TUHS October 2024

tuhs@tuhs.org

45 participants
24 discussions

by Paul Ruizendaal

In the last months, I've spent a little time on curating John Walker's Unix clone and software stack, including an emulator to run it: https://gitlab.com/marinchip After creating a basic tool chain (edit, asm, link and a simple executive), John set out to find a compiler. Among the first programs were a port of the META 3 compiler-generator (similar to TMG on early Unix) and a port of Birch-Hansen’s Pascal compiler. META was used to create a compiler that generated threaded code. He found neither compiler good enough for his goals and settled on writing his Unix-like OS in assembler. As the 9900 architecture withered after 1980, this sealed the fate of this OS early on -- had he found a good compiler, the code might have competed alongside Coherent, Idris, and Minix during the 80’s. This made me realise once more how unique the Ritchie C compiler was. In my view its uniqueness combines three aspects: 1. The C language itself 2. The ability to run natively on small hardware (even an LSI-11 system) 3. Generating code with modest overhead versus handwritten assembler (say 30%) As has been observed before, working at a higher abstraction level makes it easier to work on algorithms and on refactoring, often earning back the efficiency loss. John Walkers work may be case in point: I estimate that his hand-coded kernel is 10% larger than an equivalent V6 Unix kernel (as compiled for the 9900 architecture). There are three papers on DMR’s website about the history of the compiler and a compare-and-contrast with other compilers of the era: https://www.bell-labs.com/usr/dmr/www/primevalC.html https://www.bell-labs.com/usr/dmr/www/chist.html https://www.bell-labs.com/usr/dmr/www/hopl.html It seems to me that these papers rather understate the importance of generating good quality code. As far as I can tell, BCPL and BLISS came close, but were too large to run on a PDP-11 and only existed as cross-compilers. PL/M was a cross-compiler and generated poorer code. Pascal on small machines compiled to a virtual machine. As far as I can tell, during most of the 70s there was no other compiler that generated good quality code and ran natively on a small (i.e. PDP-11 class) machine. As far as I can tell the uniqueness was mostly in the “c1” phase of the compiler. The front-end code of the “c0” phase seems to use more or less similar techniques as many contemporary compilers. The “c1” phase seems to have been unique in that it managed to do register allocation and instruction selection with a pattern matcher and associated code tables squeezed into a small address space. On a small machine, other native compilers of the era typically proceeded to generate threaded code, code for a virtual machine or poor quality native code that evaluated expressions using stack operations rather than registers. I am not sure why DMR's approach was not more widely used in the 1970’s. The algorithms he used do not seem to be new and appear to have their roots in other (larger) compilers of the 1960’s. The basic design seems to have been in place from the very first iterations of his compiler in 1972 (see V2 tree on TUHS) and he does not mention these algorithms as being special or innovative in his later papers. Any observations / opinions on why DMR’s approach was not more widely used in the 1970’s?

2 months, 3 weeks

Re: v6 Unix Documents

by Jonathan Gray

On Sun, Oct 20, 2024 at 01:23:23AM -0400, Dan Plassche wrote: > > On Sat, 19 Oct 2024, Jonathan Gray wrote: > > > PWB was an early external distribution with troff. > > > > Documents for the PWB/UNIX Time-Sharing System > > https://datamuseum.dk/wiki/Bits:30007124 > > https://bitsavers.org/pdf/att/unix/PWB_UNIX/ > > > > NROFF/TROFF User's Manual > > October 11, 1976 > > datamuseum.dk, pp 325-357 > > bitsavers, pp 217-249 > > > > Addendum to the NROFF/TROFF User's Manual > > May 1977 > > datamuseum.dk, p 358 > > bitsavers, p 250 > > > > fonts described in: > > Administrative Advice for PWB/UNIX > > 23. PHOTOTYPESETTING EQUIPMENT AND SUPPLIES > > datamuseum.dk, p 647 > > Thank you Jonathan. I was previously not sure where to place the > PWB documentation in the timeline but a clearer picture is > emerging. > > Based on the v6 "NROFF User's Manual" revised in 1974 and > published in 1975, I can now see that the PWB documentation with > the "NROFF/TROFF User's Manual" from 1976-77 has most of the > content that later appears in v7. The major change immediately > beforehand was the rewrite of troff into C.[1] Some clear > differences are the combination of nroff and troff manpages and > the addition of troff specific features like the special fonts > into the user's manual. > > [1]. Apparently in 1976: > https://www.tuhs.org/Archive/Distributions/USDL/unix_program_description-tr… "It was rewritten in C around 1975" Kernighan in CSTR 97, A Typesetter-independent TROFF I've seen references to "Documents for Use with the Phototypesetter (Version 7)" which was likely distributed with the licensed phototypesetter tape in 1977. What may have been the manual distributed with that tape is also close to v7. https://www.tuhs.org/cgi-bin/utree.pl?file=Interdata732/usr/source/troff/doc https://www.tuhs.org/Archive/Distributions/Other/Interdata/ tuhs Applications/Spencer_Tapes/unsw3.tar.gz usr/source/formatters/troff/doc/

3 months, 3 weeks

Re: Minimum Array Sizes in 16 bit C (was Maximum)

by Douglas McIlroy

>>> malloc(0) isn't undefined behaviour but implementation defined. >> >> In modern C there is no difference between those two concepts. > Can you explain more about your view There certainly is a difference, but in this case the practical implications are the same: avoid malloc(0). malloc(0) lies at the high end of a range of severity of concerns about implementation-definedness. At the low end are things like the size of ints, which only affects applications that may confront very large numbers. In the middle is the default signedness of chars, which generally may be mitigated by explicit type declarations. For the size of ints, C offers guardrails like INT_MAX. There is no test to discern what an error return from malloc(0) means. Is there any other C construct that implementation-definedness renders useless? Doug

4 months

QED Archive updated

by arnold＠skeeve.com

Hi All. For anyone who's interested, my QED archive at https://github.com/arnoldrobbins/qed-archive has been updated. Changes were provided by Sean Jensen. The usenix-80-caltech subdirectory is now more complete and the README.md points at Sean's updated QED port which now works with Unicode. I thank him. Arnold

4 months, 4 weeks

Other UNIX Archival Efforts?

by segaloco

So with all that has happened with the Internet Archive lately, I do find myself a bit concerned regarding the UNIX materials that I know to only exist there. Selfishly, this includes my own uploads here: https://archive.org/details/@segaloco I was curious if anyone has any suggestions on places beyond just IA and TUHS where I could see about getting this stuff mirrored? Unfortunately my stuff runs afoul of bitsavers's DPI requirements, that's the only other source that immediately comes to mind where these materials would find home. Any thoughts? Warren, I know you had mentioned a "write only" archive you maintain regarding materials that need to be mothballed until legal understandings are reached, would you be comfortable with my contributing any of my materials the Caldera license does not apply to there? - Matt G.

5 months

v6 Unix Documents

by Dan Plassche

Hi, A scan of the printed UNIX Version 6 documents set is now online at the link below since last week. The set consists of documents accompanying the manual pages in the programmer's manual (similar to volume 2 in v7). https://www.computerhistory.org/collections/catalog/102659317 The [nt]roff user manual, tmg compiler-compiler, and m6 macro processor memos were previously missing from the distributions in TUHS and later efforts to re-create the documentation. I have been working on finding this documentation as part of researching roff history. Still interested in earlier copies of the internal memoranda from Ossanna that served as the NROFF User's Manual since v3, the TROFF User's Manual after v5, and TROFF Made Trivial starting around v4. Based on the manpage histories, the documentation was revised for v4, 5, and 6. Best, Dan Plassche

5 months

Re: On computerese

by Douglas McIlroy

> Who created the "cat" command and did they have the > word "catenate" or "concatenate" in their heads? Ken Thompson wrote "cat" for the PDP-7, with "concatenate" in mind. The cat(1) page in the v1 manual is titled, "concatenate (or print) files". Only later did someone in Research--I don't know who--remark on the existence of the shorter synonym. It was deliberately adopted in v7, perhaps because it better mirrored the command name. But brevity is the defensible argument for "catenate", while familiarity boosts "concatenate". It stll takes some conscious effort for me to use the former, However, I sense sinister vibes in "concatenate", driven by the phrase "concatenation of events", which often is used to explain misfortune. Doug

5 months

Re: lilian schwartz has died

by Rob Pike

I always forget that TUHS can't handle pictures. Perhaps Warren will let my post through, but in any case here's a link to the mail, reformatted but otherwise intact, with photos, on Mastodon. https://hachyderm.io/@robpike/113322062117546253 To pique your interest, here's the first paragraph. *In August 1981 we had a persistent problem with the RP06 on our PDP-11/70 crashing disks. It even crashed once while the DEC repairman was standing next to it trying to figure out why the previous pack had died. We collected a few dead packs, and they were forming a pile. Lillian, never one to miss an opportunity, suggested building a mobile.* -rob

5 months, 1 week

Can Ancient Unix be relicensed?

by Anton Shepelev

Hello, all. In 2002, Caldera released Ancient Unix code under Caldera license: <https://www.tuhs.org/Archive/Caldera-license.pdf> based on the four-clause BSD license: <https://spdx.org/licenses/BSD-4-Clause.html> Consequently, it was used by derived projects, such as Traditional Vi: <https://ex-vi.sourceforge.net/> This proect having been abandoned and orphaned since 2005, I wanted to host it on GNU Savanna and there to breath some life into it. Unfortunately, the 4-clause BSD license is incompatible with GPL: <https://www.gnu.org/licenses/license-list.html#OriginalBSD> The incompatibilty is due entirely to the infamous third clause about adverising. Three years prior to Caldera's release of old Unix code, The Berkley Univercity removed this clause, producing the GNU-compatible modified BSD License: <https://opensource.org/license/BSD-3-clause> They published a notice to that effect on their FTP: <ftp://ftp.cs.berkeley.edu/pub/4bsd/README.Impt.License.Change> Although it has been taken down[1], copies exist all over the internet, e.g.: <https://raw.githubusercontent.com/abbrev/punix/refs/heads/master/README.Imp…> That said, is there a chance that the copyright holder of Ancient Will agree to release a similar note regarding everying released under Caldera license? If there is, whom shall I contact about it? It will benefit everybody using Ancient Unix code. ____________________ 1. Why the murrain of FTP servers all over the world?

5 months, 1 week

Draft v5: London and Reiser's UNIX VAX port paper, reconstructed

by G. Branden Robinson

Hi folks, A few months ago I reported on my efforts to reconstruct London & Reiser's paper on their port of Unix to the VAX-11/780.[1] I formerly characterized this as "the UNIX/32V port", but since London & Reiser's paper predates the release of Seventh Edition Unix by about six months, UNIX/32V came _after_ Seventh Edition by about the same number of months, and the pace of Unix development was particularly ferocious in this period[2], I felt that my identification of London & Reiser's work with UNIX/32V may have been hasty. I also may have overinterpreted Dennis Ritchie's words on the subject. "Tom London and John Reiser, working from the 7th Edition and the Interdata 8/32 system, generated a VAX 11/780 version of the system, which, in its distribution format, would be called 32V." That phrase "in its distribution format" could cover a variety of changes, some of which perhaps did not match London & Reiser's intentions or views expressed in their paper. More conservative implications seemed prudent. I'd thus like to present what I consider to be my "final" draft, subject of course to feedback from these mailing lists. I'm pleased to report that I've addressed all of the XXX points I identified in the source of my first draft, points where I felt groff mm could be enhanced to aid the rendering of historical documents like this. I consequently expect groff 1.24's mm package to support several new features prompted specifically by this work. Quoting the forthcoming NEWS file... * The m (mm) macro package now supports a user-definable hook macro `AFX`, which if defined is called by `AF` in lieu of the latter's normal operation. Applications include customization of letterhead. * The m (mm) macro package now supports a user-definable hook macro `RPX`, which if defined is called by `RP` to format the reference list caption string `Rp` instead of the default formatting. * The m (mm) macro package now supports an `Aumt` string to suppress the appearance of positional arguments to the `AU` macro in the document heading used by memorandum types 0-3 and 6. By default, all such arguments appear, except the second (author initials). For example, a value of "3 4" more accurately reproduces London & Reiser's 1978 paper describing the porting of Unix to the VAX-11/780. * The m (mm) macro package now supports an `Rpfmt` string specifying the `LB` macro arguments that the package uses to format the items in a reference list. * The m (mm) macro package no longer superscripts _and_ brackets a reference mark (the `Rf` string). Instead, the new `Rfstyle` register controls its formatting. The default, 0, selects bracketing in nroff mode and superscripting in troff mode. Set `Rfstyle` to 3 in a document to obtain groff mm's previous mark formatting behavior. [I might still update or revert the changed default; I want to research the behavior of historical mm implementations.] The "32vscan.pdf" document from which I prepared this reconstruction is available at Dennis Ritchie's memorial home page.[3] I have attached the reconstructed mm source document and two PDFs, rendered with groff 1.23.0 (the current stable release), and groff Git HEAD (exercising the new features listed above).[4] I offer the caveat that these cannot be pixel-perfect recreations because (1) I have no information about the precise paper dimensions or margins London & Reiser used[5]; (2) the fonts employed in rendering the documents are not identical, metrically or otherwise; and (3) AT&T and GNU troffs use different hyphenation systems and therefore sometimes break words differently. These factors all impact the placement of line and page breaks, and these are avowedly and clearly distinguishable. There are furthermore a few discrepancies that I decided weren't worth the trouble at this time to reconcile, like selective encroachment of cover sheet material beyond the page margins. None affect the utility of the document (in my opinion). With that large disclaimer in place, I welcome feedback on the quality of the reproduction. Finally, I reiterate my encouragement that the document be _read_. In my opinion, the final two sections "Commands" and "Software portability" are well worth consideration in hindsight. To the extent that we continue to boast, sometimes glibly, of C as a "portable assembly language", be it in its current ISO C23 incarnation; as ANSI C89, the last revision blessed by Ritchie; or in the form used when London and Reiser wrote, their experiences and recommendations laid out a program of better delivering on that promise. Regards, Branden [1] https://www.tuhs.org/pipermail/tuhs/2024-June/030041.html [2] 1980, for example, saw releases of 3BSD, System III, PWB/UNIX 2.0, and 4BSD. [3] https://www.bell-labs.com/usr/dmr/www/portpapers.html [4] You may notice a difference in the sizes of the two PDFs, surprising in light of their shared source document. This is thanks to a new feature forthcoming in Deri James's gropdf(1) output driver: font subsetting. [5] ...or where, if anywhere, the authors "cheated" the margins temporarily, for instance with `ll` or `pl` requests. Even with mm macro package sources available, such things would be invisible to the reconstructor.

5 months, 1 week

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TUHS October 2024