TUHS December 2017

tuhs@tuhs.org

82 participants
93 discussions

by norman＠nose.cita.utoronto.ca

I've assembled some notes from old manuals and other sources on the formats used for on-disk file systems through the Seventh Edition: http://www.cita.utoronto.ca/~norman/old-unix/old-fs.html Additional notes, comments on style, and whatnot are welcome. (It may be sensible to send anything in the last two categories directly to me, rather than to the whole list.)

1 year, 11 months

Happy birthday, John von Neumann!

by Dave Horsfall

We gained John von Neumann on this day in 1903, and if you haven't heard of him then you are barely human... As computer science goes, he's right up there with Alan Turing. There is speculation that he knew of Babbage's work; see https://cstheory.stackexchange.com/questions/10828/the-relation-between-bab… . -- Dave Horsfall DTM (VK2KFU) "Those who don't understand security will suffer."

6 years, 2 months

origin of C header files

by Wesley Parish

Hi I've just had an interesting experience, explaining C header files to a nephew programmer who didn't understand them. I pointed him in the direction of Minix as an example of a small well-engineered system which would display their use. Which raised the question: when did header files come into use? Who was the first to use header files to store common system-wide or application-wide data definitions? Was it used in any languages prior to C? Thanks Wesley Parish

6 years, 3 months

Some resources for V6/PDP/SIMH newbs like me

by Will Senn

All, While it's fresh, I thought I'd share some resources I've found helpful in learning about the venerable v6 as a relative newb... Learning Unix V6 in the modern era is an interesting and enormously educational experience. In the process of using it I have had to learn how to host it in a simulator (SimH in my case, but there are others), install it, communicate with it, configure it, build special files for it, attach devices to it, communicate with the devices attached to it and to SimH, build a kernel, install the kernel, boot the kernel, work with a variety of media intended to work with it, extend it, and so on. In addition, I have had to learn a bit about the PDP-11 (as arguably the most convenient architecture for learning about V6), about its architecture, its instruction set, its devices, its memory structure, and so on. None of this exploration would have been possible without the excellent work of Bob Supnik, Mark Pizzolato, and co. on the SimH pdp-11 simulator, the Simh mailing list, Warren Toomey and TUHS for making the bits available, the TUHS mailing list, PUPS, Bitsavers, and a slew of readily available documentation and texts including these notables: Setting Up Unix 6th Edition from the V6 Programmer's Manual The Unix V6 Programmer's Manual in its entirety The SimH and SimH PDP-11 Manuals A large number of blogs with SimH specific V6 installation logs The V6 Source Code and man pages (don't forget to install man - the 1bsd version works, and is superior)! The DEC PDP-11/05-10-35-40 1973 Handbook (the 11/40 handbook is not as detailed with respect to memory management) Lions's Commentary on the Sixth Edition source code Now that I'm over the beginner's hump, so to speak, I'm exploring things differently and I thought I'd share some resources that I am currently finding useful and interesting in my explorations... To bone up on assembly language, Lions's commentary is exceptionally helpful in explaining assembly as it is implemented in V6. The manual itself is really thin, and the source is a bit cryptic, for the newcomer. Lions explains the idioms used in the main source of V6. However, without a background in assembly language, Lions is pretty meaningless, so I went looking for something that was PDP specific that would bridge the gap and help me understand Lions's words. I found a number of texts that were really good. Most require a working RT11 instance to actually try out the coding examples and do the exercises (SimH and Bitsavers to the rescue): Arthur Gill - Machine and Assembly Language Programming of the Pdp-11 Charles A. Kapps and Robert L. Stafford - Assembly Language for the PDP-11 Glenn H. MacEwan - Introduction to Computer Systems: Using the PDP-11 and Pascal James F. Peters - The Digital Way: Macro-11 Assembler Programming (PDP-11) Michael G. Schneider - The Principles of Computer Organization: With Assembly Language Programming for the PDP-11 PDP-11 Processor Handbook (pretty much any edition) Thomas A. Frank - Introduction to the PDP-11 and its Assembly Language All of these are useable with a running RT11 instance. But, I think the Peters and Frank books are the standouts. Peters because all of the exercises that I have tried (dozens) have worked as printed and Frank because he is rigorous in his treatment of the subject and builds up from digital logic all the way through program execution. Frank is an excellent complement to Lions work because he explains the details that Lions assumes. To learn about digital logic, and a special thanks to Warren for his work on Crazy Small CPU, I have been introduced to logisim. It is a great playground for exploring digital logic. I had no idea that a sketchpad for digital logic simulation was available and accessible to the layperson. Logisim development stopped around 2014 and while there are a number of successors out there, I am using logisim-evolution: https://github.com/reds-heig/logisim-evolution The rabbit trails never seem to end... in order to learn how to use logisim, I went through the excellent tutorial and then went looking for a book of experiments in digital logic and found: digital computer lab workbook from 1969 http://bitsavers.trailing-edge.com/pdf/dec/handbooks/Digital_Computer_Lab_W… digital equipment corporation computer lab teacher's guide from 1968 http://www.so-much-stuff.com/pdp8/pdf/ComputerLabTeachersGuide.pdf These two are useable with very little modification as a source of digital logic exercises that work great with logisim and are related to the architectural lineage of the PDP-11. These resources fit together nicely in my pursuit to better understand digital logic, the pdp-11, assembly language, and unix v6. In sum: Source code for v6 for what really is supposed to happen in v6 operation Lions for understanding Unix V6 sources and for unix assembly language information PDP-11 Hanbook for quick reference on PDP-11 assembly language instruction set Frank for assembly language details and for details on digital logic and its relationship to the PDP-11 architecture. Logisim to test logic constructs The digital lab workbook for practice with digital logic Later, Will -- GPG Fingerprint: 68F4 B3BD 1730 555A 4462 7D45 3EAA 5B6D A982 BAAF

6 years, 3 months

Re: [TUHS] OT: Grace Hopper, Unix epoch, ARPAnet converted to TCP/IP

by jnc＠mercury.lcs.mit.edu

> From: Dave Horsfall <dave(a)horsfall.org> > the ARPAnet got converted from NCP to TCP/IP in 1983; ... have a more > precise date? No, it was Jan 1. It wasn't so much a 'conversion', as that was the date on which, except for a few sites which got special _temporary_ dispensation to finish their preparations, support for NCP was turned off for most ARPANET hosts. Prior to that date, most hosts on the ARPANET had been running both, and after that, only TCP worked. (Non-ARPANET hosts on the then-nascent Internet had always only been using TCP before that date, of course.) Noel

6 years, 3 months

OT: Grace Hopper, Unix epoch, ARPAnet converted to TCP/IP

by Dave Horsfall

Some interesting historical stuff today... We lost Rear Admiral Dr. Grace Hopper USN (Retd) in 1992; there's not much more than can be said about her, but I will mention that she received (posthumously) the Presidential Medal of Honor in 2016. As every Unix geek knows, today is the anniversary of The Epoch[tm] back in 1970, and at least one nosey web site thinks that that is my birthdate too... And according to my notes, the ARPAnet got converted from NCP to TCP/IP in 1983; do any greybeards here have a more precise date? -- Dave Horsfall DTM (VK2KFU) "Those who don't understand security will suffer."

6 years, 3 months

Re: [TUHS] Why did PDPs become so popular?

by Larry McVoy

On Fri, Dec 29, 2017 at 04:04:01AM -0700, Kevin Bowling wrote: > Alpha generally maintained integer/ALU and clockspeed leadership for > most of the '90s > http://www.cs.columbia.edu/~sedwards/classes/2012/3827-spring/advanced-arch… Wow, that first graph is the most misleading graph on CPU performance I've ever seen. Ever. So from 1993 to 2000 the only CPUs released were Alphas? That era was when I was busy measuring performance across cpus and operating systems and I don't ever remember any processor being a factor of 2 better than its peers. And maybe I missed it, I only owned a couple of alpha systems, but I never saw an Alpha that was a game changer. Alpha was cool but it was too little, too late to save DEC. In that time period, even more so now, you had to be 2x better to get a customer to switch to your platform. 2x cheaper 2x faster 2x more reliable Do one of those and people would consider switching platforms. Less than that was really tough and it was always, so far as I remember, less than that. SMP might be an exception but we went through that whole learning process of "well, we advertised symmetric but when we said that what we really meant was you should lock your processes down to a processor because caches turn out to matter". So in theory, N processors were N times faster than 1 but in practice not so much. I was very involved in performance work and cpu architecture and I'd love to be able to claim that we had a 2x faster CPU than someone else but we didn't, not at Sun and not at SGI. It sort of make sense that there weren't huge gaps, everyone was more or less using the same sized transistors, the same dram, the same caches. There were variations, Intel had/has the biggest and most advanced foundries but IBM would push the state of the art, etc. But I don't remember anyone ever coming out with a chip that was 2x faster. I suspect you can find one where chip A is introduced at the end of chip B's lifespan and A == 2*B but wait a few month's and B gets replaced and A == .9*C. Can anyone point to a 2x faster than it's current peers chip introduction? Am I just not remembering one or is that not a thing? --lm

6 years, 3 months

Re: [TUHS] Why did PDPs become so popular?

by Rudi Blom

A bit off the PDPs, but to do a minor correction on mail below The commercial version of 'UNIX' on Alpha was maybe first called Digital Unix OSF/1, but quickly changed to Digital Unix at least with v3 and v4.0 (A - G). From there we had a 'break' which only in part was due to take over by Compaq and we had Tru64 UNIX v5.1A and V5.1B. The V5.1B saw updates till B-6. As for the Digital C compiler, I'm still using DTCCMPLR650 installed Compaq C Version 6.5 for Compaq Tru64 UNIX Systems When I get some old source (some even developed on SCO UNIX 3.2V4.2) I like to run it through all compiler /OS-es I got handy. With the Compaq C compiler and HP-UX ANSI C I mostly get pages of warning and a few errors. By the time I 'corrected' what I think is relevant some nasty coredumps tend to disappear :-) Compile for a better 2018, uncle rubl >Date: Fri, 29 Dec 2017 21:30:11 -0500. >From: Paul Winalski <paul.winalski(a)gmail.com> >To: Ron Natalie <ron(a)ronnatalie.com> >Cc: TUHS main list <tuhs(a)minnie.tuhs.org> >Subject: Re: [TUHS] Why did PDPs become so popular? >Message-ID: <CABH=_VRwNXUctFPav5rHX83wfUS0twMQuBhinRZ6QEY1cB3TNQ(a)mail.gmail.com> Content-Type: text/plain; charset="UTF-8" > >On 12/29/17, Ron Natalie <ron(a)ronnatalie.com> wrote: > The Alpha was hot > stuff for about nine months. Ran OSF/1 formerly DigitalUnix formerly > OSF/1. >Digital UNIX for the VAX was indeed derived from OSF/1. The port to >Alpha was called Tru64 UNIX. >Tru64 UNIX was initially a pure 64-bit system, with no provision for >building or running 32-bit program images. This turned out to be a >mistake . DEC found out that a lot of ISVs had code that implicitly >"knew" that sizeof() a pointer was the same as sizeof(int) was the >same as 4 bytes. Tru64 was forced to implement a 32-bit compatibility >mode. >There was also a problem with the C compiler initially developed at >DECwest in Seattle. It supported ONLY ANSI standard C and issued >fatal errors for violations/extensions of the standard. We (DEC >mainstream compiler group) called it the Rush Limbaugh >compiler--extremely conservative, and you can't argue with it.

6 years, 3 months

Re: [TUHS] origin of C header files

by Doug McIlroy

Warning: off-topic info > I was told once that McIlroy and Morris invented macro instructions > for assembly language. And certainly they wrote the definitive > paper on macros, with, as I recall, something like 10 decisions you > needed to make about a macro processor and you could generate 1024 > different macro systems that way. I wonder if that ever got > published The suggestion that I invented macros can also be found on-line, but it's not true. I learned of macros in 1957 or before. GE had added a basic macro capability to an assembler; I don't know whether they invented the idea or borrowed it. In 1959 George Mealy suggested that Bell Labs install a similar facility in SAP (SHARE assembly program). Doug Eastwood wrote the definition part and I handled expansions. Vic Vyssotsky later asked whether a macro could define a macro--a neat idea that was obviously useful. When we went to demonstrate it, we were chagrinned that it didn't work: definition happening during expansion resulted in colliding calls to a low-level string-handling subroutine that was not re-entrant. Once that was fixed, Steve Johnson (as a high-school intern!) observed that it allowed the macro table to serve as an addressable memory, for which the store and load operations were MOP (macro define) and MAC (macro call). Probably before Steve's bright insight, Eastwood had folded the separate macro table into the opcode table, and I had implemented conditional assembly, iteration over a list, and automatic generation of symbols. These features yielded a clean Turing-complete language-extension mechanism. I believe we were the first to achieve this power via macros. However, with GPM, Christopher Strachey showed you don't need conditionals; the ability to generate new macro names is enough. It's conceivable, but unlikely, that this trick could be done with earlier macro mechanisms. As for publication, our macroprocessor inspired my CACM paper, "Macro nstruction extension of compiler languages", but the note that Steve remembers circulated only in the Labs. A nontrivial example of our original macros in action--a Turing machine simulator that ran completely within the assembler--was reproduced in Peter Wegner's programming book, so confusingly described that I am glad not to have been acknowledged as the original author. Doug

6 years, 3 months

Re: [TUHS] Why did PDPs become so popular?

by jnc＠mercury.lcs.mit.edu

> From: Paul Winalski > Lack of marketing skill eventually caught up to DEC by the late 1980s > and was a principal reason for its downfall. I got the impression that fundamentally, DEC's engineering 'corporate culture' was the biggest problem; it wasn't suited to the commodity world of computing, and it couldn't change fast enough. (DEC had always provided very well built gear, lots of engineering documentation, etc, etc.) I dunno, maybe my perception is wrong? There's a book about DEC's failure: Edgar H. Schein, "DEC is Dead, Long Live DEC", Berett-Koehler, San Francisco, 2003 which probably has some good thoughts. Also: Clayton M. Christensen, "The Innovator's Dilemma: When New Technologies Cause Great Firms to Fail", Harvard Business School, Boston, 1997 briefly mentions DEC. Noel

6 years, 3 months

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TUHS December 2017