I was trying to get the PC compatibility card (a Gemini II) in my Risc PC (StrongARM, running RISC OS 3.70) onto the network. However, when starting the emulated PC, I would get a “Not a heap block” error, and the emulated PC wouldn’t have its emulated network card.
First, on the PC side, make sure you have the right settings. The I/O address of the emulated NE2000 is 0x340, not 0x300 like usual. The IRQ is set through the RISC OS side setup GUI; you may have to select a different value if it conflicts with another device.
It turns out this is because the program it invokes to find the most appropriate interface (this is called ScanDCI4) doesn’t actually work. This causes the script to fail, and not actually load the emulated NE2000 support module. To fix this, we’ll need to patch the script that starts the PC card networking support.