Since it's a highly work-in-progress project, I suggest to try with Chrome as well (lastest version) if you use firefox and vice versa.
The emulator supports some kind of "netconfig", which means the URL can hold configuration for the emulator. As JSep is designed a web application can be "launched" via an URL, this is the natural method, and made it easy to be referenced on other pages, etc
If an option is not specified, the default value is used which can also mean the usage of files from ep.lgb.hu server. But otherwise, JSep always fetches data from the net, even the EXOS rom image, so it's not a very brilliant idea to try to disable EXOS with no, as machine won't boot without any ROM image ...
If you specify some file name _without_ http:// or such where URL is expected then the image is tried to be downloaded from ep.lgb.hu server, so be carefull with this! By the way, you can examine the binary files here, which are used by the emulator. Without proper URL files are fetched from here (which is also the default case for ROM images etc, if you don't specify other values).
If you have a disk image which can be accessed via HTTP (or https or ftp, though they are not tested at all), you can tell JSep to use it. If you also make some EXDOS.INI to launch a problem, you can have an autoload function, by clicking on a single URL to configure+start JSep, your program will start within the emulator after booting. You can also auto-start a single file program with the help of diskhack=load option.
JSep will guess the geometry of the disk image based on its size. It will warn you if it was not successfull. Note: disk images are always treated as double side disks!
Of course, if you disable EXDOS (exdos=no, or non-existing ROM image is given, etc), not even program fetch (diskhack) will work as it operates with on-the-fly created disk, so EXDOS is needed to access it then!
Though this configuration interface seems to be "rough", using URLs is the natural way to provide linkage capability with other pages, so you can refer the emulator from other page. Of course a frontend can be written which uses nice html FORMs to construct URL for the emulator.
The following URL will cause to configure the emulator to use 128K of RAM, start emulation without pressing the "run" button, fetch program file from ep.lgb.hu, and start to run it automatically within the emulator:
Nice Enterprise slide show: CLICK HERE.
Some simplier examples (without loading/disk tricks), click on them: