Exopc is not yet self-hosting. This means that it must be compiled under a different operating system than itself. Currently, exopc must be built under OpenBSD or Linux, though FreeBSD or NetBSD probably work too. We use either OpenBSD 2.2 with gcc 2.7.2 or linux 2.0.x with libc6. Exopc uses the same binary format as OpenBSD. This means that if you're compiling under linux you have to use a cross compiler that generates OpenBSD binaries. We have included binaries for gcc 2.7.2 setup to cross compile in this distribution. To use this cross-compiler, untar tools/linux-cross/cross-tools-libc6.tgz under /usr/local/openbsd-cross.
Booting is poorly supported right now. Either you have to boot with OpenBSD's boot blocks (not supplied) or with the supplied DOS boot-loader. OpenBSD's boot blocks expect the kernel to be in an OpenBSD filesystem. Other boot-loaders should work. It would be nice to find one that didn't require us to have an OpenBSD filesystem and which could load both linux and OpenBSD kernels.
Exopc currently only supports the following hardware: NCR 810/815/875 SCSI controllers and SMC Elite16, EtherEZ, and EtherPower 10/100 ethernet cards. You have to have an ethernet card, but a local disk is optional. At least a Pentium processor is required. Any color display adapter should work.