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6534 discussions

Any reason the removal/renaming of read-only registers should be permitted?

by Douglas McIlroy

I think Clark was justified in deviating from Ossanna. The prime rationale for allowing removal of read-only registers is uniformity--a powerful argument. It simplifies documentation and relieves a burden on users' understanding. It probably simplifies the code, too. This kind of special-casing is AI in the service of some perception that "no one would want to do that.". If "that" is the clear meaning of some specified action, then so be it. We are not dealing with physical hazards here. > even if they don't screw up the formatter internally, > they will become unrecoverably useless for documents > and macro packages, The same argument could be made about \applying .rm to any standard request, and I would disagree for the same reason as above. (A disappointing experimental discovery in this regard: .de seems to be immune to removal.) A change that I *would* welcome is warning about writing into a read-only register. (Also make .rm work on .de--a near reversal of the original proposal.) Doug

2 years, 2 months

BSD question: Kurt Shoens, or Kurt Schoens?

by Steffen Nurpmeso

Hello. Even in these rusty times (oh what complicated chemical processes there are!) a question that i hope someone can answer. In both Spinellis' UNIX history repo as well as the CSRG one (via robohack/ucb-csrg-bsd.git) one can find two ways of writing Kurt Shoen's name, and whereas i, who always refer to Mail and its "usr.bin/mail/def.h" (aac48ec10b56f59b321fb033a36bca2114ef061b): [ Author: Kurt Shoens <kas> AuthorDate: 1980-10-08 08:53:34 -0800] + * Author: Kurt Shoens (UCB) March 25, 1978 one can find the name "Kurt Schoens" as early as 4.2 BSD (curses, twinkle1), and then in a growing number of files, especially after 1993 when Keith Bostic and then Kirk McKusick did admin/admin/contrib/address.list and admin/admin/contrib/contrib and share/man/man0/title.cdrom But one can also see the commit Author: Kurt A. Schoens <kas(a)ucbvax.Berkeley.EDU> AuthorDate: 1980-10-09 02:48:47 -0800 and that is strange, as i presume all-automatic version control conversions here? Schoens .. is a bug? Thank you. --steffen | |Der Kragenbaer, The moon bear, |der holt sich munter he cheerfully and one by one |einen nach dem anderen runter wa.ks himself off |(By Robert Gernhardt) |~~ |..and in spring, hear David Leonard sing.. | |The black bear, The black bear, |blithely holds his own holds himself at leisure |beating it, up and down tossing over his ups and downs with pleasure |~~ |Farewell, dear collar bear

2 years, 2 months

Revisiting 6th Edition: rxv64

by Dan Cross

I've mentioned tangentially this a few times, but over the weekend I finally got around to dusting off the code and getting it running: https://github.com/dancrossnyc/rxv64.git rxv64 is a rewrite of MIT's xv6, which in turn, reimagines 6th Edition as a purely pedagogical system, implemented in ISO C for 32-bit SMP x86 machines. Building on xv6, rxv64 is implemented in Rust and targets 64-bit x86_64. It works well enough to boot up, run a shell, and run commands, but it doesn't really have much of a userland at present. I started this as a pedagogical tool, being something that one could point working engineers at as an example of a "real" operating system implemented on real hardware in Rust. The code could surely be made safer and more comprehensible, but cycles are short at present, and it's better to just get it out there. Have fun. - Dan C.

2 years, 2 months

I have unsubscribed my original address from the list

by Gregg Levine

Hello! For some time now I've had both this address, and my original address which was on another service altogether subscribed to this list. And starting some time earlier, it would not show a full thread, it would show partial contents, the latest was the work by Dan Cross. In fact With that being last, ah, straw I decided to do that. ----- Gregg C Levine gregg.drwho8(a)gmail.com "This signature fought the Time Wars, time and again."

2 years, 2 months

Re: UNIX "Machine Layer"

by Steve Simon

“soldering iron…” i do remember the fun of changing the baud rate of an async line on the Honeywell level 66 mainframe at college. This required shutting the whole machine down, removing one of the cards, and the (very careful) use of a wire wrap tool. -Steve

2 years, 2 months

UNIX Usage for Bell Telecom Typesetting

by segaloco

Good evening folks, I'm doing some research lately into the typesetting style apparent in the various UNIX System V guides I've scanned to archive.org. Their typesetting style is unlike that of the MM papers published with 3.0 and 4.0, but the contents seem to have continuity with the text in these collections. Well, in my searches sometimes telecom documents from the Bell System come up too and in materials from the 70s and 80s I started noticing that familiar typesetting in telecom stuff such as that hosted here https://www.telephonecollectors.info/index.php/browse/bsps-bell-system/bsp-… The earliest example I could find is 1969, so certainly at least a publication style that predates UNIX, but what I can't tell from my searches alone is if this style implies some non-UNIX typesetting system through and through or if there was a macro package dreamed up at some point between 1969 and 1982 that was in place by the time of the System V documentation. Just to detail specifics of the publication style, the commonalities I've found are the use of specifically bold numbers for page numbers, having the doc title and call number in the outer upper corner of pages, and just the fonts themselves look very similar. As an added note, the fonts used in the telecom documents and System V guidance documentation also resemble those in the copyright statement pasted on the cover of the extant PDF of the fifth edition UNIX manual. There is also some resemblance to the visual style observable in USG Program Generic and adjacent documentation (for instance the 1976 kernel description of PG 2 or the MERT 0 documents). This typesetting style is not seen in known research, CB, nor PWB until 5.0. Was there some separate typesetting system used in the broader System that, say, WECo may have taken up when they took over documentation between 3.0 and SVR2? - Matt G.

2 years, 2 months

S2-bits V2 Source Code Restoration

by segaloco

Hi folks, sharing another project that I've been tinkering on for a little bit since I like having a lot of irons in the fire: https://gitlab.com/segaloco/v2src After the link is a repository which over time will be accumulating the results of disassembly and analysis of files found in the s2-bits.tar.gz file in the archive. Details of my process are contained in the repository's readme. The short of it is I'm disassembling the binaries one by one, and where possible am comparing them with known sources to massage these into a pretty close restoration of the original sources. A few discoveries I've made in the process thus far: - These binaries appear to represent a version between the first and second editions. The binaries themselves are a mix of "naked" binaries as well as V1 and V2 a.out formats. Where it matters, things are much closer in character to V2 than V1. - All section 1 content that would be gone by V2 is removed here. Curiously, mount(1), type(1), and umount(1) which are in both V1 and V2 are absent from the s2-bits. - The sources marked "V2" in the UNIX source tree may be a bit closer in character to V3. Notable examples are that, while string references to /etc/uids remain, all data references have been updated to /etc/passwd, and several mathematical operations in the disassembled binaries map to KE-11 Extended Arithemtic Element registers where in the sources labeled "V2" in the tree have instead shifted to doing these calculations differently, presumably as these sources target the 11/45, not the 11/20. Additionally, the cat.s in "V2" on the tree contains the '-' stdin option, which was first documented in V3. The most likely story is that they're somewhere between, just like the s2-bits are between V1 and V2, but all of these observed differences thus far have aligned the sources with their descriptions in the third edition manual. Anywho, as usual, if anyone spots anything amiss or that could be done better, happy to accept contributions, or fork it and tinker away. Also, if anyone has already done this, speak up and tell me now so I don't double up on something so involved =P - Matt G.

2 years, 2 months

Re: UNIX "Machine Layer" Standards

by jnc＠mercury.lcs.mit.edu

> From: Paul Ruizendaal > something like a boot rom only became the norm in the late > 70's. Before that, one keyed in two dozen words with a tiny program to > load the first boot stage. A little wrong on that date. Even the PDP-11/20 (the first -11) had a boot ROM: https://gunkies.org/wiki/BM792_ROM which appreared in mid-1971 (about a year after the release of the /20). DEC sold them pre-programmed, but one could 'program' one onself, if one wanted - with a soldering iron! (Check out the image! I actually did that to one that I was given, that had been eviscerated by someone.) From then on (follow the category link), the rest used PROM chips. > From: Warner Losh > Oftentimes, the interrupt vector was in the lowest core addresses It's worth remembering that in the early period, that restriction to low addresses was built into the hardware (in an amusing way :-). Take the DL11: https://gunkies.org/wiki/DL11_asynchronous_serial_line_interface which was sort of mandatory as the 'console' serial interface on most early -11's (until the DL11-W appeared; more on its big improvement in a second). It set the interrupt vector with _jumpers_. (You want to change the interrupt vector? Dig out your soldering iron! :-) There were only 6 jumpers - one each for address bits 3 through 8. So the largest vector you could set was 0770. The DL11-W was a big step forward - it replaced the jumpers with a DIP switch! :-) Still only six bits, though. :-) Noel

2 years, 2 months

Re: UNIX "Machine Layer" Standards

by Paul Ruizendaal

Hi Matt, I’ve responded on list about the early unix development process as I understand it, but I want to avoid discussing things that are not directly related to the history of Unix. Hence this PM as well. > Where I'm trying to put this sort of knowledge into use is I'm starting to spec out a kernel bootstrap for the RPi Pico and Pine64 Ox64 boards (ARM32 and RISCV64 respectively) that is not only sufficient to start a V7-ish kernel on each, but that are ultimately based on the same design, varying literally only where the hardware strictly necessitates it, but similar enough that reading the two assembly files side by side yields essentially the exact same discrete operations. I have a similar interest, working with early Unix and modern RiscV hardware for a compare and contrast experience. - My development targets are (i) an FPGA based RV32 SoC implementation, (ii) a Sipeed D1 RV64GC board and shortly (iii) a Pine64 Pinetab-V. - My software targets are: (a) xv6-rv, (b) SysIII, (c) Linux, (d) experiments around SysIII Linux is for me a secondary target, just for comparison and to see if ideas are “Linux capable”. I’m not overly interested in Arm at the moment. My ideas are still evolving, but currently more or less along the below lines: - Boot rom loads SPL, this is custom in each case and set by the SoC's designers. - SPL initialises DRAM system and loads next stage. Unfortunately, this too would seem to be quite system specific, but the BSP should provide the baseline for this. As BSP’s are often a mess, milage may vary. - The next stage is a hybrid of BBL, OpenSBI and Virtio. The idea is to provide a standard abstraction layer that all of my software targets can work with. This idea is used for the FPGA target and allows booting a Linux kernel with just the generic Virtio device drivers (so far just disk and console). - The last layer is the classical OS layer. If I get it right, each OS can run on all h/w targets without customisation. At the moment I’m playing with USB, and how that might layer into the structure of V7, SysIII or 8th Edition -- and also the above.

2 years, 2 months

Re: UNIX "Machine Layer" Standards

by Paul Ruizendaal

> Date: Mon, 10 Apr 2023 18:27:51 +0000 > From: segaloco > ... or was there no single guiding principle and each machine came up, at that level at least, in a relative vacuum, with only the machine interface to UNIX being the guiding principle? I stumbled into the same question last year, when doing my SysIII to RV64 port. I managed to turn that into a somewhat chaotic discussion, mixing old and new, and history with ideas. From that chaotic discussion I got the impression that it was indeed mostly ad hoc. In context, hardware was much easier to boot and drive back then -- it probably was not seen as complex enough to warrant much research into layering and abstraction. Also bear in mind that something like a boot rom only became the norm in the late 70’s. Before that, one keyed in two dozen words with a tiny program to load the first boot stage. That said, there is an implicit layering in v7 and beyond: - “low.s" does hardware setup, incl. such stuff as setting up interrupt tables. As this is closely tied to the hardware, it would have been a custom job in each case. - “mch.s” (later also mch.c) has the basic routines that are hardware dependent (switching stacks, changing priority levels and modes, etc.). It also has emulation for ‘missing’ instructions, such as floating point ops where this is not available in hardware. Same as above, I think. Maybe h/w related memory protection operations should live here as well, but the hardware was still quite divergent in this area in the 70’s and early 80’s. - low-level device drivers live in the ‘dmr’ or (later) ‘io’ directory. Here there is some standardisation, as all device drivers must conform to the (char/block) device switch APIs. It seems to me that most of these drivers were written by taking one that was similar to what needed to be written and to start from there. Maybe this is still how it works in Linux today. - To the extent that there is such a thing as 'high-level device drivers’ in early Unix, the structure is less clearly visible. The file system (and there was only one at the time of v7) is placed between the block device switch and the mount table so to speak. This was structured enough that splicing in other file systems seems to have been fairly easy in the early 80’s (the splicing in, not the writing of the file system itself, of course). Starting with 8th edition, the ‘file system switch’ created a clear API for multiple file systems. Arguably, the ‘tty’ subsystem is also a ‘high-level device driver’, but this one lives as custom code together with the serial port device drivers. Also in 8th Edition, ‘streams' were introduced. One could think of this as a structured approach to high-level device drivers for character mode devices, incl. the ’tty’ subsystem. - I don’t think there was ever anything in early Unix that merged ’streams’ and the 'file system switch' into a single abstraction (but maybe 9P did?). > Where I'm trying to put this sort of knowledge into use is I'm starting to spec out a kernel bootstrap for the RPi Pico and Pine64 Ox64 boards (ARM32 and RISCV64 respectively) that is not only sufficient to start a V7-ish kernel on each, but that are ultimately based on the same design, varying literally only where the hardware strictly necessitates it, but similar enough that reading the two assembly files side by side yields essentially the exact same discrete operations. I have a similar interest, but to avoid the same chaos as I created before, I’ll respond to this with a pm.

2 years, 2 months

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