CSFEC is a new Commodore 64 emulator: it passes several tests from the PC64 suite (CPUTIMING, CPUPORT and the entire MOS 6510 opcode set) but fails others (IRQ, NMI and all CIA tests); it supports up to two extra SID chips (either $D420 and $D440 or $DE00 and $DF00) but the VIC-II emulation is incomplete (no badline handling, no sprite contention); it can load PRG files and play T64 and TAP tape images, but it doesn't emulate the C1541 disc drive yet and thus cannot handle D64 disc images at all.