Create a VAX CPU with FPGA?

Paul Koning pkoning at
Fri Mar 4 17:04:13 CST 2005

>>>>> "9000" == 9000 VAX <vax9000 at> writes:

 9000> There are many "soft CPUs" around. I wonder how hard it is to
 9000> create a soft VAX CPU core that can be load into an FPGA. Other
 9000> than to design from scratch, I think it might be easier if we
 9000> grab the VAX-11/780, 750, or 730 schematics, and throw them
 9000> into an FPGA compiler. The 780 was implemented with TTL, the
 9000> 750 with gate array, and 730 with AMD 2901. I think the 730
 9000> scheme might be the easiest to implement with an FPGA.

You'd also need the microcode.  The schematics will only give you the
micro-engine.  The microcode is what turns that into a VAX.

I suppose you could do a VAX in hardwired logic, but that would be
HARD given the instruction set.  A bit easier if you use the minimum
subset, I suppose.


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