TUHS

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6532 discussions

Re: [TUHS] Determining what was on a tape back in the day

by jnc＠mercury.lcs.mit.edu

> From: Will Senn > I think I understand- the bytes that we have on hand are not device > faithful representations, but rather are failthful representations of > what is presented to the OS. That is, back in the day, a tape would be > stored in various formats as would disks, but unix would show these > devices as streams of bytes, and those are the streams of bytes are what > have been preserved. Yes and no. To start with, one needs to differentiate three different levels; i) what's actually on the medium; ii) what the device controller presented to the CPU; and iii) what the OS (Unix in this case) presented to the users. With the exception of magtapes (which had some semantics available through Unix for larger records, and file marks, the details of which escape me - but try looking at the man page for 'dd' in V6 for a flavour of it), you're correct about what Unix presented to the users. As to what is preserved; for disks and DECtapes, I think you are broadly correct. For magtapes, it depends. E.g. SIMH apparently can consume files which _represent_ magtape contents (i, above), and which include 'in band' (i.e. part of the byte stream in the file) meta-data for things like file marks, etc. At least one of the people who reads old media for a living, when asked to read an old tape, gives you back one of these files with meta-data in it. Here: http://ana-3.lcs.mit.edu/~jnc/tech/pdp11/tools/rdsmt.c is a program which reads one of those files and convert the contents to a file containing just the data bytes. (I had a tape with a 'dd' save of a file-system on it, and wanted just the file-system image, on which I deployed a tool I wrote to grok 4.2 filesystems.) Also, for disks, it should be remembered that i) and ii) were usually quite different, as what was actually on the disk included thing like preambles, headers, CRCs, etc, none of which the CPU usually could even see. (See here: http://gunkies.org/wiki/RX0x_floppy_drive#Low-level_format for an example. Each physical drive type would have its own specific low-level hardware format.) So what's preserved is just an image of what the CPU saw, which is, for disks and DECtapes, generally the same as what was presented to the user - i.e. a pile of bytes. Noel

7 years, 7 months

Re: [TUHS] Determining what was on a tape back in the day

by jnc＠mercury.lcs.mit.edu

> From: Will Senn > So, I came across this tape: > ... > I was curious what was on it 'od' is your friend! If you look here: http://mercury.lcs.mit.edu/~jnc/tech/V6Unix.html#dumpf there's a thing which is basically 'od' and 'dd' rolled in together, which allows you to dump any block you want in a variety of formats (ASCII, 16-bit words in octal [very useful for PDP-11 binary], etc). I wrote it under CygWin, for Windows, but it only uses the StdIO library, and similar programs (e.g. my usassembler) written that way work fine under Losenux. Try downloading it and compiling it - if it doesn't work, please let me know; it'd be worth fixing it so it does work on Linux. > after some fiddling, I figured out that I could get a boot prompt (is > that actually from the tape?) The 0th block does seem to contain some PDP-11 binary - a bootstrap of some sort. I'll look in more detail in a bit. > I was thinking this was a sixth edition install tape of some sort, but > if it is, I'm not able to figure it out. >From what I can see, it's probably a tp-format tape: the 1st block contains some filenames which I can see in an ASCII dump of it: speakez/sbrk.s dcheck.c df.c intel/as80.c intel/optab.8080 > v7 and look at its content using tm or tp, but then I realized that I > didn't have a device set up for TU56 You don't need to mount it on DECTape drive - it's just blocks. Mount it as an RK05 image, or a magtape, or whatever. > When you received an unmarked tape back in the day, how did you go about > figuring out what was on it? Generally there would have been some prior communication, and the person sending it would have told you what it was (e.g. '800 bpi tar', or whatever). > What advice would you give a future archivist to help them quickly > classify bit copies of tapes :). Like I said: "'od' is your friend!"!! :-) Noel

7 years, 7 months

197[78] usenix conf. at columbia, magtapes "found in the street"?

by ron minnich

Random memories, possibly wrong. In 1977/78 I was at udel and had done a fair amount of work on unix but as a lowly undergrad did not get to go to the Columbia Usenix meeting. Ed Szurkowski of udel went. Ed was the grad student who did hardware design for 11s for Autotote (another story) but also stood up a lot of the early unix 11s at udel starting in 1976, starting with an 11/70. Mike Muus used to come up and visit us at udel and Mike and Ed would try to ask questions the other could not answer. Mike always had a funny story or two. Ed later went to Bell Labs and I lost track of him. The directions for the MTA were fairly clear: it listed a stop that you under no circumstances should get off at, and if you did get off at, you should not go up to the street, lest you never return. This was no joke. Some places in NY were pretty hazardous in those days. I *think* this was the meeting where Ken showed up with a bunch of magtapes, and Ed claimed that, in Ken's word, they were "... found in the street." This part I remember well: Ed returning with two magtapes and our desire to upgrade. We at udel, like many places, had done lots of our own mods to the kernel, which we wanted to keep. So we ran a diff between trees, and I wrote a merge with TECO and ed which got it all put together. I later realized this was a very early form of 'patch', as it used patterns, not line numbers, to figure out how to paste things back together. I really got to love regex in those years. Except for one file: the tools just would not merge them. Ed later realized there was one key difference that we had not noticed, a missing comment, namely, the Western Electric copyright notice ... I'm kinda sorry that our "udel Unix" is lost to the great /dev/null, it would be interesting to see it now. ron

7 years, 7 months

Re: [TUHS] Determining what was on a tape back in the day

by jnc＠mercury.lcs.mit.edu

> From: Clem Cole > stp is from the Harvard distribution. The MIT PWB1 system I have has the source; the header says: M. Ferentz Brooklyn College of CUNY September 1976 If it can't be found on TUHS, I can upload it. No man page, though. :-( Noel

7 years, 7 months

ed(1) and Pipes.

by Norman Wilson

Ralph Corderoy: ed(1) pre-dates pipes. When pipes came along, stderr was needed, and lots of new idioms were found to make use of them. Why didn't ed gain a `filter' command to accompany `r !foo' and `w !bar'? === I sometimes wonder that too. When I use `ed,' it is usually really qed, an extended ed written by the late-1970s UNIX crowd here at U of T. (Rob Pike, Tom Duff, David Tilbrook, and Hugh Redelmeier, I think.) qed is something of a kitchen sink, full of clumsy programmability features that I never use. The things that keep me using it are: -- Multiple buffers, each possibly associated with a different file or just anonymous -- The ability to copy or move text (the traditional t and m commands) between buffers as well as within one -- The ability to send part or all of a buffer to a shell command, to read data in from a shell command, or to send data out and replace it with that from the shell command: >mail user ... <ps -ef |tr a-z A-Z I use the last quite often; it makes qed sort of a workbench for manipulating and mining text. One can do the same with the shell and temporary files, but using an editor buffer is much handier. sam has similar abilities (but without all the needless programmability). Were sam less clumsy to use in its non-graphical mode, I'd probably have abandoned qed for sam. Norman Wilson Toronto ON (for real now)

7 years, 7 months

Re: [TUHS] basic tools / Universal Unix

by jnc＠mercury.lcs.mit.edu

> From: Ralph Corderoy > Then the real definition, ending in an execution of the empty `q'. > qq/4$^Ma2^[@qq Gah. That reminds me of nothing so much as TECO (may it long Rest in Peace). Noel

7 years, 7 months

Re: [TUHS] Happy birthday, Morris Worm!

by Doug McIlroy

> let's not forget that amazing vi-trainer called rogue. Also amazing is its robust survival at angband.org.

7 years, 7 months

Re: [TUHS] TECO was: Re: basic tools / Universal Unix

by Doug McIlroy

>Speaking of which, am I the only one annoyed by Penguin/OS' silly coloured "ls" output? Syntax coloring, of which IDE's seem to be enamored, always looks to me like a ransom note. For folks who like colorized text, Writers Workbench had a tool that can be harnessed to do a bang-up job of syntax colorizing for English: "parts" did a remarkable job of inferring parts of spechc in running text. Doug

7 years, 7 months

A Human 'Make' Program (almost)

by Forrest, Jon

I started with V6 Unix at UC Santa Barbara in 1977. I remember that when V7 came out, I learned about the 'make' program and started using it with great success to help me build a large Fortran package for signal processing. For its size, there was a lot going on in Santa Barbara at that time. It was one of the first 4 Arpanet nodes, and there were a bunch of companies making networking products and doing speech research as a result. I was a student at UC Santa Barbara but I started toying with the idea of finding a real job, mostly to make more money. I found several possibilities and went to interview at one. This place had an a need for somebody to, in essence, be a human 'make' program. The computer they used, some kind of Data General, was so slow that they couldn't do a build more that once or twice a day. So, in an attempt to speed up the build, they wanted to hire somebody who would, by hand, keep track of the last modification date of all the components in the package they sold, and do a build that only performed the necessary steps to generate the package - in other words a human make program. Apparently they figured that this would save enough time to justify the $24K salary they were willing to pay. $24K in 1978 wasn't a bad salary at all. I didn't take the job, but I've often thought that what I should have done would have been to take the job under the condition that I could mostly work remotely. Then, I could have used the 'make' program on our V7 Unix system to generate the optimal script to build the package, and then taken the script back to the company to run on the Data General computer. I figure this would have taken maybe an hour a day. The rest of the time I could have spent on the beach thinking about ways to spend that $24K. Jon Forrest

7 years, 7 months

Happy birthday, Morris Worm!

by Dave Horsfall

The infamous Morris Worm was released in 1988; making use of known vulnerabilities in Sendmail/finger/RSH (and weak passwords), it took out a metric shitload of SUN-3s and 4BSD Vaxen (the author claimed that it was accidental, but the idiot hadn't tested it on an isolated network first). A temporary "condom" was discovered by Rich Kulawiec with "mkdir /tmp/sh". -- Dave Horsfall DTM (VK2KFU) "Those who don't understand security will suffer."

7 years, 7 months

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TUHS