10 ms·

Show HN: Resurrecting Infocom's Unix Z-Machine with Cosmopolitan

I recently brought Infocom's original UNIX z-machine source code back to life on modern systems. The modified source code, instructions on usage, a build of the z-machine, and examples of embedded game executables are available. There is also a detailed write-up about the state of the original source code, the porting process, and the invaluable role Justine Tunney's Cosmpolitan project played in bringing the Zork trilogy (and more) to Windows/Mac/Linux/bsd for arm/x86 machines over the course of a lazy Sunday.

wyldfire 2y ago
Funny coincidental timing - I just played HHGTTG a couple of times last night for the first time in thirty+ years or so. I first played the game, way back - prior to having read the novel. It was mind-blowing. I had no idea what was going on but I got a real sense that it could be pretty funny if I did. So I read the novel eventually, and it was as good as I expected. I don't think I'd gone back to play the game until this week, though.
- ChristopherDrum 2y ago
  It had never occurred to me that someone might have the game be their first HHGTTG experience over some other media. For me, the BBC television series was my gateway into the world, then the game (I was already hooked on Infocom by then), then the books. HHGTTG is a .z3 game and is compatible with this project's build of the Infocom source, should you get the urge to play again in another 30 years.
  - dcsan 2y ago
    BBC tv or radio? Seems odd now to think back to a fixed time radio broadcast but I loved the radio show
    - Brian_K_White 2y ago
      They aren't misremembering, there was a tv series.
      - dsr_ 2y ago
        The most interesting part is that of all the Hitchhikers' media, only the original radio series and their published scripts are in complete agreement with each other on all details of world-building.
    - ChristopherDrum 2y ago
      TV series, absolutely; I've actually never heard the radio program. It aired on PBS in my area along with Monty Python, The Young Ones, and other shows from "across the pond."
bruce511 2y ago
Its interesting to see how developers get into a mindset, based on their life experience. What we're seeing here is 40 year old code compile and run with minimal effort. Largely because the C language has respected backwards compatibility. Yes, there were breaking changes along the way, but they were trivial to resolve in hours. And (more interesting) the author believed that to be true and so persevered. I saw this recently as well. I run a lot of programs on Windows. Many are 32 bit, written in the 90s for Windows 95, or 98. They all still run. Microsoft bends over backwards to keep things compatible. I also get to write a lot of web API clients. I tell customers that it won't work forever. Web APIs are constantly changing. The service (especially Google) will change something soon to break it. The people building those APIs are expecting only currently-maintained apps to run. They have no concept (or experience) of 40 or 30 year old code "just running". Crumbs, if you get 5 years out an API client you're doing well.
- ChristopherDrum 2y ago
  Yeah, the "porting" part was pretty trivial, all things considered. Any difficulty was really only as a consequence of certain patterns being unfamiliar or evolved. Once those patterns were identified, it was only "roll up your sleeves and do the work" to get it going again. Working on this kind of got me re-thinking my approach to my personal projects again. What can I do today to best ensure my own code will be this easy to run in 30 years? As a corollary to that, what can I build today that will be interesting enough to want to run again in 30 years?
- BrenBarn 2y ago
  I think part of that is because those old Windows apps were distributed and forgotten about. There was no update procedure for many of them, and if there was it was just "buy a new disk" or at most "check the website and download a new EXE". Now that people have always-on internet connections, they expect to be able to get things instantly, and companies then expect to be able to push their updates instantly, and other companies expect that they can push their own update if someone else breaks their API, and so on and so forth until everyone expects everyone to have "the latest version" of everything. It's the era of constant updates. I find it pretty annoying.
joshu 2y ago
i think ucsd p-system vm predates z-machine by a couple of years (re OP's origin of vm use comment)
- ChristopherDrum 2y ago
  Interesting to know, thanks. My intention with that comment was in pondering about vms distributed commercially in the home market, which I don't think I made clear enough in the post. :/
  - ssrc 2y ago
    What's remarkable about Infocom's z-machine is the level of sophistication and polish vs the intended application, maybe unsurprising coming from MIT graduates with access to a PDP-10 as a development platform. Otherwise the use of virtual machines was, maybe not common, but not unusual. * TinyBasic (1975) was specified (and sometimes implemented) as a VM https://en.wikipedia.org/wiki/Tiny_BASIC https://en.wikipedia.org/wiki/Tiny_BASIC * Apple Pascal (1979) was a UCSD Pascal system. https://en.wikipedia.org/wiki/Apple_Pascal https://en.wikipedia.org/wiki/Apple_Pascal * The COSMAC VIP computer/console's (1977) games were programmed in CHIP-8, a VM. https://en.wikipedia.org/wiki/CHIP-8 https://en.wikipedia.org/wiki/CHIP-8 * Scott Adams' text adventures (1978+) used an application-specific VM. https://en.wikipedia.org/wiki/Adventure_International https://en.wikipedia.org/wiki/Adventure_International * Wozniak's SWEET16 contained in Apple II Integer Basic (1977) https://en.wikipedia.org/wiki/SWEET16 https://en.wikipedia.org/wiki/SWEET16 * If you count Forth as a VM, it was pretty common. https://en.wikipedia.org/wiki/Forth_(programming_language) https://en.wikipedia.org/wiki/Forth_(programming_language)
    - ForOldHack 2y ago
      You must have done little research to remember those. I knew all but two. (COmSAC and Sweet16). I wonder if the wikipedia articles are lucky enough to be good...
  - flonkyflonk 2y ago
    Blank and Berez were definitely thinking about p-machines when they designed the Z machine, and there is a hat tip in the 1980 Creative Computing article describing its inner workings. [1]: https://mud.co.uk/richard/htflpism.htm https://mud.co.uk/richard/htflpism.htm
user3939382 2y ago
This is somewhat tangential to the precise topic but since it doesn’t come up often: if you’re into this genre I recommend a game called Vespers. Really well done and thick atmosphere.
- ChristopherDrum 2y ago
  My absolute favorite text adventure in recent years is Lost Pig. Alas, it is not compatible with the UNIX port this post is about, but it is a delightful game with a unique comedic voice.
- colkassad 2y ago
  Vespers is great. I also recommend the classic Lovecraftian adventure, Anchorhead.
o11c 2y ago
In case anyone needs to do the sort of "fix up scattered declarations and move them to headers", you really want to use: gcc -Werror=missing-declarations -Werror=redundant-decls (last I checked, Clang's implementation of this was buggy and half-useless, but I'll admit I stopped using Clang) I recommend this for well-maintained code too, just as another way to keep the code smells away. For a lot of projects this will only require adding a bit of `static` that you were too lazy to write.
- ryao 2y ago
  I suggest -Wall -Werror for code hygiene.
  - o11c 2y ago
    I recommend against global -Werror, instead use -Werror= with each individual option to make it much easier to deal with compiler upgrades that change warnings. For well-maintained code, -Werror=all is expected, but switching to it is not trivial in a nasty codebase. It's still worth doing, but it's a whole project. -Werror=extra is also a good idea once your codebase is clean for all of the above, but you will need to learn to write suppressions, and some of those are compiler-specific. -Werror=format=2 (requires adding attributes) and -Werror=unused (weird version-dependent interactions with other warnings, so better enable it explicitly) are next, then there's a long tail of obscure warning options that should be considered; many are useful but others should be explicitly disregarded (one particular question of interest that stick out: how hard is it to suppress/restore this within a macro). Past the trivial, Clang's warnings tend to suck (and they often refuse patches even for parity); GCC's are more useful due to the strength of history. It's still worth using Clang just for the fact that it uses different logic for triggering warnings (and also different warnings available; -Weverything is great for discoverability); just be aware that `__has_warning` isn't very useful (what we really need is `__has_warning_that_actually_works_correctly`, which requires hard-coding known-bug-free compiler versions).
deleted 2y ago
[deleted]
fredsmith219 2y ago
Absolutely amazing. Good work. It downloaded and ran on Arch with no problem.
- ChristopherDrum 2y ago
  Fantastic to hear! Thanks for the kind words and for checking it out.
hans_0l0 2y ago
What is going on here? [~/Downloads] $ chmod +x zork* [~/Downloads] $ ./zork1 Cannot open assembly './zork1': File does not contain a valid CIL image.
- jchw 2y ago
  Do you have some sort of binfmt_misc setup for Windows/.NET executables? You might be able to get it to work by running `sh ./zork1` instead.
  - hans_0l0 2y ago
    Yay, this works :-) West of House You are standing in an open field west of a white house, with a boarded front door. There is a small mailbox here.
    - ChristopherDrum 2y ago
      Wonderful, thanks for playing!
- ChristopherDrum 2y ago
  What setup are you running it on? That will help with troubleshooting. Or, if you prefer, feel free to file an issue on the project repo and we can hash it out there. https://github.com/ChristopherDrum/pez/issues https://github.com/ChristopherDrum/pez/issues
  - hans_0l0 2y ago
    I run Arch Linux on an AMD Ryzen 5. I have mono installed, not sure why, i guess it is a depenency for sdrsharp or the like. However, the sh ./zork1 did the trick :-)
    - ChristopherDrum 2y ago
      Great! Glad to hear we have a simple solution for this issue. It is interesting to note your trouble, because another player in this post is running Arch and says it worked flawlessly. I guess Mono gets in the way a little.
PaulHoule 2y ago
(1) The UCSD p-Machine was contemporaneous and made it feasible to compile Pascal for machines like the 6502 which were terrible targets for conventional compilers. It was atrocious in every way, particularly atrociously slow. At the time many CS professors with Microsoft BASIC being the dominant teaching languages but UCSD plus the inability to do systems programming in ISO Pascal made a generation of young programmers hate Pascal with passion. (2) Scott Adams made an adventure interpreter was was similar but less sophisticated than the z-machine but similarly portable, in fact you could write a Scott Adams interpreter in BASIC [1] but he also wrote interpreters in assembly for the most popular platforms https://6502disassembly.com/a2-scott-adams/interp.html https://6502disassembly.com/a2-scott-adams/interp.html (3) Infocom developed the games on a PDP-10 machine which might be the last general purpose computer that survived with other than the 8-bit byte. (Though it had bitwise addressing which helped it cope with the industry going in that direction). [1] Notably if you tried to write an adventure game in straight up BASIC you'd struggle. It's not like you could look up a verb in a hashtable and dispatch to subroutine. You'd be writing incredibly long if-then-else ladders nested inside if-then-else ladders which is bad enough in a civilized language.
- ghaff 2y ago
  The Infocom games were also super-tight on memory. There’s a presentation by Dave Liebling I think at some game developers conference on YouTube someplace that goes into this among other things.
  - PaulHoule 2y ago
    Here was the 1980 explanation https://archive.org/details/creativecomputing-1980-07/page/n81/mode/2up https://archive.org/details/creativecomputing-1980-07/page/n...
  - Thoreandan 2y ago
    Game Developers Conference Classic Gaming Postmortem: Zork (2014) "Dave Lebling, co-author of Zork and co-founder of Infocom, gives a postmortem talk on the classic text adventure. Lebling, who currently works as a senior principal software engineer at BAE Systems, created the "grue," co-authored Zork I-III and wrote seven other text adventures. He plans to give an hour-long talk explaining, among other things, the creation of both the mainframe and microcomputer versions of Zork, the trials and tribulations of coding a cutting-edge text parser, and what it was like to experiment with self-publishing at a time when most PC games were sold in hand-packed plastic bags. https://www.gdcvault.com/play/1020612/Classic-Game-Postmortem https://www.gdcvault.com/play/1020612/Classic-Game-Postmorte... https://archive.org/details/GDC2014Lebling https://archive.org/details/GDC2014Lebling
gamache 2y ago
Cool project! But one nitpick. K&R C has no concept of THEN. That's a peculiarity of the ZIP source code, defined as a pure no-op: #define THEN https://github.com/ChristopherDrum/pez/blob/main/zip/infocom_source/phg_zipdefs.h#L170 https://github.com/ChristopherDrum/pez/blob/main/zip/infocom...
- pcwalton 2y ago
  It's Bournegol [1]! [1]: https://oldhome.schmorp.de/marc/bournegol.html https://oldhome.schmorp.de/marc/bournegol.html
- ChristopherDrum 2y ago
  Oh wow, thank you for the clarification. I completely didn't even consider to audit for that in the ZIP source (though the ALL CAPS maybe should have been my hint). I'll update the post with this and another small thing another player found.

wyldfire 2y ago

Funny coincidental timing - I just played HHGTTG a couple of times last night for the first time in thirty+ years or so. I first played the game, way back - prior to having read the novel. It was mind-blowing. I had no idea what was going on but I got a real sense that it could be pretty funny if I did. So I read the novel eventually, and it was as good as I expected. I don't think I'd gone back to play the game until this week, though.

ChristopherDrum 2y ago
It had never occurred to me that someone might have the game be their first HHGTTG experience over some other media. For me, the BBC television series was my gateway into the world, then the game (I was already hooked on Infocom by then), then the books. HHGTTG is a .z3 game and is compatible with this project's build of the Infocom source, should you get the urge to play again in another 30 years.
- dcsan 2y ago
  BBC tv or radio? Seems odd now to think back to a fixed time radio broadcast but I loved the radio show
  - Brian_K_White 2y ago
    They aren't misremembering, there was a tv series.
    - dsr_ 2y ago
      The most interesting part is that of all the Hitchhikers' media, only the original radio series and their published scripts are in complete agreement with each other on all details of world-building.
  - ChristopherDrum 2y ago
    TV series, absolutely; I've actually never heard the radio program. It aired on PBS in my area along with Monty Python, The Young Ones, and other shows from "across the pond."

bruce511 2y ago

Its interesting to see how developers get into a mindset, based on their life experience. What we're seeing here is 40 year old code compile and run with minimal effort. Largely because the C language has respected backwards compatibility. Yes, there were breaking changes along the way, but they were trivial to resolve in hours. And (more interesting) the author believed that to be true and so persevered. I saw this recently as well. I run a lot of programs on Windows. Many are 32 bit, written in the 90s for Windows 95, or 98. They all still run. Microsoft bends over backwards to keep things compatible. I also get to write a lot of web API clients. I tell customers that it won't work forever. Web APIs are constantly changing. The service (especially Google) will change something soon to break it. The people building those APIs are expecting only currently-maintained apps to run. They have no concept (or experience) of 40 or 30 year old code "just running". Crumbs, if you get 5 years out an API client you're doing well.

ChristopherDrum 2y ago
Yeah, the "porting" part was pretty trivial, all things considered. Any difficulty was really only as a consequence of certain patterns being unfamiliar or evolved. Once those patterns were identified, it was only "roll up your sleeves and do the work" to get it going again. Working on this kind of got me re-thinking my approach to my personal projects again. What can I do today to best ensure my own code will be this easy to run in 30 years? As a corollary to that, what can I build today that will be interesting enough to want to run again in 30 years?
BrenBarn 2y ago
I think part of that is because those old Windows apps were distributed and forgotten about. There was no update procedure for many of them, and if there was it was just "buy a new disk" or at most "check the website and download a new EXE". Now that people have always-on internet connections, they expect to be able to get things instantly, and companies then expect to be able to push their updates instantly, and other companies expect that they can push their own update if someone else breaks their API, and so on and so forth until everyone expects everyone to have "the latest version" of everything. It's the era of constant updates. I find it pretty annoying.

joshu 2y ago

i think ucsd p-system vm predates z-machine by a couple of years (re OP's origin of vm use comment)

ChristopherDrum 2y ago
Interesting to know, thanks. My intention with that comment was in pondering about vms distributed commercially in the home market, which I don't think I made clear enough in the post. :/
- ssrc 2y ago
  What's remarkable about Infocom's z-machine is the level of sophistication and polish vs the intended application, maybe unsurprising coming from MIT graduates with access to a PDP-10 as a development platform. Otherwise the use of virtual machines was, maybe not common, but not unusual. * TinyBasic (1975) was specified (and sometimes implemented) as a VM https://en.wikipedia.org/wiki/Tiny_BASIC https://en.wikipedia.org/wiki/Tiny_BASIC * Apple Pascal (1979) was a UCSD Pascal system. https://en.wikipedia.org/wiki/Apple_Pascal https://en.wikipedia.org/wiki/Apple_Pascal * The COSMAC VIP computer/console's (1977) games were programmed in CHIP-8, a VM. https://en.wikipedia.org/wiki/CHIP-8 https://en.wikipedia.org/wiki/CHIP-8 * Scott Adams' text adventures (1978+) used an application-specific VM. https://en.wikipedia.org/wiki/Adventure_International https://en.wikipedia.org/wiki/Adventure_International * Wozniak's SWEET16 contained in Apple II Integer Basic (1977) https://en.wikipedia.org/wiki/SWEET16 https://en.wikipedia.org/wiki/SWEET16 * If you count Forth as a VM, it was pretty common. https://en.wikipedia.org/wiki/Forth_(programming_language) https://en.wikipedia.org/wiki/Forth_(programming_language)
  - ForOldHack 2y ago
    You must have done little research to remember those. I knew all but two. (COmSAC and Sweet16). I wonder if the wikipedia articles are lucky enough to be good...
- flonkyflonk 2y ago
  Blank and Berez were definitely thinking about p-machines when they designed the Z machine, and there is a hat tip in the 1980 Creative Computing article describing its inner workings. [1]: https://mud.co.uk/richard/htflpism.htm https://mud.co.uk/richard/htflpism.htm

user3939382 2y ago

This is somewhat tangential to the precise topic but since it doesn’t come up often: if you’re into this genre I recommend a game called Vespers. Really well done and thick atmosphere.

ChristopherDrum 2y ago
My absolute favorite text adventure in recent years is Lost Pig. Alas, it is not compatible with the UNIX port this post is about, but it is a delightful game with a unique comedic voice.
colkassad 2y ago
Vespers is great. I also recommend the classic Lovecraftian adventure, Anchorhead.

o11c 2y ago

In case anyone needs to do the sort of "fix up scattered declarations and move them to headers", you really want to use: gcc -Werror=missing-declarations -Werror=redundant-decls (last I checked, Clang's implementation of this was buggy and half-useless, but I'll admit I stopped using Clang) I recommend this for well-maintained code too, just as another way to keep the code smells away. For a lot of projects this will only require adding a bit of `static` that you were too lazy to write.

ryao 2y ago
I suggest -Wall -Werror for code hygiene.
- o11c 2y ago
  I recommend against global -Werror, instead use -Werror= with each individual option to make it much easier to deal with compiler upgrades that change warnings. For well-maintained code, -Werror=all is expected, but switching to it is not trivial in a nasty codebase. It's still worth doing, but it's a whole project. -Werror=extra is also a good idea once your codebase is clean for all of the above, but you will need to learn to write suppressions, and some of those are compiler-specific. -Werror=format=2 (requires adding attributes) and -Werror=unused (weird version-dependent interactions with other warnings, so better enable it explicitly) are next, then there's a long tail of obscure warning options that should be considered; many are useful but others should be explicitly disregarded (one particular question of interest that stick out: how hard is it to suppress/restore this within a macro). Past the trivial, Clang's warnings tend to suck (and they often refuse patches even for parity); GCC's are more useful due to the strength of history. It's still worth using Clang just for the fact that it uses different logic for triggering warnings (and also different warnings available; -Weverything is great for discoverability); just be aware that `__has_warning` isn't very useful (what we really need is `__has_warning_that_actually_works_correctly`, which requires hard-coding known-bug-free compiler versions).

deleted 2y ago

[deleted]

fredsmith219 2y ago

Absolutely amazing. Good work. It downloaded and ran on Arch with no problem.

ChristopherDrum 2y ago
Fantastic to hear! Thanks for the kind words and for checking it out.

hans_0l0 2y ago

What is going on here? [~/Downloads] $ chmod +x zork* [~/Downloads] $ ./zork1 Cannot open assembly './zork1': File does not contain a valid CIL image.

jchw 2y ago
Do you have some sort of binfmt_misc setup for Windows/.NET executables? You might be able to get it to work by running `sh ./zork1` instead.
- hans_0l0 2y ago
  Yay, this works :-) West of House You are standing in an open field west of a white house, with a boarded front door. There is a small mailbox here.
  - ChristopherDrum 2y ago
    Wonderful, thanks for playing!
ChristopherDrum 2y ago
What setup are you running it on? That will help with troubleshooting. Or, if you prefer, feel free to file an issue on the project repo and we can hash it out there. https://github.com/ChristopherDrum/pez/issues https://github.com/ChristopherDrum/pez/issues
- hans_0l0 2y ago
  I run Arch Linux on an AMD Ryzen 5. I have mono installed, not sure why, i guess it is a depenency for sdrsharp or the like. However, the sh ./zork1 did the trick :-)
  - ChristopherDrum 2y ago
    Great! Glad to hear we have a simple solution for this issue. It is interesting to note your trouble, because another player in this post is running Arch and says it worked flawlessly. I guess Mono gets in the way a little.

PaulHoule 2y ago

(1) The UCSD p-Machine was contemporaneous and made it feasible to compile Pascal for machines like the 6502 which were terrible targets for conventional compilers. It was atrocious in every way, particularly atrociously slow. At the time many CS professors with Microsoft BASIC being the dominant teaching languages but UCSD plus the inability to do systems programming in ISO Pascal made a generation of young programmers hate Pascal with passion. (2) Scott Adams made an adventure interpreter was was similar but less sophisticated than the z-machine but similarly portable, in fact you could write a Scott Adams interpreter in BASIC [1] but he also wrote interpreters in assembly for the most popular platforms https://6502disassembly.com/a2-scott-adams/interp.html https://6502disassembly.com/a2-scott-adams/interp.html (3) Infocom developed the games on a PDP-10 machine which might be the last general purpose computer that survived with other than the 8-bit byte. (Though it had bitwise addressing which helped it cope with the industry going in that direction). [1] Notably if you tried to write an adventure game in straight up BASIC you'd struggle. It's not like you could look up a verb in a hashtable and dispatch to subroutine. You'd be writing incredibly long if-then-else ladders nested inside if-then-else ladders which is bad enough in a civilized language.

ghaff 2y ago
The Infocom games were also super-tight on memory. There’s a presentation by Dave Liebling I think at some game developers conference on YouTube someplace that goes into this among other things.
- PaulHoule 2y ago
  Here was the 1980 explanation https://archive.org/details/creativecomputing-1980-07/page/n81/mode/2up https://archive.org/details/creativecomputing-1980-07/page/n...
- Thoreandan 2y ago
  Game Developers Conference Classic Gaming Postmortem: Zork (2014) "Dave Lebling, co-author of Zork and co-founder of Infocom, gives a postmortem talk on the classic text adventure. Lebling, who currently works as a senior principal software engineer at BAE Systems, created the "grue," co-authored Zork I-III and wrote seven other text adventures. He plans to give an hour-long talk explaining, among other things, the creation of both the mainframe and microcomputer versions of Zork, the trials and tribulations of coding a cutting-edge text parser, and what it was like to experiment with self-publishing at a time when most PC games were sold in hand-packed plastic bags. https://www.gdcvault.com/play/1020612/Classic-Game-Postmortem https://www.gdcvault.com/play/1020612/Classic-Game-Postmorte... https://archive.org/details/GDC2014Lebling https://archive.org/details/GDC2014Lebling

gamache 2y ago

Cool project! But one nitpick. K&R C has no concept of THEN. That's a peculiarity of the ZIP source code, defined as a pure no-op: #define THEN https://github.com/ChristopherDrum/pez/blob/main/zip/infocom_source/phg_zipdefs.h#L170 https://github.com/ChristopherDrum/pez/blob/main/zip/infocom...

pcwalton 2y ago
It's Bournegol [1]! [1]: https://oldhome.schmorp.de/marc/bournegol.html https://oldhome.schmorp.de/marc/bournegol.html
ChristopherDrum 2y ago
Oh wow, thank you for the clarification. I completely didn't even consider to audit for that in the ZIP source (though the ALL CAPS maybe should have been my hint). I'll update the post with this and another small thing another player found.