On 10/24/05, Michael Sokolov <msokolov at ivan.harhan.org> wrote: Aaaauuugggghhh!!!! I say this as a former DEC developer... We made our own Unibus, Qbus, and VAXBI products for years... the mechanical aspects of the VAXBI are a PITA. The logic isn't bad - you just hand over everything to the BIIC and magic occureth. I can't count the number of times my 8200 wouldn't boot because I had to reseat the KDB50 cards. Personally, I'd look at it from the aspect of what sorts of ports one needs rather than trying to implement the underlying bus architecture. One needs an interface for disk and tape (might as well be SCSI); one needs a network interface (or multiples); one usually needs serial ports (though a terminal server can suffice for basic tasks like logging in and attaching serial printers)... so there's no reason not to design a virtual bus inside the FPGA and either drive an external SCSI chip or just absorb that function into the CPU design. While I enjoyed my time working on DEC-compatible peripherals, I think it's important not to lose sight of the fact that at the end of the day, the part that mattered was the part that stuck out into the real world, not the bus it sat on. -ethan