TUHS June 2022

tuhs@tuhs.org

69 participants
32 discussions

Re: Sockets vs Streams (was Re: forgotten versions

by norman＠oclsc.org

As one of the few remaining people who has actually worked with the original dmr stream I/O system, I'd love to dive into the debate here, but I don't have time. I can't resist commenting on a few things that have flown by, though. Maybe I can find time to engage better on the weekend. -- If you think there were no record delimiters in the stream system, you don't know enough about it. A good resource to repair that is Dennis's BSTJ paper: https://www.bell-labs.com/usr/dmr/www/st.pdf It's an early description and some of the details later evolved (for example we realized that once pipes were streams, we no longer needed pseudoterminals) but the fundamentals remained constant. See the section about Message blocks, and the distinction between data and control blocks. Delimiters were one kind of control; there were others, some of them potentially specific to the network at hand. In particular, Datakit (despite being a virtual-circuit network) had several sorts of control words, including message delimiters. Delimiters were necessary even just for terminals, though: how else does the generic read(2) code know to return early, before filling the buffer, when a complete line has arrived? -- It's hard to compare sockets to streams and make much sense, because they are very different kinds of thing. When people talk about sockets, especially when complaining that sockets are a mess, they usually mean the API: system calls like connect and listen and getpeername and so on. The stream system was mainly about the internal structure-- the composable modules and the general-purpose queue interface between them, so that you could take a stream representing an (already set up) network connection and push the tty module on it and have a working remote terminal, no need for user-mode programs and pseudo-terminals. It's not inconceivable to build a system with socket-like API and stream internals. -- Connection setup was initially done with network-specific magic messages and magic ioctls. Later we moved the knowledge of that messy crap into network-specific daemons, so a user program could make a network call just by calling fd = ipcopen("string-destination-name") without knowing or caring whether the network transport was TCP or Datakit or involved forwarding over Datakit to a gateway that then placed a TCP call to the Internet or whatnot. That's what the connection server was all about: https://www.bell-labs.com/usr/dmr/www/spe.pdf Again, the API is not specific to the stream system. It wouldn't be hard to write a connection server that provided the same universal just-use-a-string interface (with the privileged parts or network details left up to daemons) on a system with only socket networking; the only subtle bit is that it needs to be possible to pass an open file descriptor from one process to another (on the same system), which I don't think the socket world had early on but I believe they added long ago. -- There's nothing especially hard about UDP or broadcast. It's not as if the socket abstraction has some sort of magic datagram-specific file descriptor. Since every message sent and every message received has to include the far end's address info, you have to decide how to do that, whether by specifying a format for the data (the first N bytes are always the remote's address, for example) or provide an out-of-band mechanism (some ioctl mess that lets you supply it separately, a la sendto/recvfrom, and encodes it as a control message). There was an attempt to make UDP work in the 9th/10th edition era. I don't think it ever worked very cleanly. When I took an unofficial snapshot and started running the system at home in the mid-1990s, I ended up just tossing UDP out, because I didn't urgently need it (at the time TCP was good enough for DNS, and I had to write my own DNS resolver anyway). I figured I'd get around to fixing it later but never did. But I think the only hard part is in deciding on an interface. -- It's certainly true that the Research-system TCP/IP code was never really production-quality (and I say that even though I used it for my home firewall/gateway for 15 years). TCP/IP wasn't taken as seriously as it ought to have been by most of us in 1127 in the 1980s. But that wasn't because of the stream structure--the IP implementation was in fact a copy of that from 4.2 (I think) BSD, repackaged and shoehorned into the stream world by Robert T Morris, and later cleaned up quite a bit by Paul Glick. Maybe it would have worked better had it been done from scratch by someone who cared a lot about it, as the TCP/IP implementors in the BSD world very much did. Certainly it's a non-trivial design problem--the IP protocols and their sloppy observance of layering (cf the `pseudo header' in the TCP and UDP standards) make them more complicated to implement in a general-purpose framework. Or maybe it just can't be done, but I wish someone had tried in the original simpler setup rather than the cluttered SVr4 STREAMS. Norman Wilson Toronto ON

2 years, 1 month

sockets [was Re: forgotten versions]

by Paul Ruizendaal

> Sockets (which btw, totally SUCK PUS) were coded into things > and even (YECHH) made POSIX and IETF spec status. Streams didn't stand > a chance. The question that originally pulled me into researching Unix networking 1975-1985 was more or less “how did we end up with sockets?”. That was 7 years or so ago, I now have a basic feel for how it came to be, and I also have better appreciation of the trade offs. What is the most “Unixy” of networking (as in the API and its semantics) is not something with an easy answer. If I limit myself to the 1975-1985 time frame, I see three approaches: 1. The API used in Arpanet Unix, which was also used by BBN in its first reference implementation of TCP/IP 2. The BSD sockets API, in two flavours: the Joy flavour in BSD4.1a, and the Karels flavour in BSD4.1c and later 3. The Ritchie/Presotto IPC library / API from V8/V9. This evolved into SysV networking, but the original is the clean idea At a high level of abstraction, there is a lot of similarity; close-up they are quite different. I like all three solutions! One thing that struck my attention was that the Ritchie/Presotto IPC library has the concept of “calling” a host and the host/network can reply with a response code (“line busy”, “number unknown”, “not authorised”, etc.). BSD sockets do not cover that. I guess it derives from Spider/Datakit having that functionality, and Arpanet / tcp-ip not having that (resorting to a connection ‘reset’ or dead line instead). Sockets have a more elegant solution for connectionless datagrams (imo), and for the same reason I guess. Sure, sockets has too much of the implementation sticking through the abstractions, but it is IMO not a bad design. That it became dominant I think is in equal measure due to economics and due to being “good enough”. If someone has a proposal for a network API that is cleaner and better than what was out there, and would have worked with the hardware and use cases of the early 80’s, I’m all ears. But maybe better on COFF... Paul

2 years, 1 month

Re: forgotten versions

by Paul Ruizendaal

Wholeheartedly agree with the observations on forgotten versions, lack of source and a smaller pool of people back in the day. It is not just the Research versions, also the internal AT&T versions and the base System V versions get little attention. Same reasons I think. Luckily, these days the sources are available (although in the case of SysV of unclear legal status). Part of the problem I think is that it is not well known what innovations are in each version. About 2 years ago I did a lot of spelunking through the V8 source and with the help of this list could come up with a list of highlights for V8 (text is now on the TUHS V8 source web page). Never had the time to do that for V9. I think it was mentioned that it had a new filesystem with a bitmap free list. Also, it seems to have a lot of cleaned-up implementations of things that were new and rough in V8. No clue what was new in V10. Similar with Unix 3, Unix 4 and Unix 5. I’m thrilled that the docs for Unix 4 showed up recently. In these doc’s there is no material on IPC. From this I think that the IPC primitives from CB-Unix did not get merged in Unix 4, but only in Unix 5 (in a reworked form). Personally, I’m still working (off and on) on recreating the Reiser demand paging system. To keep it interesting I’ve now got Sys III running on a small RISC-V board, and when I find another time slot I’ll try to add Reiser paging to it. So the forgotten versions are only mostly forgotten, not totally forgotten :^)

2 years, 1 month

Re: Documentation for Unix 4.0

by Norman Wilson

Maybe make www.tuhs.org a CNAME for tuhs.org? Surely a site devoted to the history of UNIX should use a real link, not a symbolic one. Norman `Old Fart' Wilson Toronto ON

2 years, 1 month

Re: Source code for SCCS

by Paul Ruizendaal

It would seem that a Spinellis-like exercise for SCCS is possible: PWB1.0 (1978): https://www.tuhs.org/cgi-bin/utree.pl?file=PWB1/sys/source/sccs4 SysIII (1980): https://www.tuhs.org/cgi-bin/utree.pl?file=SysIII/usr/src/cmd/sccs SysVr1 (1983): https://www.tuhs.org/cgi-bin/utree.pl?file=pdp11v/usr/src/cmd/sccs SysVr2 (1984): https://github.com/ryanwoodsmall/oldsysv/tree/master/sysvr2-vax/src/cmd/sccs SysVr3 (1987): https://github.com/ryanwoodsmall/oldsysv/tree/master/sysvr3/301/usr/src/cmd… SysVr4 (1988): https://github.com/ryanwoodsmall/oldsysv/tree/master/sysvr4/svr4/cmd/sccs Ultrix3.1 (1988): https://www.tuhs.org/cgi-bin/utree.pl?file=Ultrix-3.1/src/cmd/sccs I did not find SCCS sources included with the BSD sources on TUHS, but there is a front-end “sccs” command. For sure, SCCS was used for BSD development. Kirk McKusick’s DVD has a directory "CSRG/historic1/sccscmds”, but I did not look into this further. From here the trail probably continues with Solaris, GNU and Bitmover -- all very much outside my timeframe of research. Paul > The original Marc Rochchild/John Mashey and team code from PWB 1.0 can be > found: http://tuhs.org/Archive/Distributions/USDL/spencer_pwb.tar.gz > In the directory: sys/source/sccs4 > The man pages are in the same archive but mixed with the rest of the > commands in usr/man/man* > > That said, there is Gnu version of same written C++ if IIRC: > https://www.gnu.org/software/cssc/ > > And there's more ... but I'll Larry offer details here other than point out > his: http://www.bitmover.com/bitsccs/ [which is of BitKeeper] is a > more modern implementation still]

2 years, 1 month

Documentation for Unix 4.0

by Warren Toomey

Hi all, we have a new addition to the Unix Archive at: https://www.tuhs.org/Archive/Documentation/Manuals/Unix_4.0/ This is the documentation for Unix 4.0 which preceded System V. The documents were provided by Arnold Robbins and scanned in by Matt Gilmore. Cheers, Warren

2 years, 1 month

blast from the past

by Andrew Hume

this is an old video, new to me, but i’m sure others on this list have seen it. its a little long, but has al aho, jon bentley, bjarne, ken&denis, plan 9 amongst others. https://www.youtube.com/watch?v=IFfdnFOiXUU&t=2s <https://www.youtube.com/watch?v=IFfdnFOiXUU&t=2s>

2 years, 1 month

Fwd: [simh] Announcing the Open SIMH project

by Clem Cole

Announcing the Open SIMH project SIMH is a framework and family of computer simulators, initiated by Bob Supnik and continued with contributions (large and small) from many others, with the primary goal of enabling the preservation of knowledge contained in, and providing the ability to execute/experience, old/historic software via simulation of the hardware on which it ran. This goal has been successfully achieved and has for these years created a diverse community of users and developers. This has mapped to some core operational principles: First, preserve the ability to run old/historically significant software. This means functionally accurate, sometimes bug-compatible, but not cycle-accurate, simulation. Second, make it reasonably easy to add new simulators for other hardware while leveraging common functions between the simulators. Third, exploit the software nature of simulation and make SIMH convenient for debugging a simulated system, by adding non-historical features to the environment. Fourth, make it convenient for users to explore old system environments, with as close to historical interfaces, by mapping them to new features that modern host operating systems provide. Fifth, be inclusive of people and new technology. It's serious work, but it should be fun. Previously, we unfortunately never spent the time to codify how we would deliver on these concepts. Rather, we have relied on an informal use of traditional free and open-source principles. Recently a situation has arisen that compromises some of these principles and thus the entire status of the project, creating consternation among many users and contributors. For this reason, a number of us have stepped up to create a new organizational structure, which we call "The Open SIMH Project", to be the keeper and provide formal governance for the SIMH ecosystem going forward. While details of the structure and how it operates are likely to be refined over time, what will not change is our commitment to maintaining SIMH as a free and open-source project, licensed under an MIT-style license as shown on the "simh" repository page. It is our desire that all of the past users and contributors will come to recognize that the new organizational structure is in the best interests of the community at large and that they will join us in it. However, this iproject as defined, is where we intend to contribute our expertise and time going forward. At this point, we have in place the following, although we foresee other resources being added in the future as we identify the need and execute against them: A Github "organization" for the project at https://github.com/open-simh A Git repository for the simulators themselves at https://github.com/open-simh/simh The license for the SIMH simulator code base, found in LICENSE.txt in the top level of the "simh" repository. The "SIMH related tools" in https://github.com/open-simh/simtools. This is also licensed under MIT style or BSD style open source licenses (which are comparable apart from some minor wording differences). A "SIMH Steering Group" -- project maintainers and guides. The conventional git style process is used for code contributions, via pull request to the project repository. The Steering Group members have approval authority; this list is likely to change and grow over time. By formalizing the underlying structure, our operational principles and guidance can best benefit the community. These are being developed and formalized, with a plan to publish them soon. We have used our best judgment in setting up this structure but are open to discussion and consideration of other ideas, and to making improvements. Many of us have been part of different projects and understand that past mistakes are real. We have tried to learn from these experiences and apply the collected wisdom appropriately. We desire to hear from the community as we update and refine the operating structure for the Open SIMH project. We hope for your patience and look forward to your support as we work to refine the organization and be able to provide this wonderful resource for anyone to use as we continue to evolve the technology provided by the SIMH system. The SIMH Steering Group Clem Cole Richard Cornwell Paul Koning Timothe Litt Seth Morabito Bob Supnik ᐧ ᐧ ᐧ

2 years, 1 month

Please move the SIMH discussion to COFF

by Warren Toomey

Hi all, I think it's time to move the (no longer) SIMH discussion over to the COFF mailing list. The S/N ratio is dropping and we are straying too far away from the Unix side of things. Many thanks! Warren

2 years, 1 month

Re: [TUHS, groff] 1981 edition of AT&T Nroff/Troff User's Manual

by Douglas McIlroy

> https://www.tuhs.org/Archive/Documentation/Manuals/Unix_4.0/Volume_1/C.1.2_… Since PDF didn't exist in 1981, the document is either a scan or the result of a recent *roff run on ancient source. If it was made from source, it's an impressive testimonial to the longevity and stability of troff. Most probably it's a scan, in which case we owe many thanks to the public-spirited person who digitized this trove. Was it you, Arnold? Doug

2 years, 1 month

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TUHS June 2022