Simics is a very mature simulator with a long history. It first appeared around 1997(SimICS/sun4m), modeling sun4m machine and support to bring-up Solaris 2.6. It is about 6 years before QEMU's first release(2003). But for roughly 2 decades it was marketed and sold by Virtutech and later Wind River, and only became freely available to the public as intel Simics after 2022.
