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6532 discussions

Re: [TUHS] {TUHS] Interesting Commentary on Unix from Multicians

by Douglas McIlroy

> Single Level Storage is an awesome concept and removes so many ugly > hacks from algorithms that otherwise have to process data in files. This was Vic Vyssotsky's signature contribution to Multics, though in typical Vyssotsky fashion he never sought personal credit for it. Other awesome Vyssotsky inventions: BLODI (block diagram), the first data-flow language, for sample-data systems. Parallel flow analysis (later reinvented and published by John Cocke). Vic installed this in Fortran to produce diagnostics such as, "If the third branch of IF statement 15 is ever taken, then variable E will be used before being set". Darwin, the original game of predation and self-reproduction among programs. Corewars.org keeps a descendant version going 60 years later. A minimum-spanning-tree algorithm quite different from the well-known methods due to his colleagues Bob Prim and Joe Kruskal, again unpublished. Not long ago on TUHS, Andrew Hume told how Vic found the same isolated bug in dc by mathematically generating hard cases that Andrew stumbled on by accident, As you may infer, Vic is one of my personal computing heroes. Doug

3 years, 1 month

Armando plate

by Steve Bourne

Armando also responsible for the UNIX "live free or die" plates. I still have a few. Steve

3 years, 1 month

conventions around zero padding in ip4

by ron minnich

I first learned in the 80s that 127.1 meant 127.0.0.1. I always assumed zero padding was defined in a standard *somewhere*, but am finding out maybe not. I talked to the IP OG, and he tells me that padding was not in any standard. [side note: it's weird and wonderful to still have so many people "present at the creation" of computing as we know it still around, and to find they are so willing to answer naive questions!] Padding is a standard in ip6, possibly because the addresses are so long. :: is your friend. IP4 padding came up recently: the ip command interprets 10.2 as 10.2.0.0, whereas most things (golang libraries, ping, ...) interpret it as 10.0.0.2. The latter interpretation accords with what I learned 40y ago. But, I find myself wondering: where was the first use of the IP4 zero padding convention?

3 years, 1 month

TUHS web server has changed

by Warren Toomey

Hi all, I've just changed the DNS CNAME record of www.tuhs.org from minnie.tuhs.org (45.79.103.53) to newmin.tuhs.org (50.116.15.146). Minnie is running Ubuntu 18.04LTS and is getting a bit long in the tooth. Newmin is running 22.04LTS. So far I've got the web service up and running on newmin. Doing the e-mail migration will be fun :-) Let me know if you spot anything wrong with the new web server. I've also set up oldwww.tuhs.org which points at minnie, so you can still get to things on the old server. Cheers, Warren

3 years, 1 month

Re: [TUHS] conventions around zero padding in ip4

by jnc＠mercury.lcs.mit.edu

> There were other ways of specifying a IP address numerically, initially; I decided to set the Way-Back Machine to as close to 0 as I could get, and looked to see what the Terminal Interface Unit: https://gunkies.org/wiki/Terminal_Interface_Unit whose source I recently recovered, did. This is an interesting implementation, because it was definitely one of the first 4 TCP implementations done (before any UNIX ones); likely one of the first two, along with the TENEX one. (Actually, they both likely originally predate the split of TCP and IP into separate protocols, although this version post-dates that split.) The manual: http://ana-3.lcs.mit.edu/~jnc/tech/mos/docs/tiunv1.lpt (in "B. TELNET Commands") and the source: http://ana-3.lcs.mit.edu/~jnc/tech/mos/tiu/telnet-1.mac disagree on how the user gave addresses in numeric form in an 'open' command; both agree that it was '@O <rest>,<net>,<socket>', but the manual claims that 'rest' "may be specified symbolically, or numerically in decimal", but the code shows that '#xxx' could also be used, to give it in hex. (Although if hex were used, the number could be a max of 16 bits; decimal alloweded up to 42 bits.) > From: Michael Kjörling > Looks like [A/B/C addresses] happened in 1978 or thereabouts? > https://www.rfc-editor.org/ien/ien46.txt No; it post-dates the IEN era; "Assigned Numbers" of September 1981 (RFC-790) is the first mention I could find of it. (That Dave Clark IEN is talking about what later became 'IP subnets' - which ironically long pre-date A/B/C - see IEN-82, February 1979.) The Internet Protocol spec of September 1981 (RFC-791) also has A/B/C; my memory is that this change was _not_ discussed in the INWG, Postel just sprung it on us in these two RFCs. I suspect what happened is that Jon (as keeper of the network numbers) realized that there was an increasing demand for network numbers, and 256 would only last so long, so he sprung into action and did the A/B/C thing. (If this topic is of more interest, it should get moved to the 'internet-history' list, it's off-topic here.) Interestingly, RFC-790 says: "One notation for internet host addresses commonly used divides the 32-bit address into four 8-bit fields and specifies the value of each field as a decimal number with the fields separated by periods." Note the "one notation", implying that it wasn't any kind of standard at that point. Noel

3 years, 1 month

Re: [TUHS] conventions around zero padding in ip4

by jnc＠mercury.lcs.mit.edu

> From: Ron Minnich > I first learned in the 80s that 127.1 meant 127.0.0.1. I always assumed > zero padding was defined in a standard *somewhere*, but am finding out > maybe not. I talked to the IP OG, and he tells me that padding was not > in any standard. I don't think it was very standardized; I've been working on the Internet since 1977, and this is the very first I ever recall hearing of it! :-) > From: Bakul Shah > The converse question is who came up with the a.b.c.d format where each > of a,b,c,d is in 0..255? Again, that was not standardized at an early stage, but was, as best I can now recall, just adopted by general usage (i.e. without any formal discussion). There were other ways of specifying a IP address numerically, initially; e.g. for a while at MIT we were using w,x,y,z (with w-z in octal - note the ','s, which were a syntatic tag for the octal form), which was easier to interpret when looking at a packet dump on a PDP-11. Here: http://ana-3.lcs.mit.edu/~jnc/tech/unix/arc/tftp.c.1 is the source for a user command (from July, 1979) which allowed host addresses to be given in that form. I'm not sure who came up with the dotted decimal form; I suspect you'd need to find some really old email archives, and look in that. There was, early on, a list called "tcp-ip", used by people who were getting their machines ready for the NCP->TCP/IP conversion. However, I suspect the 'dotted quad' predates that; there was an even earlier mailing list, used in early experimental work, by the group working on internet technology, whose name escapes me (it was something like "internet working group"). It's possible that an IEN: https://www.rfc-editor.org/ien/ien-index.html might mention the 'dotted quad' syntax; TCP and IP meeting minutes would be a good place to start. Noel PS: The A/B/C addresses are actually a moderately late stage of IP addresses. At the very start, they were all '8 bits network numbers, and 24 bits of 'rest''.

3 years, 1 month

Re: [TUHS] Alternative Implementation Proposal for Unix/370 (BTL, 1979)

by jnc＠mercury.lcs.mit.edu

> From: Tom Lyon > there were a few icustomer nstallations. Bell Labs Indian Hill was one > - so that's why TSS was the base of their UNIX port. "A UNIX System Implementation for System/370" (by W. A. Felton, G. L. Miller, and J. M. Milner): https://www.bell-labs.com/usr/dmr/www/otherports/ibm.html says "code to support System/370 I/O, paging, error recording and recovery, and multiprocessing already existed in several available operating systems, we investigated the possibility of using an existing operating system, or at least the machine-interface parts of one, as a base to provide these functions for the System/370 implementation ... Of the available systems, TSS/370 came the closest to meeting our needs and was thus chosen as the base for our UNIX system implementation". Alas, it doesn't say which other systems were also considered. >> On May 6, 2022, at 09:39, arnold(a)skeeve.com wrote: >> So, why, given the letter from these folks, including DMR, did they go >> ahead and use the TSS solution anyway? That paper says: "We initially thought about porting the UNIX operating system directly to System/370 with minimal changes. Unfortunately, there are a number of System/370 characteristics that, in the light of our objectives and resources, made such a direct port unattractive. The Input/Output (I/O) architecture of System/370 is rather complex; in a large configuration, the operating system must deal with a bewildering number of channels, controllers, and devices, many of which may be interconnected through multiple paths. Recovery from hardware errors is both complex and model-dependent. For hardware diagnosis and tracking, customer engineers expect the operating system to provide error logs in a specific format; software to support this logging and reporting would have to be written. ... Finally, several models of System/370 machines provide multiprocessing, with two (or more) processors operating with shared memory; the UNIX system did not support multiprocessing." Presumably these factors outweighed the factors listed in the Haley/London/Maranzaro/Ritchie letter. Noel

3 years, 1 month

Alternative Implementation Proposal for Unix/370 (BTL, 1979)

by Tom Lyon

I was (re?)introduced to Chuck Haley recently and discovered he had a copy of a Bell Labs memo from himself, London, Maranzaro, and Ritchie. They suggest that the path pursued to get UNIX running in/under TSS/370 was the hard way to go. Enjoy: http://charles.the-haleys.org/papers/Alternate_Implementation_Proposal_for_… -- - Tom

3 years, 1 month

tuhs hiccups?

by Tom Lyon

For some reason, against my wishes, I'm not getting TUHS messages as they happen, but in batches (not digest) after 5-7 days. Last I've received right now is from May 2. Anyone know why? -- - Tom

3 years, 1 month

Bob Widlar Poster

by Janek Gál

Hey folks, there is a cool poster by Bob Widlar, which we would like to have as a big poster in the hackspace: https://august.sax.de/widlar.jpg This is already a high resolution scan (2048 × 3048) but we are looking for something better (for A0 paper). Does anyone have something like this maybe still in his collection? greetings, Janek :) -- Janek Gál <janek(a)sax.de> Dresden, Germany http://www.sax.de

3 years, 1 month

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