Re: [Simh] EXT :Re: On {O,D}DDT

[Hittner, David T (IS)]

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 attention of folks who had 
power, but not much humor.  So it was removed.  But it stuck with me, and is 
one of the few chemical formulae that I always have instantly to hand.

We also had *DDT products for various high-level languages, among them ALGDDT 
(Algol), PASDDT (Pascal), COBDDT (COBOL), FORDDT (FORTRAN) and SIMDDT (SIMULA). 
 But none retained the marvelously efficient, if not obvious at first glance, 
command syntax.  They all used DCL-like syntax, though they were long before 
that standardization effort: "examine", "break", etc.  I still think '/' is the 
obvious way to examine a variable... and $B to set a breakpoint.  My  fingers 
still rebel at verbose commands and carriage-returns when debugging on 'modern' 
machinery.

The other somewhat amusing thing is that DDT's adoption of the  (echoed as 
'$') key required a lot of explanation in the manuals, as various models of 
TeletypeTM caused keys located in the u

Re: [Simh] EXT :Re: On {O,D}DDT

[Howard Bussey]

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

Re: [Simh] EXT :Re: On {O,D}DDT

[Christian Gauger-Cosgrove]

On 21 January 2016 at 15:45, Howard Bussey  wrote:
> [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.
>
Less off topic: Is there any software to run on the 940 simulator?


> 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.
>
And for those who wish to *watch* the Mother of All Demos:



Best regards,
Christian Gauger-Cosgrove
-- 
Christian M. Gauger-Cosgrove
STCKON08DS0
Contact information available upon request.
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