http://3cbzkrvakrpetjjppdwzbzqrlkmzatjs7jbyazap5gwutj32gcltjpqd.onion
Instead we deploy a "real BDOS" in RAM that will route system-calls to our host emulator via a clever trick. For BDOS functions the C-register will contain the system call to operate, our complete BDOS implementation is: OUT (C),C
RET The host program can catch writes to output ports, and will know that "OUT (3), 3" means "Invoke system call #3", for example.