TUHS December 2018

tuhs@tuhs.org

52 participants
58 discussions

Re: [TUHS] 2.9bsd with networking on 18-bit possible?

by jnc＠mercury.lcs.mit.edu

> From: Paul Ruizendaal > project to make V6 run with the Gurwitz TCP stack on a TI990 clone > (which is pretty similar to a PDP11). Neat! > the code size is about 25KB for both a minimal V6 kernel and the TCP > stack, the rest is data. That's impressively small; the MIT V6+ with 'demux only in the kernel' was 40KB for the combined code (although I can't easily get separate figures for the networking part and the rest). > The Gurwitz code also has an Ethernet driver (note ARP was not invented > yet) How did it get Ethernet addresses? Noel

6 years, 3 months

2.9bsd with networking on 18-bit possible?

by Paul Ruizendaal

> I'm sure it's been attempted before, but would anyone be up to the > challenge of trying to get that going with networking on an > 18-bit-address-space pdp11? By coincidence I’m in the middle of a project to make V6 run with the Gurwitz TCP stack on a TI990 clone (which is pretty similar to a PDP11). It runs without separate I/D as two processes in about 100KB. The Gurwitz TCP stack was the reference implementation for the VAX that BBN did in 1981. It is in the THUS archive: https://minnie.tuhs.org//cgi-bin/utree.pl?file=BBN-Vax-TCP As documented in IEN168, the actual TCP processing happens in a separate kernel process, much like process 0 (swapper) in Unix itself. It turns out that the network process shares no data (other than the u struct) with the kernel proper and can be run in a separate address space. Just a few ’thunks’ are needed: open/read/write/close from the kernel to the TCP stack and sleep/wakeup in the other direction. A V6 Unix kernel runs in 48KB with buffers, the TCP stack with buffers needs about the same; both must remain resident - i.e. it ties up about 100KB of the 256KB core on a 18-bit machine. I suppose when using separate I/D it can run without thunks: the code size is about 25KB for both a minimal V6 kernel and the TCP stack, the rest is data. In my setup, network connectivity is via a SLIP interface. The Gurwitz code also has an Ethernet driver (note ARP was not invented yet), but I’m not using that. I’m happy to report that this 1981 tcp/ip code can still talk to current OSX and Linux machines. Just yesterday I got the setup working and I can run minimalist telnet connections etc. Alas it is not quite stable yet, it tends to crash after 5-10 minutes of use. The BBN reference implementation includes FTP and Telnet servers and clients which I think will still interoperate with current versions. As a final remark note that this BBN code uses an API that is almost unchanged from the API as used on NCP Unix. As compared to sockets this means that a listening connection is not a rendez-vous, but blocks until a connection is made (and then becomes an active connection, i.e. stops listening), and that there is no “select” type functionality.

6 years, 3 months

Re: [TUHS] 2.9bsd with networking on 18-bit possible?

by jnc＠mercury.lcs.mit.edu

> From: Clem Cole > I could be mis remembering No... :-) > IIRC the original PTY driver goes back to the Rand and/or UofI for the > NCP. Yup. I found a pty.c in the NCP system, it's clearly the ancestor (comments match): https://minnie.tuhs.org//cgi-bin/utree.pl?file=SRI-NOSC/dmr/pty.c > I suspect BBN got it from the Bruce Borden's Rand distribution tape Or possibly indirectly; my copy of the NCP came from NOSC via SRI. In addition to the one above, there are also these: https://minnie.tuhs.org//cgi-bin/utree.pl?file=SRI-NOSC/dmr/misc/pty.c.ill https://minnie.tuhs.org//cgi-bin/utree.pl?file=SRI-NOSC/dmr/misc/pty.c.x Here: https://minnie.tuhs.org//cgi-bin/utree.pl?file=BBN-V6/dmr/pty.c is the BBN version, you can compare the them all. The MIT one is derived from the BBN one. > Named Piped were definiately a Rand-ism (they were originally called 'Rand Pipes') Well, _RAND_ called them 'ports': https://minnie.tuhs.org//cgi-bin/utree.pl?file=BBN-V6/doc/ipc/ports > But there were issues and somethings were not 100% until the UofI NCP; > which was the first really complete NCP for UNIX. Somewhere I found a document about the UofI code, I think they wrote it from scratch? Sorry, too lazy to look at it. See here: https://minnie.tuhs.org//cgi-bin/utree.pl?file=SRI-NOSC for links. Noel

6 years, 3 months

Re: [TUHS] 2.9bsd with networking on 18-bit possible?

by jnc＠mercury.lcs.mit.edu

PS: > IIRC, outbound packets are copied into kernel buffers IDRC; according to the documentation, outbound packets are DMA'd directly from user memory. I have yet to read the code to verify this. > we must have added PTY's of some sort There is indeed a PTY driver; it has comments from BBN'ers who edited it, so perhaps we got it from BBN. > I don't remember which one SMTP used. The 'simple' TCP. > The whole thing worked _really_ well. Alas, I don't think anyone else > picked up on it. So I found a long list of people we sent tapes to. Oh well.... > The kernel code is not that large, it should even run on a /40, without > overlays (although the number of disk buffers would probably get hit). Well, maybe... Here is the output of 'size' on the last Unix image for that machine: 40560+3098+44594 It was a /45, so split I/D (no overlays, though). How much could be trimmed out of that, I'm not sure. Noel

6 years, 3 months

2.9bsd with networking on 18-bit possible?

by Jacob Ritorto

Hi, I have an 11/45 I'm hoping will be running soon. I'd like to run 2.9BSD on it because it's the most highly functional system I know of that has "official hopes" to fit on such a restrictive machine. I've heard that it's really unlikely / tough to get a kernel built that'll run tcp (I care mostly about ftp and telnet) on such a small-memory-footprint machine. Is this true? Would anyone be willing to do a quick mentoring / working session with me to get me up to speed with the constraints I'm facing here and possibly give me a jump on making adjustments to build such a kernel if possible? thx jake P.S. There's kind of an implied challenge in the 2.11bsd setup docs, mentioning that "2.11BSD would probably only require a moderate amount of squeezing to fit on machines with less memory, but it would also be very unhappy about the prospect." I'm sure it's been attempted before, but would anyone be up to the challenge of trying to get that going with networking on an 18-bit-address-space pdp11?

6 years, 3 months

Re: [TUHS] 2.9bsd with networking on 18-bit possible?

by jnc＠mercury.lcs.mit.edu

> From: Clem Cole <clemc(a)ccc.com> > This is why I suggested that if you really want telnet and ftp to the > PDP-11, you might be better off moving the networking stack out of the > kernel Really, the answer is that I need to get off my @ss and put the MIT V6+ system up (I have all the files, just need to get a round tuit). It has TCP/IP, but is it not all crammed into the kernel. And unlike the early BBN V6, it doesn't do TCP as a single process to which all the other client/server processes talk via IPC. Instead, the only thing in the kernel is inbound demuxing, and minimal outbound processing. (IIRC, outbound packets are copied into kernel buffers; an earlier version of the networking interface driver actually did do inbound and outbound DMA directly from buffers in the user's process, but only one process could use the network interface at a time.) The TCP code was a library that was built into the user process which did the server/client applications. (The servers which supported login, like FTP, needed to run as root, like the ordinary login, setuid'ing to the entered user-id.) I don't remember if we supported server Telnet, but I think we did. So we must have added PTY's of some sort, I'll have to check. Since the TCP was in the user process, we actually had a couple of different ones, depending on the application. Dave Clark had done a quick-n-dirty TCP on the Alto (in BCPL) which was only good for things like user Telnet, not for applications that sent a lot of data. We ported that one for the first TCP; we later did a 'high-speed bulk data' TCP, used for FTP, etc. I don't remember which one SMTP used. The whole thing worked _really_ well. Alas, I don't think anyone else picked up on it. The kernel code is not that large, it should even run on a /40, without overlays (although the number of disk buffers would probably get hit). And since the TCP is in user processes, it could all get swapped out, so it would run OK on machines without that much physical memory. The issue is going to be that it will need a new network interface driver, since I think the only driver ever done for it was for Pronet. And now we get back to the 'what interfaces are available' question. Doing a DEC driver would allow use of DEQNA's and DELQA's on QBUS machines, which would be optimal, since they are common. And people could bring up Unix with TCP/IP on -11/23's. But we'd have to add ARP (which I would do as a process, with only the IP->Ether address mapping table stored in the kernel). I wrote a really nice ARP for the C Gateway that could easily be used for that. Noel

6 years, 3 months

Re: [TUHS] 2.9bsd with networking on 18-bit possible?

by jnc＠mercury.lcs.mit.edu

> From: Warner Losh > I kinda doubt it has good NCP support: it was released in November of > 1983. Wow, that far back? I'd assumed it was later (considerably later). Looking at the 2.9 networking stuff: https://minnie.tuhs.org//cgi-bin/utree.pl?file=2.9BSD/usr/net/sys/net it does indeed have _no_ NCP support. > I'd get it running in simh, then move to real hardware. Absolutely; running in an emulator is, I have found, a key step on getting an old OS running. I've found Ersatz-11 to be really good for PDP-11 emulation. > It's going to take a lot of elbow grease to make that work, I think. Indeed; part of the problem, if the goal is going to be 'run it on real hardware' is 'what network interface to use'. All the ARPANET interfaces are out. There are drivers there for Proteon, Ungermann-Bass, Xerox 3MB Ethernet, etc interfaces, but i) where you gonna find one, and ii) you'll need a router to connect up to most other things. There's a driver for the Interlan Ethernet interface, but AFAIK, those are non-existent. (If anyone has one they're willing to part with, please let me know!) DEC Ethernet interfaces are available, but i) only the QBUS ones are common, DEUNAs and DELUAs are almost impossible to find, that I've even seen, and ii) it would need a driver. > Ultrix-11 is of similar vintage, and similar functionality and does boot > on the 18-bit 11's. Yes, definitely worth looking at; I know it had TCP/IP (we had it on our -11/73 at Proteon), but I don't know which interfaces it supported; probably just the DEC ones (which, given the above, is not necessarily a Bad Thing). Noel

6 years, 3 months

Re: [TUHS] 2.9bsd with networking on 18-bit possible?

by jnc＠mercury.lcs.mit.edu

> From: Grant Taylor > What protocols did 2.9BSD support? Did it have NCP? NCP was turned off on 1 January, 1983. What do you think?a > Would it be any easier to use an external NCP to TCP/IP gateway? Such as? Noel

6 years, 3 months

Happy birthday, Grace Hopper and J.F.Ossana!

by Dave Horsfall

Augusta Ada King-Noel, Countess of Lovelace (and daughter of Lord Byron), was born on this day in 1815; arguably the world's first computer programmer and a highly independent woman, she saw the potential in Charles Babbage's new-fangled invention. J.F.Ossanna was given unto us on this day in 1928; a prolific programmer, he not only had a hand in developing Unix but also gave us the ROFF series. Who'ld've thought that two computer greats would share the same birthday? -- Dave

6 years, 3 months

Grace Hopper

by Dave Horsfall

We gained Rear Admiral Grace Hopper on this day in 1906; known as "Amazing Grace", she was a remarkable woman, both in computers and the Navy. She coined the term "debugging" when she extracted a moth from a set of relay contacts from a computer (the Harvard Mk I) and wrote "computer debugged" in the log, taping the deceased Lepidoptera in there as well. She was convinced that computers could be programmed in an English-like language and developed Flow-Matic, which in turn became, err, COBOL... She was posthumously awarded the Presidential Medal of Freedom in 2016 by Barack Obama. -- Dave

6 years, 3 months

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TUHS December 2018