PCem simulates the BIOS cache, which relies on the processor rather than on system memory. However, unofficial builds of PCem (PCem-X and PCem-unofficial) also supports IBM PC compatible systems/motherboards (from 1996 until 2000) that supports Intel Pentium Pro/Pentium II processors. PCem emulates various IBM PC compatible systems/motherboards from 1981 until 1996, this includes almost all IBM PC models (including the IBM PS/1 model 2121 and the IBM PS/2 model 2011), some American Megatrends BIOS clones (from 1989 until 1994), Award BIOS systems (Award 286 clone, Award SiS 496/497 and Award 430VX PCI), and Intel Premiere/PCI and Intel Advanced/EV motherboards. However, the current developer of PCem has a main concern that the recompiler is not fast enough to emulate the Intel Pentium Pro/Pentium II processors yet. Yet a rather fast processor is needed for full emulation speed (such as an Intel Core i5 at 4 GHz). A recompiler has been added in v10.1, being mandatory for P5 Pentium and Cyrix processors and optional for i486 processors and IDT WinChip processors.
PCem is capable of emulating Intel processors (and its respective clones, including AMD, IDT and Cyrix) from Intel 8088 through the Pentium Tillamook MMX/Mobile MMX processors from 1997 until 1999.
