[HECnet] pdp-11/83-84

[Dave McGuire]

On 07/05/2012 09:00 PM, Paul_Koning at Dell.com wrote:

On Jul 5, 2012, at 7:35 PM, Johnny Billquist wrote:

...
Oh, and I saw some additional discussions about the CIS option for the F11. Unless I remember wrong, and understood things wrong, it is not just a simple PROM. It's a coprocessor, which have logic in addition to whatever microcode the coprocessor need.
So no way of just duplicating a PROM to get a CIS.

Not unless someone could dig up the details.   If it *is* just a PROM, even if it's an oddball bipolar model with different interface specs, it should be easy to reproduce that with a small FPGA.   Any reasonable modern FPGA is way faster than a 1980s era bipolar ROM, so modeling the interface timing should be easy.   And level conversions should be doable.

  So a sort of daughterboard?   That's a good idea.

  I'm pretty sure the F11's manuals are out there, but I haven't gone
digging for them.   From that, and possibly even just from the KDF11-Bx
schematics, one should be able to glean the important parts of how to
interface to the microinstruction and microaddress buses.

  Then all we'd need is a copy of the actual code.

                      -Dave

-- 
Dave McGuire, AK4HZ
New Kensington, PA