Well, OK, there's one other wrinkle. Building Frotz on 4.3BSD (or whatever) on a VAX would be easy, because you have a 32-bit address space. But the Z-machine can address 64Kwords (plus some trickiness for access strings in high memory) so you'd have to actually implement a segmented memory model or overlays or something to squeeze it into a PDP-11. Which is obviously doable--after all, the Z-machine was designed to be implemented on 8-bit micros!--but means that porting Frotz might be more work than just writing a new interpreter, and supporting the later, larger games (Infocom used the v5 format, which doubled the size and required 128K even on 8-bit systems, and a lot of the post-Infocom community work--before the community went to Glulx, which is a 32-bit-inspired-by-the-z-machine-virtual-machine-for-text-adventures--used z8, which doubled the size again) is going to be harder. Jimmy Maher has just been talking about the evolution of the Z-machine over on filfre.net. It's well worth reading. Adam On Fri, Dec 6, 2019 at 6:22 PM Adam Thornton wrote: > There was not a Z-Machine interpreter for Unix machines, as far as I know, > until the release of the ITF interpreter in the early 90s. > > However.... > > Zork was developed under ITS (when it was "mainframe Zork" and an MIT > student project), and the later Infocom games were developed under TOPS-20. > > As it happens, I've fairly recently ported the "Frotz" Z-Machine > interpreter to TOPS-20. https://github.com/athornton/tops20-frotz and > https://github.com/athornton/gnusto-frotz-tops20 > > This was not all _that_ hard. KCC on TOPS-20 is an ANSI C compiler, so > there were basically two classes of problems to solve. > > The first one is that the linker requires all symbols that are linked > between modules to be six characters or shorter (and case is folded), so I > wrote a transmogrifier (gnusto-frotz) to extract those symbols and create a > mapping for them so that the object code would link. > > The second problem was that the Frotz source assumes 8-bit bytes and that > your word length is a multiple of 8 bits. Since the Z-machine is a 16-bit > virtual machine, that meant there was a whole lot of bit masking necessary > in the opcodes and memory references in order to represent the Z-machine > memory correctly within the TOPS-20 address space. That's done with stuff > like: > > > https://github.com/athornton/tops20-frotz/blob/0130a67fc44e0c7de1faa8f882cbc28faee76756/frotz.h#L488 > > So the idea is, gnusto-frotz-tops20 is semantically equivalent to regular > Frotz, but with macros changed so if you build it with -DWEIRD_WORDSIZE it > would build on a 36-bit system. Then once you've modified the source, you > run it through the transmogrifier (which really just generates a sed > script) to get something that will _link_ on a 36-bit system. > > I have vague plans to port Frotz to ITS but the problem there is that the > C compiler is pre-K&R rather than ANSI, so there's a lot of deprotoization > work to be done, and _then_ I need to fix the things like += being =+ and > so forth, and I think I have to chop another character off the symbols, > which may mean I need smarter collision detection. So it's nontrivial. > > Maybe a good first step would be unprotoizing Frotz and getting it to > build on v7 or so... > > Adam > > On Fri, Dec 6, 2019 at 3:52 AM Gabriel Diaz wrote: > >> Hello, >> >> >> Source code has been published of some early games. >> >> Were those games playable on Unix machines at the time? What was your >> favourite game? >> >> >> >> https://kryptonradio.com/2019/04/18/zork-source-code-presumed-lost-forever-has-been-uploaded-to-github/ >> >> >> Gabi >> >> >> >> >>