[keywords: unibus, pdp-11, disk controller emulation] If anyone has an interest in low level unibus, I scanned in some screen shots from my simple HP1650 and updated my udisk page. Nothing exotic, just basic register reads, npr & br5. http://www.heeltoe.com/retro/udisk/index.html I finally put the async cpld aside and started debugging the simple synchronous state machine. The sync version works much better and is (as you'd expect) much faster. I have some more debugging to do but basic register i/o and dma work well and the cpu can now easily keep up. I hope to prove out the prototype this summer and do a spin modulo work load. (last week all 3 of my 'real jobs' stalled simultaneously - woo hoo! this week i have a pcb board stuck in customs in boston, so my fun work is getting a time slot or two :-) -brad