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Re: First new vax in ...30 years? :-)

> On Jul 3, 2021, at 6:14 AM, Anders Magnusson <ragge%tethuvudet.se@localhost> wrote:
> Hi,
> some time ago I ended up in an architectural discussion (risc vs cisc etc...) and started to think about vax.
> Even though the vax is considered the "ultimate cisc" I wondered if its cleanliness and nice instruction set still could be implemented efficient enough.
> Well, the only way to know would be to try to implement it :-)  I had an 15-year-old demo board with a small low-end FPGA (Xilinx XC3S400), so I just had to learn Verilog and try to implement something.  And it just passed EVKAA.EXE:
> >FR00000000 200
> >G
> EVKAA V10.4 Hardcore Instruction Test
> Hit any key to continue
> EVKAA   V10.4 pass # 1(X) done!
> EVKAA   V10.4 pass # 19(X) done!
> EVKAA   V10.4 pass # 32(X) done!
> EVKAA   V10.4 pass # 4B(X) done!
> EVKAA   V10.4 pass # 64(X) done!
> EVKAA   V10.4 pass # 7D(X) done!
> EVKAA   V10.4 pass # 96(X) done!
> EVKAA   V10.4 pass # AF(X) done!
> EVKAA   V10.4 pass # C8(X) done!
> EVKAA   V10.4 pass # E1(X) done!^C


Having an emulation that can pass a serious instruction set diagnostic is a very impressive accomplishment, especially for an instruction set as complicated as the VAX.  I suppose it helps a lot that it is very well documented, in particular in the VAX architecture standard.

The fact that it fits into a "small low-end FPGA" is a nice demonstration of how much technology has advanced. 

The next test is to confirm that it runs VMS.  DEC large operating systems were traditionally used as final system test, since they stress the system beyond what diagnostics do.


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