[TUHS] History of cal(1)?

[TUHS] History of cal(1)?

[Dan Cross via TUHS]

Over on the Multicians list, Jeffrey Johnson asked a question about
the Multics `calendar` program, which was written by Tom van Vleck in
Dec, 1973. Despite what some man pages say, the analogous Unix `cal`
program appears to have arrived in the 5th Edition (mid 1974).
Jeffrey's question was whether `cal` was inspired by `calendar`?

My suspicion is that it was not, and this is a case of parallel
invention: after all, a program that prints out a calendar is
obviously useful.  I also suspect that program, or something
substantially similar, had existed for quite a while before someone
tossed it into /usr/source/s1 in time for 5th Edition.  Does anyone
recall who wrote it, and when?

But this also rekindles my curiosity about something I've always
wondered: what _was_ the level of communication between the folks at
Bell Labs and the Multics people after 1969?  By all accounts,
individuals remained friendly and collegial with one another, but it
seems like communication (let alone collaboration) between the two
"camps" was minimal.  Is that accurate?

        - Dan C.

[TUHS] Re: History of cal(1)?

[Cameron Míċeál Tyre via TUHS]

Hi Dan,

This is not a full answer to your question but cal appeared in Research UNIX 1st Edition, Nov 3, 1971.

I'd be interested to compare the source code, in terms of how it was implemented, between the original and the version I have on this phone which is part of util-linux 2.40.2.

Best regards,

Cameron Tyre

[TUHS] Re: History of cal(1)?

[Dan Cross via TUHS]

On Thu, Sep 18, 2025 at 1:36 PM Cameron Míċeál Tyre via TUHS
<tuhs@tuhs.org> wrote:
> Hi Dan,
>
> This is not a full answer to your question but cal appeared in Research UNIX 1st Edition, Nov 3, 1971.

Ah, good catch!  It was in /usr/ken and in section 6 of the manual
(games), not section 1.

> I'd be interested to compare the source code, in terms of how it was implemented, between the original and the version I have on this phone which is part of util-linux 2.40.2.

Well, for starters, I'd guess it was in assembly language.

        - Dan C.

[TUHS] Re: History of cal(1)?

[Clem Cole via TUHS]

On Thu, Sep 18, 2025 at 12:54 PM Dan Cross via TUHS <tuhs@tuhs.org> wrote:

> ...
>
> But this also rekindles my curiosity about something I've always
> wondered: what _was_ the level of communication between the folks at
> Bell Labs and the Multics people after 1969?  By all accounts,
> individuals remained friendly and collegial with one another, but it
> seems like communication (let alone collaboration) between the two
> "camps" was minimal.  Is that accurate?
>
Doug and Ken are the best to answer for the MH folk.

But I'll take a stab at the communications within the CS Research Community
during the 70s, which I lived in.

As we all know, Unix spread quickly outside of MH to researchers, and a
great deal of development took place "on the outside."  Some of those ideas
came back to the Research versions, but not all.   But I think there was a
good bit of cross-pollination within the community — even before Usenet or
the Internet itself.   Sometimes we would swap magnetic tapes directly, and
often we would bring tapes to a conference with our work and come home
with work from others.  We knew each other and talked.

Taking MetCalfe's law into account, because there so many Unix
installations (and we were all talking to each other), that style of
sharing could not happen with Multics,  I will posit that by 1975 most, if
not nearly all, researchers in the systems world were at least familiar
with Elliott Organick's 1972 book — "*The Multics System: An Examination of
its Structure*," and many of us had read it and trying to learn lessons
from it.  It was a text that was referred to in my undergrad OS course, and
by the time I was a grad student working in systems, it was pretty much
assumed that everyone in the room had read it.

I certainly thought Multics had some cool ideas. However, I barely touched
a Multics system in those days via my limited remote access (MIT's system).
And I never physically saw a Multics-capable processor until many years
later. I admit that from reading Organski's book, I had some wild images of
computer operators mounting mag tapes so a program could continue execution
after a segment defined as not being directly addressable.  So while I was
familiar with Multics,  I certainly "knew" a lot more about UNIX.  I had
it, and I was hacking its kernel.   I personally did little of what we call
programming on Multics, and at the same time, I was being paid to program
in Unix (and some TOPS-10/TOPS-20 shop).

I don't think I'm really unique here.   If the data from website
Multicians.org is correct, there were just too few Multics installations to be
found (11 in 1975), and only two were at universities (MIT and the
University of Louisiana). The other nine were at commercial sites.  Note
that in 1975, we know there were at least 5 times the number of Unix
installations.  Most of these sites were ones that had had some level of CS
Research.  By 1979, the numbers were 25 for Multics and over 600 for Unix.

By 1979, Multics OS was stable, and the hardware to run it (the "3rd
generation" H6180 had been on the market since 1973) had certainly matured
from the original GE-645. So why did Multics not play a more significant
role? Once again, core economics of the time played a huge part. If you use
Google AI, it will tell you that a Honeywell H6180 computer system running
Multics, like MIT was running in 1979, had a list price of about $7 million
when it was introduced. This price included a complete system with multiple
components, not just the central computer unit.  Now think about a PDP
11/34, with full 256K bytes of memory, a couple of RK05 and probably an
RP04 equivalent as its disk, 9-track tape, Printonix printer, and 16 serial
ports using after-market DH11 — a pretty standard V7 installation, which
costs approximately $100-150K.  Even if you ran it on a Vax, it was not
more than approximately 3 times that number.  But this is a massive
difference from the $7M for a Multic system.

It's a simple Christenson disruption —  the "lesser" system wins over the
earlier, more "mature", and full-featured, "better" one.  As a result,
cross-pollination opportunities were not available.   Unix/V7 and its
derivatives got the attention of units because the economics favored it.
Just like Linux receives today.

Clem

[TUHS] Re: History of cal(1)?

[Dan Cross via TUHS]

On Thu, Sep 18, 2025 at 3:52 PM Clem Cole <clemc@ccc.com> wrote:
> [snip]
> But I'll take a stab at the communications within the CS Research Community during the 70s, which I lived in.

Thanks, Clem: this is just the sort of thing I am interested in.

I realize this is veering off toward COFF territory, but another
couple of follow-up questions; inline.

> As we all know, Unix spread quickly outside of MH to researchers, and a great deal of development took place "on the outside."  Some of those ideas came back to the Research versions, but not all.   But I think there was a good bit of cross-pollination within the community — even before Usenet or the Internet itself.   Sometimes we would swap magnetic tapes directly, and often we would bring tapes to a conference with our work and come home with work from others.  We knew each other and talked.

So I sort of wonder if the Multics folks also showed up to some of
those conferences: SOSP, for example. I imagine people like Fano and
Corby attended. And the Unix community coalesced quickly and became
quite strong (as we all know), I wonder about interaction with other
communities.

To be a tad pithy about it, did folks get together for coffee during
the hallway track? Grab dinner or a drink in the evening? That kind of
thing.

> Taking MetCalfe's law into account, because there so many Unix installations (and we were all talking to each other), that style of sharing could not happen with Multics,  I will posit that by 1975 most, if not nearly all, researchers in the systems world were at least familiar with Elliott Organick's 1972 book — "The Multics System: An Examination of its Structure," and many of us had read it and trying to learn lessons from it.  It was a text that was referred to in my undergrad OS course, and by the time I was a grad student working in systems, it was pretty much assumed that everyone in the room had read it.
>
> I certainly thought Multics had some cool ideas. However, I barely touched a Multics system in those days via my limited remote access (MIT's system). And I never physically saw a Multics-capable processor until many years later. I admit that from reading Organski's book, I had some wild images of computer operators mounting mag tapes so a program could continue execution after a segment defined as not being directly addressable.  So while I was familiar with Multics,  I certainly "knew" a lot more about UNIX.  I had it, and I was hacking its kernel.   I personally did little of what we call programming on Multics, and at the same time, I was being paid to program in Unix (and some TOPS-10/TOPS-20 shop).
>
> I don't think I'm really unique here.   If the data from website Multicians.org is correct, there were just too few Multics installations to be found (11 in 1975), and only two were at universities (MIT and the University of Louisiana). The other nine were at commercial sites.  Note that in 1975, we know there were at least 5 times the number of Unix installations.  Most of these sites were ones that had had some level of CS Research.  By 1979, the numbers were 25 for Multics and over 600 for Unix.
>
> By 1979, Multics OS was stable, and the hardware to run it (the "3rd generation" H6180 had been on the market since 1973) had certainly matured from the original GE-645. So why did Multics not play a more significant role? Once again, core economics of the time played a huge part. If you use Google AI, it will tell you that a Honeywell H6180 computer system running Multics, like MIT was running in 1979, had a list price of about $7 million when it was introduced. This price included a complete system with multiple components, not just the central computer unit.  Now think about a PDP 11/34, with full 256K bytes of memory, a couple of RK05 and probably an RP04 equivalent as its disk, 9-track tape, Printonix printer, and 16 serial ports using after-market DH11 — a pretty standard V7 installation, which costs approximately $100-150K.  Even if you ran it on a Vax, it was not more than approximately 3 times that number.  But this is a massive difference from the $7M for a Multic system.
>
> It's a simple Christenson disruption —  the "lesser" system wins over the earlier, more "mature", and full-featured, "better" one.  As a result, cross-pollination opportunities were not available.   Unix/V7 and its derivatives got the attention of units because the economics favored it.  Just like Linux receives today.

These are really great points. It sure seems like Multics has had a
huge influence, but indirectly, as it was difficult to come by for
actual use.

Thanks again, Clem.

        - Dan C.

[TUHS] SOSP 1973 [was Multics<->Unix Re: Re: History of cal(1)?

[Charles H Sauer (he/him) via TUHS]

[trying to broaden the discussion & transition to COFF]

On 9/19/2025 2:57 PM, Dan Cross via TUHS wrote:
> So I sort of wonder if the Multics folks also showed up to some of
> those conferences: SOSP, for example. I imagine people like Fano and
> Corby attended. And the Unix community coalesced quickly and became
> quite strong (as we all know), I wonder about interaction with other
> communities.

Looking at the SOSP 1973 list of presentations at 
https://dblp.org/db/conf/sosp/sosp73.html, where Dennis & Ken presented 
Unix at IBM Yorktown, there's only one presentation obviously Multics 
related, by Saltzer, and no other presentations obviously associated 
with currently well known operating systems.

In the (admittedly, insular) IBM environment, there seemed little 
interest in anything besides MVS for production and VM/370 for 
development. (From Popek/Goldberg SOSP 1973 Abstract: "Virtual machine 
systems have been implemented on a limited number of third generation 
computer systems, e.g. CP-67 on the IBM 360/67. From previous empirical 
studies, it is known that certain third generation computer systems, 
e.g. the DEC PDP-10, cannot support a virtual machine system.")

As late as 1979 at UT-Austin, Unix was not available in the C.S. Dept -- 
TOPS-10 was gaining traction over the homegrown "UT-2D" environment for 
CDC 6400/6600 and the subsequent CDC machines that supplanted those.

For various reasons, lack of commercial dominance, lack of source, ..., 
there didn't seem to be any specific OS that gained mind share in the 
O.S. community until Unix did. Well after 1985 in IBM, those of us 
advocating Unix were definitely in the minority. 
[https://notes.technologists.com/notes/2017/03/08/lets-start-at-the-very-beginning-801-romp-rtpc-aix-versions/]

Charlie

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[TUHS] Re: History of cal(1)?

[John Levine via TUHS]

It appears that Dan Cross via TUHS <crossd@gmail.com> said:
>My suspicion is that it was not, and this is a case of parallel
>invention: after all, a program that prints out a calendar is
>obviously useful. ...

It is, but a program that has all the logic to adjust for 16th century
calendar changes, not so much.  (Try "cal 9 1752")

My impression is that the Unix cal program was always this overimplemented
so perhaps we can see whether other earlier programs did that too.

R's,
John

[TUHS] Re: History of cal(1)?

[Dan Cross via TUHS]

On Sat, Sep 20, 2025 at 4:35 PM John Levine <johnl@taugh.com> wrote:
> It appears that Dan Cross via TUHS <crossd@gmail.com> said:
> >My suspicion is that it was not, and this is a case of parallel
> >invention: after all, a program that prints out a calendar is
> >obviously useful. ...
>
> It is, but a program that has all the logic to adjust for 16th century
> calendar changes, not so much.  (Try "cal 9 1752")

The amount of logic required to handle that in the 5th Ed version of
`cal` is surprisingly small, consisting of only three places and
perhaps a total of 8 or 9 lines of code, depending on how one wants to
count.

> My impression is that the Unix cal program was always this overimplemented
> so perhaps we can see whether other earlier programs did that too.

I edited a copy to get it to compile with a recent compiler. The
changes were mainly to modernize the C dialect `=+` vs `+=` and that
kind of thing; I added prototypes in a handful of places, and used ISO
function definitions and a couple of `#include`'s. The result is 214
lines of code, including whitespace.  Forgive me, but I'd hardly call
that "over-implemented."

THVV's Multics calendar program is actually meant to produce printable
calendars to hang on a wall, with enough space that one could write
birthdays and so forth onto them, as one might on a hanging calendar
bought in a store. That program is over a thousand lines of code PL/1
code (including significant comments and whitespace):
https://github.com/dancrossnyc/multics/blob/main/library_dir_dir/system_library_standard/source/bound_printing_cmds_.s.archive/calendar.pl1

Multics calendar does not appear to handle the Sep 1752 switch, however.

        - Dan C.

[TUHS] Re: History of cal(1)?

[Jeff Johnson via TUHS]

You can also look at the code with (what should be) better indentation and proper syntax highlighting at https://dps8m.gitlab.io/sb/MR12.8/library_dir_dir/system_library_standard/source/bound_printing_cmds_.s.archive/calendar.pl1.html

THVV’s also allows adding custom text and holidays before printing and it also includes code for calculating the date of Easter.

It’s a quite the featureful program for when it was introduced.

--
Jeffrey H. Johnson
trnsz@pobox.com

[TUHS] History of cal(1)?

[Douglas McIlroy via TUHS]

> [cal(1)] has all the logic to adjust for 16th century
> calendar changes ...  (Try "cal 9 1752")
> My impression is that [it is] overimplemented.

The fact that a 16th century change is illustrated by an 18th century
example suggests that not quite "all the logic" is there. It's good
for Great Britain and its colonies, but not elsewhere. So I'd say it's
underimplemented :)

Doug