I like to share with you inputs a I got for a similar inquiry:
I almost never use the simulator; but from my limited experience I agree with you that it’s not possible to use the Simulator for Ethernet communications. I think the only way this would work is if Zilog were to create a virtual ‘Ethernet’ driver for the PC – which ain’t gonna happen anytime soon… The idea is the virtual driver provides Simulator with indirect path to PC’s TCP/IP stack. Therefore PC apps can communicate with the Simulator in the same way that they can send packets through a physical NIC to external devices.
A simpler approach could be to provide a mock Ethernet output window in the simulator similar to what’s done with the UART – but this is in the ‘too cumbersome to possibly be useful’ category. E.g. if the eZ80 application was to send a 1500 byte Ethernet packet then the simulated Ethernet output window would fill up with 1500 hexadecimal values. Then to simulate receiving a 1500 byte response packet the user could type in 1500 hexadecimal characters and the Ethernet Simulator could pass these to the F91 MAC… don’t think so…
While the simulator is very useful for compiler testing, it’s difficult for me to envision a situation where an embedded developer would find it very helpful. It’s useful for stepping through compiled code and verifying that it behaves as expected in the absence of any interrupts or changes in inputs.
A dream feature of mine has been to develop an interface so that a C or C# program could monitor the simulator, driving all the inputs and watching all the outputs, to simulate whatever their hardware under development was expected to do. For eZ80, we might also add some reasonably humane way to monitor Ethernet output from the simulated device. (Something easier than watching the changing values on a pin.)
Documentation on the simulator is, to my knowledge, non-existent.