7 Jun
2010
7 Jun
'10
1:45 p.m.
On Jun 6, 2010, at 7:02 AM, Jerome H. Fine wrote:
(a) Without being very accurate, and based on your experience with the PDP-8, how
long do you think that it would take you to implement a PDP-11? Just a rough estimate
in months or years!
um. I already did that. It took a few years, but I only worked on it sporadically. It
currently
boots (in simulation) RT-11, RSTS V4, BSD 2.9 and V6. I have not debugged the split I
& D
but it's there.
If you send me a RK05 image with TSX on it I'll try and boot it in sim.
The last FPGA version I did had no MMU but it did boot RT-11. It had some disk problems
which
I have since corrected. I believe I could synthesize and run the "no mmu"
version pretty quickly.
The mmu version need still needs some work do make 50mhz timing.
(b) About how fast might the FPGA solution be
compared to something like a PDP-11/93?
Again, just a rough estimate like 10 or 20 times as fast.
Well, as I said, the no-mmu version runs at 50MHz. I could improve that. The mmu version
probably
won't run faster, mostly due to the 20ns rams on my fpga board.
Any idea why you did an FPGA implementation of the
PDP-8?
back in the day I spent a lot of time on TSS/8. I wanted to run it again :-) And, I
want
to work on cpu's when I grow up.
I also spent a lot of time on RSTS and TSX, hence the pdp-11.
I know the s/w sims are better, but I like hardware and love running h/w simulations.
-brad
Brad Parker
Heeltoe Consulting
781-483-3101
http://www.heeltoe.com