Research level simulations generally can't be encapsulated in a single hoc file. They may require special model descriptions of membrane channels that have to be translated into c, compiled, and linked with the standard neuron libraries in order to construct a special executable. The interpreter code that runs these simulations may be packaged in separate .hoc files for setup of neuron geometry, specification of membrane properties, and control of the simulation. There may be several .session files which place panels of controls and graphs on the screen in an arrangement convenient for this simulation. Possibly there are data files for fitting the model.
When you download a simulation file with a .nrnzip extension you can automatically run it. The .nrnzip file is a compressed archive file containing all the files required for the simulation. The name of the downloaded zip file is passed to the mos2nrn shell script which is located in $NEURONHOME/bin. This script extracts the files of the zip file, creates a special version of neuron if required, and runs it.
To install this feature you need to edit two files in your
home directory: .mime.types and .mailcap
Add the following lines to $HOME/.mime.types
application/neuron hoc nrn nrnzip
Add the following lines to $HOME/.mailcap
application/neuron; mos2nrn %s
If this feature is installed and your neuron installation is working properly then you will be able to see a propagated action potential by running hhcable.nrnzip. Also, after running that, the hhcable.nrnzip environment can be used by subsequent hoc files to run a variation of the larger simulation. eg. A changeing diameter simulation will download hhcable1.hoc and run it in the directory created by the above hhcable.nrnzip file.
How to serve simulations to others
Before answering the next question here is your opportunity to inspect the files that have been extracted.