I bought two NCD Explora 451 X terminals on eBay for $20 each. They have an IBM 403GCX processor, PCNET-fast 10/100 ethernet and an S3 video chip. I thought thew would make a nice linux based X terminal.
Getting the existing boot prom to read my ELF files required some perseverance but I managed to figure it out. Once that was done I wrote a simple standalong program to test hardware assumptions. Once I got the screen and serial port working I did a simple linux board port, using the current linuxppc_2_4_devel tree.
The box now boots a kernel via tftp and runs the kernel cleanly. I have the PCI address space somewhat figured out so the ethernet work but I don't have the S3 display chip working yet. I can dump the pcmcia space but don't have any support for it yet.