I am having trouble with getting the PDP-8 emulator to work properly via simh on my Ubuntu 18.04 machine. Are emulator questions on topic for Retrocomputing?
If it's about an emulator simulating an on-topic machine (generally, not a Wintel PC) and the question is not generic enough to apply to other software running on the same OS, yes, it's appropriate here.
In particular, mentioning the host OS is not always a good guide to whether or not the question is on-topic for RCSE. We often may need to know the version of the simulation software you're running, and "I installed the SIMH package on Debian 9" at least lets people look that up, though it would be better to say the version explicitly, in this case "3.8.1-5 from the Debian 9 package." And on something like a Raspberry PI running a (physical) front panel replica, the OS may be relevant to how it's using (and even if it can use) things like the GPIOs for the front panel.
I feel perfectly comfortable saying things like, "Run
apt-get install simh" to cover the software install (rather than going into the details of how to build SIMH from source) if I know the OP's OS and version and it lets me get past those details to get to the meat of the question.
Are emulator questions on topic?
Yes, if the question is about the emulated item, then of course.
No, if it's about the emulator or its modern environment
I am having trouble with getting the PDP-8 emulator to work properly via simh on my Ubuntu 18.04 machine.
This case offers a nice slope to ski down :)
If it is about the PDP-8 programming, or any hardware variation, then it's quite welcome, as it's about the real thing as well.
If it is about setting up a specific PDP-8 within SIMH, then it usually is on topic. Like before, configuring a setup in SIMH is much like plugging boards.
If it's about some quirks in SIMH's implementation of a PDP-8 then it might be on topic. But usually better directed at a SIMH user/maintenance forum than here, as it's about the product SIMH, not the emulated machine.
If it's about setting up SIMH as a software for a specific OS, then it's clearly off-topic, as it's about the workings within a certain OS.
If it's about setting up an OS to host an emulator it as well is clearly off-topic. Like before.
Personally I find it a good criterion to look if naming OS and it's version is considered necessary. If yes, then chances are good it's off-topic. Similar for the version of an emulator or any scripting, inbetween.