md5 contains the MD5 hash program used to generate the contents of the top-level file `checksums'. fpsim.tar contains a floating-point simulator for 7th Edition, donated by Henry Spencer. Here are the details from the man page: This system provides for software emulation of floating-point instructions if floating-point hardware is not present. The kernel code in question simulates an FP11 floating-point processor by intercepting illegal-instruction traps and decoding and interpreting the floating-point opcodes. This simulator is derived from Bell's, which used signal(2) and was compiled into the user program. Mike Tilson of HCR thought of and did the original kernel-mode simulator; this improved variant by Henry Spencer.