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On 21-Jan-16 11:53, Paul Koning wrote:<br>
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<pre wrap="">On Jan 21, 2016, at 10:58 AM, Ethan Dicks <a class="moz-txt-link-rfc2396E" href="mailto:ethan.dicks@gmail.com"><ethan.dicks@gmail.com></a> wrote:
On Wed, Jan 20, 2016 at 8:37 PM, Johnny Billquist <a class="moz-txt-link-rfc2396E" href="mailto:bqt@softjar.se"><bqt@softjar.se></a> wrote:
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<pre wrap="">ODT actually stands for On-line Debugging Tool, not Online Debugging
Technique.
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I recall Octal Debugging Technique. Anyone else remember that definition?
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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
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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.)<br>
<br>
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 <b>only</b>
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. <br>
<br>
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.)<br>
<br>
An early DDT manual (~ 1970, but I've lost the colophon page)
explains the DDT situation thusly:<br>
<br>
<div align="center">INTRODUCTION<br>
</div>
DDT-10 (for Dynamic Debugging Technique) * .... long page<br>
<br>
In very small print, smaller than I can reproduce here:<br>
<font size="-2">*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 (C<sub>14</sub>H<sub>9</sub>Cl<sub>5</sub>)
should be minimal since each attacks a different, and apparently
mutually exclusie, class of bugs.<br>
</font><br>
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.<br>
<br>
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 $B to set a
breakpoint. My fingers still rebel at verbose commands and
carriage-returns when debugging on 'modern' machinery.<br>
<br>
The other somewhat amusing thing is that DDT's adoption of the
<ESC> (echoed as '$') key required a lot of explanation in the
manuals, as various models of Teletype<sup>TM </sup>caused keys
located in the upper left corner of their keyboard to emit different
codes -- or the same codes, with different labels. The monitor had
SET TTY commands to map these down to <033>.<br>
<br>
And that's more than you wanted to know...probably.<br>
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