gem, jewel, precious stone, or semiprecious stone) is a piece of mineral crystal which, in cut and polished form, is used to make jewelry or other adornments. However, certain rocks (such as lapis lazuli, opal, a ...

. In addition to its normal function as a debugger, DDT was also used as a top-level command shell for the

Massachusetts Institute of Technology The Massachusetts Institute of Technology (MIT) is a private land-grant research university in Cambridge, Massachusetts. Established in 1861, MIT has played a key role in the development of modern technology and science, and is one of the ...

(MIT)

Incompatible Timesharing System Incompatible Timesharing System (ITS) is a time-sharing operating system developed principally by the MIT Artificial Intelligence Laboratory, with help from Project MAC. The name is the jocular complement of the MIT Compatible Time-Sharing System ...

(ITS)

operating system An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs. Time-sharing operating systems schedule tasks for efficient use of the system and may also in ...

; on some more recent ITS systems, "PWORD"—which implements a restricted subset of DDT's functionality—is run first and is overlaid with DDT as soon as the user logs in. DDT could run and debug up to eight processes (called "jobs" on ITS) at a time, such as several sessions of 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").

Guy L. Steele Guy Lewis Steele Jr. (; born October 2, 1954) is an American computer scientist who has played an important role in designing and documenting several computer programming languages and technical standards. Biography Steele was born in Missouri ...

wrote a filk poem parody of

Edgar Allan Poe Edgar Allan Poe (; Edgar Poe; January 19, 1809 – October 7, 1849) was an American writer, poet, editor, and literary critic. Poe is best known for his poetry and short stories, particularly his tales of mystery and the macabre. He is wide ...

's " The Raven," entitled ''The HACTRN''.

DEC-10/DEC-20 DDT

DDT (Dynamic Debugging Technique), as implemented on the

DECsystem-10 Digital Equipment Corporation (DEC)'s PDP-10, later marketed as the DECsystem-10, is a mainframe computer family manufactured beginning in 1966 and discontinued in 1983. 1970s models and beyond were marketed under the DECsystem-10 name, especi ...

& DECSYSTEM-20 allowed references to symbols within the programming being debugged. This feature loaded symbols from the .EXE executable file; a special version named SDDT used symbols from the running monitor and allowed system programmers to "peek" inside.

References

External links

DDT Command List
for a freeware version written in portable C
ITS 1.5 Reference Manual
-(Artificial Intelligence Memo No. 161A)
ITS: Luser's Guide

The Great Quux Poem Collection
-(See especially the notes to the poem ''The HACTRN'') {{Digital Research Debuggers Digital Equipment Corporation CP/M Command shells

DEC-10/DEC-20 DDT

See also

References

External links