Previous is a NeXT Computer emulator that can boot NeXTStep 0.x to 4.0 beta and OpenStep 4.2 For Mach.

Previous is a NeXT Computer emulator based on the Atari emulator Hatari. It uses the latest m68k emulation core from WinUAE and the i860 emulator from Jason Eckhardt. Previous is confirmed to compile and run on Linux, Mac OS X and Windows. It may also work on other Systems which are supported by the SDL2 library

While the Github project mirror has been archived in 2021, there is still some recent activity on SourceForge: https://sourceforge.net/p/previous/code/HEAD/tree/branches/