18 Jul
2025
18 Jul
'25
7:42 p.m.
I see the Wikipedia "Flag day (computing)" [1] article references two
semi-different ESR sources [2,3] to support the claim:
This systems terminology originates from a major
change in the Multics
operating system's definition of ASCII, which was
scheduled for the United
States holiday, Flag Day, on June 14, 1966.
I don't doubt the validity, but I'm looking for other "citation
worthy"
sources that supplement this claim --- ideally that predate the ESR ones,
so that they are unambiguously independent.
1. https://en.wikipedia.org/wiki/Flag_day_(computing)
2. http://www.catb.org/jargon/html/F/flag-day.html
3. *The New Hacker's Dictionary*
<https://books.google.com/books?id=g80P_4v4QbIC&pg=PA192>pp. 192–
--
Royce Williams
Tech Solvency
18 Jul
18 Jul
8:08 p.m.
Interestingly, that phrasing comes directly from morticians.org. Or rather,
instead of implying something, I should say that the wording between the
two is exactly the same
You could ask over on that site, I think there's some kind of mailing list,
if there's more info available.
10:50 p.m.
On Fri, Jul 18, 2025 at 5:02 PM Rich Salz <rich.salz(a)gmail.com> wrote:
Interestingly, that phrasing comes directly from
morticians.org.
People are dying to find out what's on that site....
(Ok, sorry; clearly Rich typo'ed "multicians.org" here, but I couldn't
resist.)
Or rather, instead of implying something, I should say
that the wording between the two is exactly the same
You could ask over on that site, I think there's some kind of mailing list, if
there's more info available.
There is. The multicians mailing list is very informative and
friendly, but much lower traffic than TUHS.
- Dan C.
10:55 p.m.
On Fri, Jul 18, 2025 at 4:50 PM Dan Cross <crossd(a)gmail.com> wrote:
On Fri, Jul 18, 2025 at 5:02 PM Rich Salz <rich.salz(a)gmail.com> wrote:
I thought it was a purposeful choice to go from multicians to
morticians after Multics had been retired for long enough :) With
technical people, you never know...
Warner
Interestingly, that phrasing comes directly from
morticians.org.
People are dying to find out what's on that site....
(Ok, sorry; clearly Rich typo'ed "multicians.org" here, but I
couldn't resist.) 
19 Jul
19 Jul
2:44 a.m.
There are still a few Multics sites running - and semi-active community
development.
Courtesy of an old fork of SIMH that became a very full fledged DPS8/6800
simulator. I was running MR11 something on a Pi for a while, and then in
GCP.
Brought back old times - my second computer - after GCOS.
*sigh*
I think there may also be a reference to Flag Day in the original printed
Hacker's Dictionary, and I think in the Jargon file from which it was
derived? I don't have any old copies of either around to check
--tep
On Fri, Jul 18, 2025 at 4:02 PM Warner Losh <imp(a)bsdimp.com> wrote:
On Fri, Jul 18, 2025 at 4:50 PM Dan Cross
<crossd(a)gmail.com> wrote:
On Fri, Jul 18, 2025 at 5:02 PM Rich Salz <rich.salz(a)gmail.com> wrote:
resist.)
I thought it was a purposeful choice to go from multicians to
morticians after Multics had been retired for long enough :) With
technical people, you never know...
Warner
Interestingly, that phrasing comes directly from
morticians.org.
People are dying to find out what's on that site....
(Ok, sorry; clearly Rich typo'ed "multicians.org" here, but I
couldn't 
3:02 a.m.
On 19 Jul 2025, at 12:44, Tom Perrine
<tom.perrine+tuhs(a)gmail.com> wrote:
<…>
I think there may also be a reference to Flag Day in
the original printed Hacker's Dictionary, and I think in the Jargon file from which
it was derived? I don't have any old copies of either around to check
It’s in the “New Hackers Dicrionary” from 1991:
https://www.dropbox.com/scl/fi/rwgb1ajk4n3sfkb2ejbd6/Photo-19-7-2025-12-54-…
https://www.dropbox.com/scl/fi/v1h4myystwj0pirgcaa1z/Photo-19-7-2025-12-55-…
https://www.dropbox.com/scl/fi/jp4tlisj2j33ldzdt4n99/Photo-19-7-2025-12-56-…
d
3:11 a.m.
On Fri, Jul 18, 2025, 9:02 PM David Arnold <davida(a)pobox.com> wrote:
On 19 Jul 2025, at 12:44, Tom Perrine
<tom.perrine+tuhs(a)gmail.com> wrote:
<…
I think there may also be a reference to Flag Day in the original printed
Hacker's Dictionary, and I think in the Jargon file from which it was
derived? I don't have any old copies of either around to check
It’s in the “New Hackers Dicrionary” from 1991:
https://www.dropbox.com/scl/fi/rwgb1ajk4n3sfkb2ejbd6/Photo-19-7-2025-12-54-…
https://www.dropbox.com/scl/fi/v1h4myystwj0pirgcaa1z/Photo-19-7-2025-12-55-…
https://www.dropbox.com/scl/fi/jp4tlisj2j33ldzdt4n99/Photo-19-7-2025-12-56-…
RFC 801 documents the NCP to TCP flag day of Jan 1, 1982. But doesn’t use
that term despite latter day documents using that term.
Warner
3:06 a.m.
Don't want to stray too off-topic but ...
DPS8M development is quite active, see https://dps8m.gitlab.io/ - a new point
release is coming soon, and other projects are in active development, like
an FPGA implementation of the DN6678 (and eventually the DPS8/M CPU). A lot
of the work is going into developer tooling for those projects, which isn't
that interesting to the "general public", but the community is very busy.
The guys working on it just spend more time hacking that posting updates
about the work! (but we do have a blog at https://dps8m.gitlab.io/blog/)
Since you mentioned GCOS, you should know that a lot of effort was recently
spent to get the GCOS environment up and working. Note this is GCOS being
emulated in Multics, not GCOS on the metal (yet - we need tapes). A better
write-up is actually in progress, but for now you can check the Wiki page:
https://multics-wiki.swenson.org/index.php/GCOS
(And yes, the simulator was originally a fork of SIMH to start, but at
this point it's barely related and future versions will have even less
SIMH code. This isn't to knock that project at all, just that DPS8M
simulator development has moved in a different direction.)
As the Flag Day, the only reference that I know to it is the one on the
multicians.org website. I could ask on the multicians list, or send an
inquiry to Tom Van Vleck.
--
Jeffrey H. Johnson
trnsz(a)pobox.com
On Fri, Jul 18, 2025, at 10:44 PM, Tom Perrine wrote:
There are still a few Multics sites running - and
semi-active community development.
Courtesy of an old fork of SIMH that became a very full fledged DPS8/6800 simulator. I
was running MR11 something on a Pi for a while, and then in GCP.
Brought back old times - my second computer - after GCOS.
*sigh*
I think there may also be a reference to Flag Day in the original printed Hacker's
Dictionary, and I think in the Jargon file from which it was derived? I don't have
any old copies of either around to check
--tep
3:34 p.m.
Royce Williams <royce(a)techsolvency.com> writes:
I don't doubt the validity, but I'm looking
for other "citation
worthy" sources that supplement this claim --- ideally that predate
the ESR ones, so that they are unambiguously independent.
You can see the early history of the Jargon File through the SAIL copy,
which is AIWORD.RF in this directory:
https://www.saildart.org/[UP,DOC]/
The FLAG DAY entry was added between 1977-02-01 and 1977-03-11, and
initially read:
| FLAG DAY [from a bit of Multics history involving a change in the
| ASCII character set originally scheduled for June 14, 1966]
| n. A software change which is neither forward nor backward
| compatible, and which is costly to make and costly to revert.
| "Can we install that without causing a flag day for all users?"
That appears to be the earliest instance of the term in the public
SAILDART files. The next I could see is in a mail message from Mark
Crispin on 1977-10-01. (He must have liked the term; in the utzoo Usenet
archive, quite a lot of the early examples are from him too!)
--
Adam Sampson <ats(a)offog.org> <http://offog.org/>
3:46 p.m.
On Sat, Jul 19, 2025 at 11:34 AM Adam Sampson <ats(a)offog.org> wrote:
The FLAG DAY entry was added between 1977-02-01 and 1977-03-11
This matches my memory. BTW: 1975 it was in day-to-day lingo in the
ARPANET community, such as I was in at CMU, so I suspect it was from much
earlier, such as the Multics reference. At some point - which looks like
early 1977, someone added it to the Jargon file, but it was hardly a
new term by then.
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Adam Sampson -
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Dan Cross -
David Arnold -
Jeff Johnson -
Rich Salz -
Royce Williams -
Tom Perrine -
Warner Losh