yet another pdp-11 in fgpa - test-drb@ccmp.vtda.org

26 Jun 2010

RodSmallwood" <rodsmallwood at btconnect.com>  wrote:
...
  How difficult would it be to extend one of these FGPA
PDP-11's to be put
 on a quad DEC board and be a plug in replacement for say an 11/93 or
 11/94 CPU. (M8981-AA OR 11/91-BA)?

 Rod 
Hi Rod,

possible and feasible, but requires three tasks to be addressed:

1. an adapter board is needed to connect the FPGA development
    boards (holding the FPGA and memory) to the UNIBUS or QBUS.
    Main active part of this adapter board are the bus transceiver
    for UNIBUS or QBUS.
2. The UNIBUS or QBUS bus interface logic can be added to the
    FPGA. Given that the system clock period is small compared
    to typical times of these buses it is quite simple and
    straight forward to implement such a bus interface.
3. the current w11a implementation doesn't support bus masters
    on the I/O bus. DMA transfers from disk/tape devices are
    currently emulated. Next versions of the FPGA implementation
    however will add this functionality.

But keep in mind: the current FPGA implementation isn't tremendously
faster than a J11.

     Walter