replying to A friend had a beowulf cluster of IPXs but all running BSD. I too was very satisfied with the Sun IPX when it was new, particularly with Sun's Answerbook (far better than any other online manual system I used at that time) and programmer's workbench development system. I got to know and like the S-Bus when writing a device driver for an SDLC card. I still remember the phonecall requesting assistance with my device driver. It wouldn't work on the Sun 4m processor. It turns out the processor delays bus writes in order to share the bus with other processors, so I had to add a magic .asm spell to flush the writes. I would've figured that mapping the I/O registers into the memory map would've implied write-thru. -- jeffj