The SDS-940 time sharing system had a DDT, which was the dynamic debugging
tool. 4000;g started your program at 4000 octal. I believe both MIT and UC
Berkeley worked on the implementation, so maybe the 940's DDT has roots in the
MIT implementation for the PDP 1.
[off topic, but SIMH includes a 940 simulator--] It is said that the 940
time-sharing system was the first commercial OS to allow users with no special
privileges to write and run assembly language programs.
If "mother of all demos" means nothing to you, start at
https://en.m.wikipedia.org/wiki/The_Mother_of_All_Demos. Regrettably, I knew
nothing about that demo when I worked on the NBS/NOAA/DOC-B 940 in the '70s
(with SIMH contributor Mark Emmer.
--Howard
Sent from my iPhone
> On Jan 21, 2016, at 14:41, Hittner, David T (IS)
> wrote:
>
> That was awesome, Tim. Thanks for the historical perspective on the removed
> pesticide disclaimer. ;-)
>
> And for certain systems, DDT was also the “DIBOL Debugging Tool”.
>
> Dave
>
> From: Simh [mailto:simh-boun...@trailing-edge.com] On Behalf Of Timothe Litt
> Sent: Thursday, January 21, 2016 2:27 PM
> To: simh@trailing-edge.com
> Subject: EXT :Re: [Simh] On {O,D}DDT
>
> On 21-Jan-16 11:53, Paul Koning wrote:
>
>
> On Jan 21, 2016, at 10:58 AM, Ethan Dicks wrote:
>
> On Wed, Jan 20, 2016 at 8:37 PM, Johnny Billquist wrote:
> ODT actually stands for On-line Debugging Tool, not Online Debugging
> Technique.
>
> I recall Octal Debugging Technique. Anyone else remember that definition?
>
> Things get interesting...
>
> The name ODT was derived from the TOPS-10 debugger DDT -- an obvious name in
> that era for something that gets rid of bugs, but officially it stood for
> "Dynamic Debugging Technique".
>
> ODT was much simpler, not offering symbolic debugging for one thing. So it
> got a different name, and since its I/O was pretty much just octal numbers,
> replacing "dynamic" by "octal" made sense.
>
> Then again, the DOS V9 manual says it's "On-line debugging technique". So do
> several RT11 manuals. Hm. Now I'm puzzled. I clearly remember "octal" and
> don't remember ever seeing "on-line". And sure enough, the header of the
> source code for RSTS "monitor ODT" (the kernel debugger) says "Octal
> debugging tool".
>
> So it looks like DEC wasn't consistent. On-line in some places, octal in
> others, and "technique" in the official documents I remember but "tool" at
> least internally (a more obvious word to use, certainly).
>
> paul
>
>
> Besides multiple technical writers, editors and product managers: there were
> multiple implementations - including some for non-DEC machines. I had a
> small part in DDT-11, and also implemented an ODT-clone on 8 and 16-bit uPs.
> ODT was, IIRC originally called Octal Debugging Technique, in a nod to DDT.
> Actually, there are two DDT-11s; one that runs on the -11 (used in ANF-10
> network nodes), and one that lives on a -10 (or -20) and remotely debugs the
> -11, and/or the 11's crash dumps. In fact, DDT-11 can be booted in exec mode
> on a KS10, and run PDP-11 diagnostics under simulation against real hardware.
> (Yes, I did that.)
>
> Of course, DDT was also an octal debugger (unless you changed the input or
> output radix) - and more capabie as it could deal with symbol tables, paging,
> and so forth. But ODT was only capable of debugging in octal. (A
> consequence of the PDP-11's 4KW minimal and 28K maximum memory size.) So
> that's what it was called. Someone in marketing decided that octal was too
> geeky, and that 'on-line' would sell better.
>
> Engineers being what we are (many students of human, as well as computer
> languages), pointed out that "technique" is how one uses a tool. But it's a
> stretch to call a tool a technique, at least in ordinary usage. So 'tool'
> was floated, but by that time ran against the couple of decades of
> established culture. (A very long time in technology-years.)
>
> An early DDT manual (~ 1970, but I've lost the colophon page) explains the
> DDT situation thusly:
>
> INTRODUCTION
> DDT-10 (for Dynamic Debugging Technique) * long page
>
> In very small print, smaller than I can reproduce here:
> *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 thoroughout 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 acronym. Confusion
> between DDT-10 and another well-known pesticide,
> dichloro-diphenyl-trichloroethane (C14H9Cl5) should be minimal since each
> attacks a different, and apparently mutually exclusie, class of bugs.
>
> Oddly enough, this paragraph subsequently caught the a
