Digital (Was RE: Mac "Workgroup Server" (or "network server") hardware & AIX)

Eric Smith spacewar at
Wed Apr 27 21:34:12 CDT 2016

On Wed, Apr 27, 2016 at 7:09 PM, Jon Elson <elson at> wrote:
> Sure.  A VAX 11/780 had a 5 MHz clock!  Would be hard for an emulator to NOT
> beat that!  Later models did run faster, but not vastly faster, due to the
> technology of the time.

I'm not sure what would qualify as "vastly faster", but I take it that
170.9 MHz doesn't?
(also required fewer clocks per instruction than the 11/780)

A well-tuned VAX design in a recent FPGA family (Xilinx 7-series or
newer, or Altera Stratix V or newer) might be able to outperform the
fastest "real" VAX, but perhaps not by a whole lot.  FPGAs are
generally much more efficient at implementing RISC processors, but
it's difficult to get a whole lot more than 200 MHz for the
cost-optimized FPGAs, or 350 MHz for the (expensive)
performance-optimized FPGAs.

I've designed VHDL cores equivalent to microprocessors such as the RCA
1802, National Semiconductor PACE, and DEC/Western Digital LSI-11 (at
the microarchitecture level). I'd like to tackle something more
sophisticated, but it's hard to find enough time.

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