5 ms·

Best of Show: PDP-7 and PDP-11/40 emulation

157 points by wscott 8y ago

wscott 8y ago
Here is the C program: https://www.ioccc.org/2018/mills/prog.c https://www.ioccc.org/2018/mills/prog.c It is a PDP-7 emulator that can boot the most ancient known snapshot of Unix. This is running Unix from 1969 where the compiler is 'bc' (no 'cc' yet) then, he wrote a PDP-11 emulator in PDP-7 assembly and uses the PDP-7 to emulate a PDP-11 to boot BSD 2.9.
- wscott 8y ago
  For context, this is from The International Obfuscated C Code Contest https://www.ioccc.org/ https://www.ioccc.org/
  - szc 8y ago
    Also, the 26th IOCCC has now started, if you are inspired! [ Submitted as news: https://news.ycombinator.com/item?id=18764925 https://news.ycombinator.com/item?id=18764925 ]
- spacenick88 8y ago
  Hmm, seems neither current gcc nor clang can compile this even with -ansi or -std=c89
  - racingmars 8y ago
    The submission has a Makefile that works fine for me. It needs several things defined by -D for configuration options for the emulator. https://www.ioccc.org/2018/mills/ https://www.ioccc.org/2018/mills/
    - spacenick88 8y ago
      Ahh thanks!
    - anthk 8y ago
      In my case it exits the shell upon loading ./v6. I compiled it with gcc 4.2 under OpenBSD 6.4. In happens the same with clang6.
      - szc 8y ago
        IOCCC Judge here: If you are using an xterm, you might try using "xterm -hold". It seems that the termios structure is getting (re)set with some invalid values and some systems (one report from NetBSD) cause the terminal / shell to abort. We are figuring out how to do an update to fix this issue.
- flyinghamster 8y ago
  I laughed out loud when I got to the part about the PDP-11 emulation being written to run on the emulated PDP-7. That cranks up the hack value to 11.
  - dboreham 8y ago
    The Turducken of software.
    - WorldMaker 8y ago
      It's not a true turducken until someone takes the author up on their suggestion to in turn emulate a VAX 780 on top the PDP-11/40 here.
      - dboreham 8y ago
        Turduckens+ all the way down... +A recursively structured arrangement of Turing Machines.
jsolson 8y ago
This is amazing. Make sure to view it on a sufficiently wide browser to see the ASCII art of a torn piece of punched paper tape.
- wscott 8y ago
  The program would be impressive if it was clearly written and commented.
  - bitofhope 8y ago
    The contest is about obfuscated C. Clearly written or not, I'm impressed.
  - deleted 8y ago
    [deleted]
- a1369209993 8y ago
  The binary on the paper tape seems to be ascii (with a parity bit) reading "pdp-7emu.s".
jhallenworld 8y ago
We are in the strange situation with these emulators that all code ever written can be executed today, no problem. Have some Fortran-II code for the IBM 1401? No problem. Want to run some Analytical Engine code (a machine that couldn't even be constructed)? No problem: https://www.fourmilab.ch/babbage/emulator.html https://www.fourmilab.ch/babbage/emulator.html Can you really say that this early code is obsolete? I think not, it's just different.
- dboreham 8y ago
  That Turing guy was on to something..
- beagle3 8y ago
  Dolphin runs Wii. Code, Xenia does XBox360 - but the future for XBoxOne emulation looks bleak.
  - robdachshund 8y ago
    Eh the new consoles use x86 pc parts. The xbone even runs a windows kernel. It would be less emulation and more just figuring out the supporting software. This is also the case with the original xbox. It's been hard to get working because it uses proprietary nvidia drivers and some weird version of windows 2000.
meatsock 8y ago
typo: "Thompson re-wrote a filesystem emulation he had been experementing with" should be experimenting
macjohnmcc 8y ago
Way back in the early 80's when I was in high school I had an off campus class where I took a course on PDP-11 assembly language. Sadly we had to run our code in a PDP-11 emulator on a DEC System 10 and it was incredibly slow but I do remember how much I liked the PDP-11 instruction set. I wish I had kept the book from the class.
- tacon 8y ago
  All the old DEC manuals are online. For example, the PDP-11/40 system manual: http://bitsavers.informatik.uni-stuttgart.de/pdf/dec/pdp11/1140/DEC-11-H40SA-A-D_PDP-11_40_System_manual.pdf http://bitsavers.informatik.uni-stuttgart.de/pdf/dec/pdp11/1...
userbinator 8y ago
The short version is we have gone so far back in the history of UNIX that we don’t have filesystem paths yet. Incidentally, the same was true of MS-DOS: no paths in version 1, only drive letters; directories and paths were introduced in version 2. However, early UNIX doesn't seem to have drive letters...
ncmncm 8y ago
This is the best thing I have read this year. I expect I will still be able to say that next month.
nickjj 8y ago
If anyone wants to mess around with a PDP-11 simulator, you can get it up and running with Docker in 1 command. Details are at: https://nickjanetakis.com/blog/run-the-first-edition-of-unix-1972-with-docker https://nickjanetakis.com/blog/run-the-first-edition-of-unix...
kristopolous 8y ago
Where do people like this exist and how can I hire them? Really...
kevinwang 8y ago
Can anyone explain the background of this for a youngin like me whose first computer was Windows XP?

157 points by wscott 8y ago

Here is the C program: https://www.ioccc.org/2018/mills/prog.c https://www.ioccc.org/2018/mills/prog.c It is a PDP-7 emulator that can boot the most ancient known snapshot of Unix. This is running Unix from 1969 where the compiler is 'bc' (no 'cc' yet) then, he wrote a PDP-11 emulator in PDP-7 assembly and uses the PDP-7 to emulate a PDP-11 to boot BSD 2.9.

wscott 8y ago
For context, this is from The International Obfuscated C Code Contest https://www.ioccc.org/ https://www.ioccc.org/
- szc 8y ago
  Also, the 26th IOCCC has now started, if you are inspired! [ Submitted as news: https://news.ycombinator.com/item?id=18764925 https://news.ycombinator.com/item?id=18764925 ]
spacenick88 8y ago
Hmm, seems neither current gcc nor clang can compile this even with -ansi or -std=c89
- racingmars 8y ago
  The submission has a Makefile that works fine for me. It needs several things defined by -D for configuration options for the emulator. https://www.ioccc.org/2018/mills/ https://www.ioccc.org/2018/mills/
  - spacenick88 8y ago
    Ahh thanks!
  - anthk 8y ago
    In my case it exits the shell upon loading ./v6. I compiled it with gcc 4.2 under OpenBSD 6.4. In happens the same with clang6.
    - szc 8y ago
      IOCCC Judge here: If you are using an xterm, you might try using "xterm -hold". It seems that the termios structure is getting (re)set with some invalid values and some systems (one report from NetBSD) cause the terminal / shell to abort. We are figuring out how to do an update to fix this issue.
flyinghamster 8y ago
I laughed out loud when I got to the part about the PDP-11 emulation being written to run on the emulated PDP-7. That cranks up the hack value to 11.
- dboreham 8y ago
  The Turducken of software.
  - WorldMaker 8y ago
    It's not a true turducken until someone takes the author up on their suggestion to in turn emulate a VAX 780 on top the PDP-11/40 here.
    - dboreham 8y ago
      Turduckens+ all the way down... +A recursively structured arrangement of Turing Machines.

jsolson 8y ago

This is amazing. Make sure to view it on a sufficiently wide browser to see the ASCII art of a torn piece of punched paper tape.

wscott 8y ago
The program would be impressive if it was clearly written and commented.
- bitofhope 8y ago
  The contest is about obfuscated C. Clearly written or not, I'm impressed.
- deleted 8y ago
  [deleted]
a1369209993 8y ago
The binary on the paper tape seems to be ascii (with a parity bit) reading "pdp-7emu.s".

jhallenworld 8y ago

We are in the strange situation with these emulators that all code ever written can be executed today, no problem. Have some Fortran-II code for the IBM 1401? No problem. Want to run some Analytical Engine code (a machine that couldn't even be constructed)? No problem: https://www.fourmilab.ch/babbage/emulator.html https://www.fourmilab.ch/babbage/emulator.html Can you really say that this early code is obsolete? I think not, it's just different.

dboreham 8y ago
That Turing guy was on to something..
beagle3 8y ago
Dolphin runs Wii. Code, Xenia does XBox360 - but the future for XBoxOne emulation looks bleak.
- robdachshund 8y ago
  Eh the new consoles use x86 pc parts. The xbone even runs a windows kernel. It would be less emulation and more just figuring out the supporting software. This is also the case with the original xbox. It's been hard to get working because it uses proprietary nvidia drivers and some weird version of windows 2000.

meatsock 8y ago

typo: "Thompson re-wrote a filesystem emulation he had been experementing with" should be experimenting

macjohnmcc 8y ago

Way back in the early 80's when I was in high school I had an off campus class where I took a course on PDP-11 assembly language. Sadly we had to run our code in a PDP-11 emulator on a DEC System 10 and it was incredibly slow but I do remember how much I liked the PDP-11 instruction set. I wish I had kept the book from the class.

tacon 8y ago
All the old DEC manuals are online. For example, the PDP-11/40 system manual: http://bitsavers.informatik.uni-stuttgart.de/pdf/dec/pdp11/1140/DEC-11-H40SA-A-D_PDP-11_40_System_manual.pdf http://bitsavers.informatik.uni-stuttgart.de/pdf/dec/pdp11/1...

userbinator 8y ago

The short version is we have gone so far back in the history of UNIX that we don’t have filesystem paths yet. Incidentally, the same was true of MS-DOS: no paths in version 1, only drive letters; directories and paths were introduced in version 2. However, early UNIX doesn't seem to have drive letters...

ncmncm 8y ago

This is the best thing I have read this year. I expect I will still be able to say that next month.

nickjj 8y ago

If anyone wants to mess around with a PDP-11 simulator, you can get it up and running with Docker in 1 command. Details are at: https://nickjanetakis.com/blog/run-the-first-edition-of-unix-1972-with-docker https://nickjanetakis.com/blog/run-the-first-edition-of-unix...

kristopolous 8y ago

Where do people like this exist and how can I hire them? Really...

kevinwang 8y ago

Can anyone explain the background of this for a youngin like me whose first computer was Windows XP?