SuperProbe
The XFree86 utility that guessed which graphics card you had by poking directly at its registers.
XFree86 3.x shipped a separate server per chip family — XF86_S3, XF86_Mach64, XF86_SVGA and so on — so anyone installing Linux on a PC needed to know exactly what was on the card. The box rarely said anything useful. SuperProbe, written by David Wexelblat, read BIOS signatures and tested known I/O ports to identify the chipset, the RAMDAC and the amount of video memory.
The man page warned plainly that probing could lock up the machine, and it was right: writing to the wrong port on the wrong card was a reliable route to a black screen and a reboot. When XFree86 4.0 arrived in 2000 with a single server and modular drivers that could recognise hardware on their own, the tool had nothing left to do.