rewriting legacy OS for new iron

[Zane H. Healy]

Greg Ewing:
> Lyle Bickley <lbickley at bickleywest.com>:
> 
> > I thinks its a LOT easier (and more fun) to simply run it on real
> > DEC hardware - or if you can't create that environment - run it on
> > Intel via the SIMH or ERSATZ emulators.
> 
> Maybe run an emulator directly on the hardware, without any other OS
> in the way? That would be the next best thing to implementing the OS
> on the bare metal.
> 
> Sometimes I think it might be fun to build an emulator based on an
> FPGA. Then you wouldn't have any other instruction set in the way,
> either. :-)
> 
> Has anyone out there done that?

For an emulator the route to go is a dedicated box, with as lean of an OS
installation as is needed to boot the computer and run the Emulator.  That
is if you're looking for optimum performance (and if you are, running on a
dual processor box would be good as well).

As for the FPGA route, there are commercial PDP-11 CPU boards out there that
use FPGA's for the CPU.  Oddly enough, while hobbyists have done several DEC
CPU's in FPGA's (including two different PDP-10 projects), no one to my 
knowledge has done a PDP-11.

I for one would love to see a FPGA Hobbyist implementation of a PDP-11 that
includes memory, SLU's and a disk controller, and could either be a SBC, or
go onto a Q-Bus board.

		Zane