TUHS

tuhs@tuhs.org

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6532 discussions

by Jason Stevens

I found this project online recently. For those who love K&R and the 64 bit world. https://github.com/gnuless/ncc It outputs to a custom a.out format so it's not immediately usable. It's a dual clause BSD license too!

6 years, 6 months

Upgrading from 11/40 to 11/45 in Unix v6

by Will Senn

Dear Unix Enthusiasts, We are seriously considering upgrading our PDP 11/40 clone (SIMH), to a PDP 11/45 (preferably another SIMH) for our Unix v6 installation. Our CEO was traveling and met a techie in first class (seriously, first class?) who told him that we needed one. I thought I had better ask some folks who have gone before about it before we jumped on the bandwagon. By way of background, Our install is pretty small with a few rk’s and 256K of ram along with a few standard peripherals, and some stuff our oldtimers refuse to part with (papertape, card punch, etc). It has fairly low utilization - a developer logs in and writes code every few days and the oldtimers hunt the wumpus and play this weird Brit game about cows. It could be considered a casual development and test environment and an occasional gaming console. Here is what I would like to know that I think y’all might be particularly equipped to answer: 1. Are there any v6 specific concerns about upgrading? 2. Why should we consider taking the leap to the 11/45? Everything seems to work fine now. 3. If we jump in and do the upgrade, how can we immediately recognize what has changed in the environment? I.e what are some things that we can now do that we couldn’t do before? 4. If we just insert our current diskpacks into the new system, will it just boot and work? Or what do we need to before/after booting to prepare/respond to the new system? 5. Is 256K enough memory or what configuration do y’all recommend? 6. Is there anything else we need to know about? Regards, Will Sent from my iPhone

6 years, 6 months

Re: [TUHS] building world using sh run in /usr/source in v6

by jnc＠mercury.lcs.mit.edu

> From: Larry McVoy > And cron is really 3246 bytes? And 2054 for init? Don't those seem too > small? Linux's cron is 44472 and that's with shared libs No, 3246 is the same as mine, and my init (which has a few changes from stock) is 2064. I'm not surprised the later one is 44KB - that's in part due to the denseness of PDP-11 binary (and the word-size is only 16 bits), but more broadly, I expect that it goes to my complaint about later Unixes - they've lost, IMO, the single most important thing about the PDP-11 Unixes, which is their bang/buck ratio. Noel

6 years, 6 months

Almost forgot: In Memoriam: Grace Hopper

by Dave Horsfall

We lost Rear Admiral "Amazing" Grace Hopper on this day in 1992; amongst other things she gave us COBOL and ADA, and was allegedly responsible for the term "debugging" when she removed a moth from a relay on the Harvard Mk I. -- Dave

6 years, 6 months

Re: [TUHS] Upgrading from 11/40 to 11/45 in Unix v6

by jnc＠mercury.lcs.mit.edu

> From: Will Senn > We are seriously considering upgrading our PDP 11/40 clone (SIMH), to a > PDP 11/45 (preferably another SIMH) Heh! When I saw the subject line, I thought you wanted to upgrade a _physical_ -11/40 to an -11/45. ('Step 1. Sell the -11/40. Step 2. Buy an -11/45.' :-) > for our Unix v6 installation. Why on earth would an organization have such a thing? :-) > Our CEO was traveling and met a techie in first class (seriously, > first class?) who told him that we needed one. Heh. If said techie knows about the two, he's probably pretty senior (i.e. eligible for Social Security :-), and thus elegible for first class... :-) > It has fairly low utilization - a developer logs in and writes code > every few days Who the *&%^&*(%& is still writing code under V6?! And how do you all get the bits in and out? (I run mine under Ersatz-11, which has this nice device which allows it to read files off the host file system; transfering stuff back and forth is a snap, I do all my editing with Epsilon on my Windoze box, 'cause I'm too lazy to bring up the V6 Emacs I have.) > 1. Are there any v6 specific concerns about upgrading? Not that I know of. > 2. Why should we consider taking the leap to the 11/45? Everything > seems to work fine now. You're asking _us_? Some larger applications will only run on an split-I-D machine, is about the only reason I can think of. Oh, also, the floating point instructions on the /45 are the only kind understood by V6; the C compiler doesn't emit the ones the /40 provides. Any floating point code run on the /40, the instructions are simulated by a trap handler (by way of the OS, which has to handle it and reflect it to the user process). I.e. very slow. > 3. If we jump in and do the upgrade, how can we immediately recognize > what has changed in the environment? I.e what are some things that we > can now do that we couldn't do before? See above. > 4. If we just insert our current diskpacks into the new system, will it > just boot and work? Or what do we need to before/after booting to > prepare/respond to the new system? Any V6 disk pack can be read/mounted on any V6 machine. Any binaries (the OS, or user commands) for the -11/40 will run on the -/45. (Which is why the V6 dist includes binaries for /40 versions of the OS only.) To make use of the /45, you need a different copy of the OS binary, built from a slightly different set of modules. (Replace m40.s with m45.s; and you will need to re-asssemble l.s, prepending it with data.s.) Both variants can live on the same pack, under different filenames; select the right one at boot time. > 5. Is 256K enough memory or what configuration do y'all recommend? 256KB is all you can have. Neither SIMH nor Ersatz-11 support the Able ENABLE: http://gunkies.org/wiki/Able_ENABLE which is what you need to have more than 256KB on a UNIBUS -11. > From: Clem Cole > You'll probably want to configure a kernel for the 45 class machine. > Look at the differences in the *.s files in the kernel. More importantly, look at the 'run' file in /usr/sys, which has commented out lines to build the OS image for /45-/70 class machines. > But either way you should configure the system to use the largest drive > v6 has. This is actually of limited utility, since a V6 file system is restricted to 65K blocks _max_. So a disk with 350K blocks (like an RP06), you'll have to split it into like 5 partitions to use it all. > From: Will Senn > Do you know of some commonly used at the time v6 programs that needed > that much space? Heh. Spun up my v6, and did "file * | grep separate" in /bin and /usr/bin, and then recalled that V6 was distributed in a form suitable for a /40. So, null set. Did the same thing on /bin from the MIT V6+ system, and got: a68: separate I&D executable not stripped a86: separate I&D executable not stripped bteco: separate I&D executable not stripped c86: separate I&D executable not stripped e: separate I&D executable not stripped emacs: separate I&D executable not stripped lisp: separate I&D executable not stripped mail: separate I&D executable not stripped ndd: separate I&D executable not stripped s: separate I&D executable not stripped send: separate I&D executable not stripped teco: separate I&D executable not stripped No idea what the difference is between 'teco' and 'bteco', what 's/send' do, etc. > Is there any material difference between doing it at install time vs > having run on 11/40 for a while and moving the disk over to the 11/45 > later? No; like I said, you can have two different OS binaries on the disk, and select which one you boot. > On a related note, how difficult is it to copy the system from rk to > hp? I know I can rebuild, but I'm sure there's a quicker/easier method... Build a system with both, and then copy the files? I'd use 'tar' (I have a V6 tar, but it uses a modified OS with the smdate() call added back in) to do the moving (which would retain the last-write dates); 'tp' or 'stp' would also work. The hack _I_ used on simulated systems was to expand the file that held the 'disk pack', mount it as a different kind of pack (RL or RP), and then go in and hand-patch the disk size in the root block with 'db', then 'icheck -s' to re-build the free list. Note: this won't give you more inodes, so you may run out, but the usual inode allocation is pretty generous. Noel PS: Speaking of the last write dates, I have versions of mv/mvall, cp/cpall, ln, chmod etc which retain them (using smdate()). If there's an actual community of people using V6, I should upload all the stuff I have. Although it might be good to establish some central location for exchange of V6 code. However, I don't and won't (don't even ask) use GitHub or any similar modern thing.

6 years, 6 months

building world using sh run in /usr/source in v6

by Will Senn

The setting up document hints at how to build world so to speak in v6. However, when I log in as bin (most files are owned by bin) and: chdir /usr/source sh run I get a number of failed items along these lines: cp a.out /etc/cron Can't create new file. cp a.out /etc/init Can't create new file. A little digging around points to the problem - some files are owned by daemon, others by root: -rwsrwsr-- 1 daemon 3246 Oct 10 12:54 cron -rwxrwxr-- 1 root 2054 May 13 23:50 init My question is this, is the system recompiled en-masse using the run script in /usr/source or not? It certainly appears to be the method, as it contains a bunch of chdir somedir; time sh run lines including the /usr/sys/run file... If it's not, what was the method? I gather I can force it by logging in as root and running those sections of the run script pertaining to files owned by root, and the same for daemon, but that seems inefficient and begs the question why didn't they have run scripts for root and daemon that were separate from the ones for bin. Thanks, Will -- GPG Fingerprint: 68F4 B3BD 1730 555A 4462 7D45 3EAA 5B6D A982 BAAF

6 years, 6 months

Re: [TUHS] Upgrading from 11/40 to 11/45 in Unix v6

by jnc＠mercury.lcs.mit.edu

> From: Paul Winalski > What is magic number 0411? That one I've never heard of before. It's a PDP-11-ism. Separate I+D. Noel

6 years, 6 months

Re: [TUHS] Deleted lib1 and lib2 in v6, recoverable?

by jnc＠mercury.lcs.mit.edu

> From: Will Senn > I whacked /usr/sys/lib1 and lib2 'accidentally' meaning I logged in as > bin changed to /usr/sys and typed rm lib1 and rm lib2 :). Doesn't sound very accidental... :-) > sh run as bin doesn't do it. Odd. 'run' in /usr/sys on my V6 machine (not that I use that, mind) says: chdir ken cc -c -O *.c ar r ../lib1 rm *.o chdir ../dmr cc -c -O *.c ar r ../lib2 rm *.o which should regenerate them - sort of. I suspect you really meant 'doing sh run creates a lib1 and lib2, but then I get errors from the ld phase with missing symbols'. Yes? If so, the thing is that the V6 linker won't pull in an object module from a library unless a global in it satisfies an already existing (i.e. in the linking process) undefined global. (I don't know if this is true of later linkers; never used 'em.) In other words, when loading a multi-module system, the module with 'main' has to be first, and then the rest in an order such that each one holds a previously-undefined symbol. So the order of the object modules you'll get in lib? from the above, if you precede them with 'rm lib?', is probably not the right order. (The above shell script assumes they already exist, with the modules in the right order, so the above just replaces them with the newly compiled versions...) > So, what magic incantation is required to rebuild them. Here's the ordering in lib1: main.o alloc.o iget.o prf.o rdwri.o slp.o subr.o text.o trap.o sig.o sysent.o clock.o fio.o malloc.o nami.o pipe.o sys1.o sys2.o sys3.o sys4.o Other orders would work too (e.g. you could move sys?.o up just after sysent.o and it should work). My lib2 is somewhat odd, so I hesitate to list it, but since most modules in dmr are pulled in from entries in c.c, almost any order will work, I think. Noel

6 years, 6 months

Re: [TUHS] Upgrading from 11/40 to 11/45 in Unix v6

by jnc＠mercury.lcs.mit.edu

> From: Will Senn > Thanks for not dismissing the thread as frivolity. Hey, anyone wanting to do things with V6 I take seriously! :-) > I'm sure y'all have seen Mills's winning Best in Show IOCCC entry: > https://www.ioccc.org/2018/mills/hint.html Yes, that was pretty awesome. > Fantastic, I'm prolly gonna try it. OK; if you want to know what it's doing (somehow I figured you probably didn't just want to simply follow the instructions :-) that is different from the /40 (it's quite different, and somewhat complicated), I just wrote this: http://gunkies.org/wiki/Unix_V6_kernel_memory_layout to explain it a bit. Currently, one has to read the source to 'sysfix', and also m45.s, to understand how the /45 version works; that new page is a little crude still, but it hopefully explains the big picture. > If the instructions in Setting up are as good for the 45 as they are for > the 40, I should be able to bring one up relatively painlessly. I just took a look at "Setting up UNIX - Sixth Edition", and it doesn't really say much about the /45; it basically just says 'the /45 is wiered inside' and 'look at sys/run'. It is certainly true that that does cover all one needs to bring V6 up on the /45, but... The coverage of what to do if your '45' has hardware floating point is pretty complete, though. > What it sounds like is that Unix was transitioning from non-I/D land to > I/D land and maintaining a measure of backward compatibility That's pretty accurate. One main advantage of the /45 is that it could have a lot more disk buffers, but I'm not sure that makes much difference for emulation. If you have some application that won't fit well in 64KB, that's big, but that's a user-land difference, not the OS. > Is there a bootable tape of the MIT system extant? Not yet, sorry. I do have a complete dump, but it i) includes all the users' personal files, and ii) is not well organized. It's on my to-do list. Noel

6 years, 6 months

Re: [TUHS] Deleted lib1 and lib2 in v6, recoverable?

by Doug McIlroy

> But wasn't it tsort that did the heavy lifting to get things in order? An amusing notion. Having written tsort, I can assure you it couldn't lift anything heavy--it used the most naive quadratic algorithm. But it was good enough for libc. Doug

6 years, 6 months

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TUHS