Digital VAX, Alpha (Was RE: Mac "Workgroup Server" ...

Paul Koning paulkoning at
Wed Apr 27 10:27:04 CDT 2016

> On Apr 27, 2016, at 9:07 AM, emu at wrote:
> Zitat von Paul Koning <paulkoning at>:
>>> On Apr 27, 2016, at 3:47 AM, Dave Wade <dave.g4ugm at> wrote:
>>> ...
>>> Digital is now a fond memory for most. Both VAX and Alpha are no  longer manufactured.
>>> I actually wonder if an FPGA VAX chip could be made that would run  faster than existing real VAXEN. That could perhaps form the basis  of a nice VaxStation...
>> Clearly that's possible given that today's clock speeds are much  higher than those of any VAX, and you could put caches on-chip as  well for additional points.  The difficulty would be to create an  accurate enough implementation.
> If "accurate" means to run VMS or Unix, it shouldn't be to difficult.

You might be surprised.  Getting a PDP-11 FPGA to be accurate enough to run standard operating systems is hard enough (as I found out helping Sytze's "pdp2011" project).  And that's a much simpler CPU than VAX.  In particular, the privileged architecture tends to be critical for getting an OS to boot, and that part tends to be poorly documented (as well as variable from one CPU model to the next).
>> For that matter, by the same reasoning it should be doable (and  quite possibly easier) to build an FPGA Alpha.  Is the Alpha  architecture manual ("SRM") online?
> Is there any demand for it, besides of being fun?

I don't know.  Fun is certainly a good reason for many of us.  There might actually be commercial demand; some people still run production on architectures substantially older than VAX or Alpha.  I don't know if there are any unexpired patents; if not, then implementing a machine from the published documentation seems fine, though running the software might require answering some licensing questions.


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