TUHS

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6541 discussions

by Warren Toomey

All, I asked Peter Salus if there is an electronic version of his great book "A Quarter Century of Unix". There isn't one, so I scanned my book in. Peter has given TUHS the right to distribute the scanned version. I've just added a link to the PDF of the scan here: http://wiki.tuhs.org/doku.php?id=publications:quarter_century_of_unix But, if you can, buy the paper version as well! Many thanks to Peter for his generosity. Cheers, Warren

9 years, 6 months

Missing pages in Berkeley_Unix_History.pdf

by markus schnalke

Hoi. Yesterday, I came across the file Berkeley_Unix_History.pdf on my disk. It contains scanned articles of UNIX Review January 1985, October 1985 and January 1986. Searching the web brought up this online location for the file: http://simson.net/ref/free_software/Berkeley_Unix_History.pdf I read the articles for the first time and had a great time doing so. Especially the ``Berkeley Underground'' article was pure fun! Here, have some impression: We modified the kernel to support asynchronous I/O, distri- buted files, security traces, "real- time" interrupts for subprocess multitasking, limited screen editing, and various new system calls. We wrote compilers, ass- emblers, linkers, disassemblers, database utilities, cryptographic utilities, tutorial help systems, games, and screen-oriented ver- sions of standard utilities. User friendly utilities for new users that avoided accidental file deletion, libraries to support common operations on data structures such as lists, strings, trees, sym- bol tables, and libraries to perform arbitrary precision arithmetic and symbolic mathematics were other contributions. We suggested im- provements to many system calls and to most utilities. We offered to fix the option flags so that the dif- ferent utilities were consistent with one another. To Us, nothing was sacred, and We saw a great deal in UNIX that could stand improvement. Much of what We implemented, or asked to be allowed to implement, is now a part of System V and 4.2 BSD; others of our innovations are still missing from all versions of UNIX. Despite these accom- plishments, it seemed that whenever We asked The Powers That Be to install Our software and make it available to the rest of the system's users, We were greeted with stony silence. Unfortunately, the scan is not complete as some pages are missing. For example, page 43 (the title page of the mentioned article) is among them. Does anyone know where to get the full articles? meillo

9 years, 6 months

Re: [TUHS] etymology of cron

by jnc＠mercury.lcs.mit.edu

> From: Ronald Natalie > a new GADS (Gateway Architecture and Data Structures) under Dave > Mills's leadership would form which I attended until they morphed it > into the IETF To give a bit more detail, GADS was not producing needed stuff as fast as was needed, so it was split into InArc and InEng, with Dave running InArc and Corrigan (initially, Gross later) in charge. Noel

9 years, 6 months

Re: [TUHS] etymology of cron

by David

It has been updated again: The origin of the name cron is from the Greek word for time, χρόνος (chronos).[2][3] (Ken Thompson, author of cron, has confirmed this in a private communication with Brian Kernighan.) So it would appear that if enough people bang on enough keyboards on the Wikipedia site, things can change. David

9 years, 6 months

More wiki work: free Unix licenses

by Warren Toomey

All, although I can't contribute to the actual history of Unix, I can at least document what happened "afterwards". Here's a piece about the journey to make free Unix source code licenses available: http://wiki.tuhs.org/doku.php?id=events:free_licenses Comments welcome. Cheers, Warren

9 years, 6 months

Re: [TUHS] PDP-11 MARK (was: Early Unix function calls: expensive?)

by Johnny Billquist

On 2016-01-06 01:54, Dave Horsfall <dave(a)horsfall.org> wrote: > On Mon, 4 Jan 2016, Ronald Natalie wrote: >> >Just never figured out how to make good use of the MARK instruction on >> >the PDP-11. > RSX-11 probably used it, though, as could've RSTS... Nope. Nothing in RSX uses it. As others said, probably nothing anywhere used it. And, as I pointed out, if you use MARK, then you cannot really use split I/D-space, since the stack (data) needs to be in instruction space. Johnny -- Johnny Billquist || "I'm on a bus || on a psychedelic trip email: bqt(a)softjar.se || Reading murder books pdp is alive! || tryin' to stay hip" - B. Idol

9 years, 6 months

Re: [TUHS] PDP-11 MARK (was: Early Unix function calls: expensive?)

by Johnny Billquist

On 2016-01-05 18:43, Ronald Natalie<ron(a)ronnatalie.com> wrote: > > Just never figured out how to make good use of the MARK instruction on the PDP-11. Not surprising. As others noted, few ever did. And apparently none responding actually do either. It *is* a stupid instruction in many ways. And it's not for multiple returns either. It's an odd way of handling stack cleanup without a frame pointer. It's extremely bad, since it actually requires the stack to be in instruction space. And yes, you are expected to execute on the stack. The idea is that the caller pushes arguments on the stack, but the cleanup of the stack is implicitly done in the subroutine itself, and at the same time you get an argument pointer. Example: Calling: MOV R5,-(SP) ; Save old R5 MOV <argn>,-(SP) MOV <argn-1>,-(SP) . MOV <arg1>,-(SP) MOV #MARKN,-(SP) ; Where the N in MARK N is the number of arguments you just pushed. MOV SP,R5 JSR PC,SUB . . In the subroutine you then have the arguments available relative to R5. So that arg1 is available at 2(R5) for example. SUB: . . . RTS R5 There is a lot going on at this point. The trick is to note that the code does an RTS R5 to return. If people remember what happens at that point, PC gets loaded with R5, while R5 gets loaded with the PC that we actually would like to return to (since that's what is at the top of the stack). And R5 is pointing into the stack, at the MARK instruction, so execution continues with actually performing the MARK. MARK, in turn, will case SP <- PC + 2*N, thus restoring the stack pointer to point to the place where the original R5 was stored. Next, it does a PC <- R5, so that we now have the PC point to where we actually want to return. Next it does a R5 <- (SP)+, meaning we actually restored the original R5. And so we have cleaned up the stack, preserved R5, and returned to the caller again. Also notice that the subroutine could have pushed any amount of data on the stack before the return, and I suspect the idea was that the process would not have needed to clean that up either. However, that fails, since the RTS needs the return address at the top. But you can essentially solve that by pushing -2(R5) before returning. Ugly, isn't it? :-) Johnny

9 years, 6 months

Early Unix function calls: expensive?

by Warren Toomey

I just re-found a quote about Unix processes that I'd "lost". It's by Steve Johnson: Dennis Ritchie encouraged modularity by telling all and sundry that function calls were really, really cheap in C. Everybody started writing small functions and modularizing. Years later we found out that function calls were still expensive on the PDP-11, and VAX code was often spending 50% of its time in the CALLS instruction. Dennis had lied to us! But it was too late; we were all hooked... http://www.catb.org/esr/writings/taoup/html/modularitychapter.html Steve, can you recollect when you said this, was it just a quote for Eric's book or did it come from elsewhere? Does anybodu have a measure of the expense of function calls under Unix on either platform? Cheers, Warren

9 years, 6 months

Re: [TUHS] TUHS Digest, Vol 2, Issue 5

by David

The comments in the rp06 walking across the floor reminds me of a time when I was installing netnews at a very new company and as the data transferred from the tape (we didn’t have a modem yet, that was to happen in a week or so) to the disk the disk got into a walking state. I was standing with my foot against the front of the drive to keep it from moving when a friend walked into the machine room and asked what I was doing. I said ‘keeping it all together’ and he asked about my foot. I moved it, the disk walked out a small amount and I replace my foot. He laughed and walked away. About 15 or 20 minutes later it was all back to ‘normal’ and I never had another problem with it. David > On Jan 2, 2016, at 1:31 PM, tuhs-request(a)minnie.tuhs.org wrote: > > several > RP06 (200MB) removable disks (for a picture and description, see > > http://www.columbia.edu/cu/computinghistory/rp06.html

9 years, 6 months

Re: [TUHS] Early Unix function calls: expensive?

by norman＠oclsc.org

As late as 1990, every UNIX I knew of still used the expensive calls/ret instructions for subroutine calls. I vaguely remember a consensus (and I certainly shared the feeling) that in hindsight it would have been better to use jsb/rsb, but changing everything would have been so much work that nobody wanted to do it. 1990 was already past peak VAX in the UNIX world, so I can't imagine anyone bothering to make such a change to an existing system after then. Especially a system that already had many existing installations who would have to deal with the resulting compatibility problem. During the latter part of the 1990s, I was actively supporting a private UNIX system just for myself on a few MicroVAXes at home. One of the things I did was to write a VAX code generator for the then-current version of lcc (the one around which the book was written), so as to have an ISO-compatible compiler and convert all of /usr/src (not so big even in those days) to ISO. It was an interesting exercise and I learned a lot, but even then, I wasn't brave enough to adopt an incompatible subroutine-calling convention. Another big time waste in the original VAX UNIX was the system-call interface: arguments were left on the stack (where they had been put before calling the syscall stub routine in libc); the kernel then had to do a full-fledged copyin to get them. It occurred to me more than once to change the convention and have the syscall stubs copy the arguments into registers before executing the chmk (syscall) instruction. That instruction didn't touch the registers; the kernel saved them early in the chmk trap routine, in its own address space, so no copying or access checking would have been required to fetch their call-time contents. That would still have been a messy change to make, because I'd have to be sure every program had been relinked with the new-style libc before changing the kernel. (This was a system without shared libraries.) But on a personal system it would have been doable. I never did. It's possible that current UNIX-descended/cloned systems that have VAX ports, like Linux or Open/Free/NetBSD, have had a chance to start over and do better on subroutine calls and system calls. Does anyone know? Norman Wilson Toronto ON

9 years, 6 months

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