emulators/sys161 2.0.8 NetBSD

System/161 is a machine simulator that provides a simplified but still realistic environment for OS hacking. It is a 32-bit MIPS system supporting up to 32 processors, with up to 31 hardware slots each holding a single simple device (disk, console, network, etc.)

It is used for teaching; the OS/161 instructional OS runs on it. However, it has also proven useful as a rapid development platform for bringing up research or experimental kernels.

System/161 supports fully transparent debugging, via remote gdb into the simulator. It also provides transparent kernel profiling, statistical monitoring, event tracing (down to the level of individual machine instructions) and one can connect multiple running System/161 instances together into a network using a "hub" program.