> On Jan 21, 2016, at 2:27 PM, Timothe Litt <l...@ieee.org> wrote:
>
>> ...
> 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.
Neat. "Mutually exclusive"? I suppose in those days; earlier, not
necessarily, consider the famous story about the first bug as reported by Cmdr.
Grace Hopper.
I remember PASDDT. And yes, various PDP11 ODT flavors existed; the original
had rather primitive command parsing, which is why there were odd things like
;B to remove all breakpoints. As I recall, the original DOS ODT worked that
way, and perhaps the early (V2 era) RT11 ODT as well. Later versions with
slightly more available memory were friendlier, which is when removing
breakpoints became simply B without the odd semicolon.
> ...
> 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 TeletypeTM 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>.
Oh yes. ALT MODE and ... what was the third possible label? SEL?
While we're on the subject of oddball disclaimers: the RSTS monitor (kernel)
debugger was originally a hidden feature, in V4A. A couple of releases later
it became slightly less hidden. There was a manual for that debugger, which
described some of the additional things it could do (like direct examination of
data on RK05 disk). The manual title page came with what looked like a
standard DEC copyright / license disclaimer of that era, until you read it
carefully:
The material included in this document, limited to but not including,
construction speeds and operating purposes is for instruction times
only. All such claim is material without notice, and is bound to
change the subject.
The standard text of those days (as seen in published RSTS V4 manuals) looks
like this:
This document is for informational purposes and is subject to change
without notice. DEC assumes no responsibility for the use or
reliability of its software on equipment which is not supplied by DEC.
paul
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