> On Apr 27, 2016, at 9:07 AM, e...@e-bbes.com wrote:
>
> Zitat von Paul Koning <paulkon...@comcast.net>:
>
>>
>>> On Apr 27, 2016, at 3:47 AM, Dave Wade <dave.g4...@gmail.com> 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.
paul
