IBMulator is a free/libre, open source emulator for the IBM PS/1, able to run with the original ROM. The goal is to create a faithful simulator capable of recreating the look and feel of the real machine.
Currently IBMulator emulates the PS/1 models 2011 (286) and 2121 (386).
The program is in active development and still in a beta status, so expect bugs and missing features.
Official project site
GIT repository
Precompiled binaries

IBMulator v0.12 with the Munt MT-32 emulator