[HECnet] PDP-11/70 on FPGA

[Brian Hechinger]

On Tue, Aug 10, 2010 at 06:50:32AM -0400, Paul Koning wrote:

http://opencores.org/project,w11
Think that can run RSX/RSTS?
I'll have to take a look... a second reason to get an FPGA eval board...

It only runs on two boards, but at $100 for one, it's not a bad price, really.

Yes, it should run most software just fine.

Excellent.

I have just a few gripes with this implementation. If they matter to you
or not is for you to decide:

1) No FPP. I think this is important, others might disagree.

I get the feeling that's something he'll be adding.   Does the lack of FPP affect
me currently?   Probably not, but of course it would be nice to have.

2) Small disks. Only RK05 for now, and no plans for MSCP at all. While
future massbus is cool, by todays standards, fixed size, rather small
disks, are not that useful.

Yes, this I can agree with, most definitely.

Non-MSCP disks can be done in logic; MSCP has always been implemented as firmware running on the storage controller.   Presumably you'd want to do likewise here.   That's certainly possible, with the help of an embedded processor inside the FPGA.   Then you'd have to implement the MSCP firmware, which is a fair chunk of code.   (I don't suppose anyone has the UDA50 firmware available?   Then all you'd need is an FPGA model of the hardware, which would be easy by comparison.)

I *think* I've got a UDA50 laying around (or know someone who does), what would
be required to extract the firmware from it?

3) Backend very dependant on some host machine with OS. I guess it helps
to make it doable faster, but for me, the really nice thing would be
something like USB interface to mass storage, which looks like MSCP from
the PDP-11 side. That would be *really* cool.

By far the easiest storage interface is IDE (ATA); is that still around?   Well, it is, in CompactFlash cards... which would do nicely actually.

Yes, I agree, the backend server bothers me a bit as well.   I've love to have
something I could plug a CF card and an ethernet cable into and be done with
it.

That all being said, I'm sure this guy isn't done and who knows, send him your
suggestions, he might be up for it. :-D

-brian
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