Unibus disk controller with modern storage

Fritz Mueller fritzm at fritzm.org
Wed Oct 19 20:24:25 CDT 2016

On Oct 19, 2016 6:48 PM, "shadoooo" <shadoooo at gmail.com> wrote
> Hello,
> I read several posts about Unibus disk interfaces and emulation.
> One of my retrocomputing dream is to design an Unibus universal board,
> probably based on FPGA because of precise timing requirements,
> to emulate one or more disk/tape interfaces, and possibly something more.
> The real storage could be based on SD card, so very easy to be moved
> to a PC for imaging and data transfer.
> Probably a low level emulation would be quite easy, while a more complex
> solution (MSCP) could be more difficult.
> The board itself wouldn't be cheap at all, because PCB would be big,
> and because FPGA aren't cheap either.
> Probably it would be anyway cheaper than an MSCP-SCSI, and it would be far
> more
> flexible.

A good way to go on this might be just a small paddle card with Unibus 
drivers, level conversion, and some shift-register chains, which could 
then be interfaced easily to any number of off-the-shelf FPGA 
prototyping boards (the latter having the advantage of being quite 
cheap, with many integrated peripherals like ethernet, SD slots, USB 
serial, etc. and having tool chain support out of the box).

I've seen a few projects started like this out in the wilds, but none 
seem to have made it past the debug stage.

It would be super useful -- you could emulate all sorts of peripherals 
as well as memory, or you could configure it as a Unibus analyzer, or 
emulate a CPU to debug peripherals.


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