Infocom ported their Z-machine to nearly every viable platform in the 70s and 80s. Zork runs on around 18 different 8/16 bit platforms using earlier versions of the Z-machine. Why was Z6 the graphical version of the Z-machine ported to the Apple II, but not the IIgs?

1 Answer 1


I suspect it was too late in the game for Infocom... The Apple II port of YZIP, Infocom’s Z6 interpreter, was released in 1989 (as far as I can determine), and by then Infocom was only a publishing house inside Activision, and was about to be shut down entirely.

I imagine that, given the limited development resources available, Infocom would have preferred porting the interpreter to entirely new platforms (new to YZIP anyway, such as the Atari ST), before spending time creating a IIGS-specific port (since the IIGS could run the Apple II interpreter just fine, in IIe mode). There were only four games affected by this anyway (Arthur, Journey, Shōgun, and Zork Zero)...

The IIGS did get specific ports of Z-machine interpreters later on, for The Lost Treasures of Infocom, but they only support Z3 and Z5 games (so Zork Zero, which was part of the compilation on other platforms, isn’t included in the IIGS version). I can only guess why these didn’t support Z6, but I suspect that the effort involved was deemed too great for a single game (LTOI 1 included Zork Zero, and the floppy-based releases of LTOI 2, which were only released on the Mac and PC anyway, didn’t include a single Z6 game).

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    Yes, but The Lost Treasures of Infocom was a significant port to the IIgs, so Z6 could have been ported then. Commented May 3, 2019 at 15:35
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    But not by Infocom; or was your question more general than only Infocom? Commented May 3, 2019 at 15:44
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    For that matter, if the question is intended to be open-ended in that manner, then it's based on a partly faulty premise. The Frotz interpreter has been ported to the GS and, at least according to this page, has at least partial Z6 support on the platform.
    – jmbpiano
    Commented May 3, 2019 at 17:48
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    @scruss compare the Apple II screenshots of Zork Zero to the Amiga versions... A IIGS-specific port would have benefited from the higher resolution, even if it didn’t provide any more colours. Commented May 4, 2019 at 16:21
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    The IIgs version of Lost Treasures was handled by Big Red Computer Club, not Activision/Infocom. However, a IIgs version of Beyond Zork (Z5) WAS released by Infocom in 1988. BZ appears to be C code compiled with APW C. LT was compiled with ORCA/C. BRCC said they were "unable to obtain a license for" the Z6 interpreter. Possibly as part of their license deal, BRCC only had access to the IIgs BZ source code Commented May 4, 2019 at 18:04

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