DG/UX for x86, CTOS, AOS, and RDOS are already included.
I hadn't included the R1000 emulator because originally they emulated it at the logic gate level and it literally took a week to boot. It looks like they now have a more traditional instruction-level emulator that is supposedly comparable to the real hardware in speed, so I guess I should try to install that.
I think a major reason that no AS/400 emulator exists is because people are afraid of IBM sending them a C&D, although I'm not sure if IBM would care all that much if somebody wrote an emulator for IMPI AS/400s. Those haven't been supported for well over 2 decades AFAIK.
I do know somebody is slowly working on S/32 and S/34 emulators, but they haven't shared either because both apparently are still somewhat flaky. Hopefully they release them at some point. The entire midrange/office computer category is very under-preserved. The only such machines represented in the OS museum currently are HP3000 and S/3.
I've never seen images anywhere for NonStop, VOS, or NIROS, nor do emulators exist for the original hardware they ran on. Later versions of NonStop and VOS run on x86, but I'm not sure if they run under virtualization.
Yeah, I should probably add screenshots of earlier versions of those (or in the case of Domain/OS, screenshots of dm).
Rather than just another name for Domain/OS, Domain/IX was actually a Unix compatibility layer that was an add-on product for pre-SR10 AEGIS versions, with SR10 merging it into the base OS (pre-SR10 had no built-in Unix compatibility).
AFAIK even though it's usually associated more with HP-UX, VUE actually originated at Apollo before HP bought them, although I'm not sure if they ever actually released it before the acquisition.
Sorry for the issues with downloads from earlier. The server I was trying to host it on had a failing disk. I now have torrents up, and the direct download links are to archive.org.
Helios unfortunately isn't yet included. Last time I checked the Transputer emulator doesn't support the special Helios I/O server protocol, which is different from the one that the usual occam software used. It's on my long list of emulators/OSes to fix/finish though.
Multiple versions and variants of OS-9 are included. There are images for NitrOS-9 on CoCo and Dragon, several ports of OS-9/6809, OS-9/68K 2.4 for X68000, and OS-9000/x86 6.1.
I wish I could do that, but there are a lot of emulators that don't have web versions, and the launcher and related scripts are very heavily dependent on a Unix-like OS and there is no way to port them to JS (a completely separate launcher and scripts would have to be written).
It sucks that there's no good way to port Linux directly to WASM UML-style, since WASM insists on implementing memory safety at the bytecode level with no way to bypass it. There is a very limited port, but it doesn't support paging. Not all the emulators would run on a full-featured WASM port if one existed, but that could be dealt with by just using user-mode QEMU to run whichever ones are x86-only.
I haven't yet included a full list, but I guess I could include one.
All of those OSes you mentioned are included. BTRON isn't a single OS, but a small family of OSes based on a common specification (just like Unix is); the OS museum includes the demo 1B/V3 and Chokanji 4. The FOSS BTRON implementation you're thinking of is almost certainly B-free/EOTA, which is also included. EOTA never actually implemented BTRON proper before it got abandoned. It basically just ended up being like a Unix based on an ITRON kernel.
Documentation for some OSes is included, although I've focused more on user/administrator documentation over developer documentation. It would probably be a good idea to include developer documentation though.
I've thought about making individual images available for download, but many of them are dependent on particular emulator versions and/or the common launch scripts so it isn't quite that simple.
I'm not aware of any fully working TENEX images unfortunately. There are partial images, but last time I checked they weren't in a state that was even remotely usable.
The vast majority were downloaded. A few I got when I exchanged compilation DVDs with someone in Finland in 2006 and 2009 (I uploaded the images on those to BetaArchive back then and they've made their way onto various other sites). The only ones that I have that were installed from images I dumped from original media that hadn't been previously shared were LynxOS 4.0 and MaxOS Linux (not to be confused with macOS, it was an obscure early-2000s commercial Slackware fork from a company that was semi-local to me; the CD was given to me back then by somebody at a long-defunct local computer store).
The last version of TempleOS is included, but I installed it myself, and I didn't bother to include most of the images that I just installed by myself in the credits.
I'm also planning to add earlier versions as well as the later forks at some point.
Several different SIMH forks are included, along with a lot of other emulators; there are well over 150 different emulators, with some having multiple versions and variants present to handle things like regressions related to specific OSes.
Nested virtualization for certain x86 OSes running in QEMU is supported, although you will have to enable it manually (VirtualBox has a checkbox for this in its settings). For VMs that support it, the QEMU launch scripts will automatically use KVM if available and fall back to TCG if nested virtualization isn't enabled.
NetWare 4.11 and 6.5 are included, but just don't have any screenshots on the site (the screenshots are not exhaustive at all and just a small sampling of what's there).
And even though there weren't very many 286 protected-mode OSes there were still several of them, with the OS museum including:
1B/V3 (a Japanese OS with an object-oriented desktop and extensive compound document support, part of the TRON project)
Microport SysV/AT
Prologue TwinServer (an obscure French OS that originated on 8080/Z80)
Multiple versions of OS/2 1.x
QNX 2.21
QNX 4.0
IBM PC XENIX
1B and TwinServer are especially notable since they were maintained as 286 OSes long after x86-32 machines had made 286 machines completely obsolete; the last versions apparently being in 1997 for 1B and 2002 for TwinServer (although the last version of TwinServer has some limited support for 32-bit code, it can still run on a 286)
That was Voyetra Audiostation, and I definitely remember having it on the Packard Bell 486 that was my family's first computer (which was already obsolete when we got it, since we got the cheapest machine they had; it was on clearance sale). While I do have Windows 3.10 and 3.11 for Workgroups images, I don't (yet) have one with Audiostation. I have sometimes thought about trying to find the closest PB master CD ISO to the one that came with that machine and install it, but just haven't gotten around to doing that yet (still got lots of other stuff to install).
I hadn't included the R1000 emulator because originally they emulated it at the logic gate level and it literally took a week to boot. It looks like they now have a more traditional instruction-level emulator that is supposedly comparable to the real hardware in speed, so I guess I should try to install that.
I think a major reason that no AS/400 emulator exists is because people are afraid of IBM sending them a C&D, although I'm not sure if IBM would care all that much if somebody wrote an emulator for IMPI AS/400s. Those haven't been supported for well over 2 decades AFAIK.
I do know somebody is slowly working on S/32 and S/34 emulators, but they haven't shared either because both apparently are still somewhat flaky. Hopefully they release them at some point. The entire midrange/office computer category is very under-preserved. The only such machines represented in the OS museum currently are HP3000 and S/3.
I've never seen images anywhere for NonStop, VOS, or NIROS, nor do emulators exist for the original hardware they ran on. Later versions of NonStop and VOS run on x86, but I'm not sure if they run under virtualization.