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Re: Sunday with my SuperBoard II
Posted: Mon May 04, 2015 4:21 pm
by BillO
Update in post 1.
Re: Sunday with my SuperBoard II
Posted: Mon May 04, 2015 8:50 pm
by Jeff
Hi Bill,
I have been reviewing your design along with the schematics of the 610 and 600 board and have been wondering about the DD line. To my (limited) understanding, the DD line is generated on whatever expansion board is plugged in and controls the data direction of the 8T28's on the 600 board. What I don't see in your design is how or where the DD signal is generated. Does it come from the lattice chip? I looked at the PLD code you posted and it doesn't seem to be in there. Could you clarify, please?
Best Regards
/Jeff
Re: Sunday with my SuperBoard II
Posted: Mon May 04, 2015 9:07 pm
by Jeff
Hi Bill,
Please forgive me if this is a stupid question. In your first post you posted this picture:
- Screen Shot 2015-05-04 at 2.01.37 PM.jpg (188.41 KiB) Viewed 23654 times
The 8T28s (U6 and U7) on your Superboard that are used to buffer the data bus are not populated. How did it ever work without these inserted? Did you take the photo before you added those chips?
Again, please forgive the stupid question.
/Jeff
Re: Sunday with my SuperBoard II
Posted: Mon May 04, 2015 9:21 pm
by BillO
No questions are stupid Jeff, just some answers.
I hope to avoid that...
Actually, that picture was taken just between having jumpers connecting the boards data lines to the CPU's directly and putting the 8T28s in.
Since then I have tried it both ways and both ways produce exactly the same error pattern.
As to the DD line, on that original rendition of the prototype board it was just connected to the /OE line. However, as I may have mentioned, that did not allow for OR-tying. I have since added a 2N7000 to pull the DD line low. The code has changed somewhat too as I added the ability to move the 32K chip's address to begin at 0000. However, none of that has made any difference to the errors I'm seeing. I'll try to update all the files tomorrow.
Re: Sunday with my SuperBoard II
Posted: Tue May 05, 2015 5:33 pm
by BillO
Code has been updated to most recent.
Re: Sunday with my SuperBoard II
Posted: Wed Jun 24, 2015 5:29 pm
by BillO
Update in post 1.
Re: Sunday with my SuperBoard II
Posted: Thu Jul 16, 2015 7:31 pm
by BillO
The boards are in and the RAM only board is ready to go!
See the update in post 1 for further details.
Re: Sunday with my SuperBoard II
Posted: Fri Jul 17, 2015 12:14 am
by Steve Gray
Looks great! I just ordered two 32k boards!
Steve
Re: Sunday with my SuperBoard II
Posted: Sat Jul 18, 2015 2:10 am
by MK14HAK
Awesome work Bill.
Does the ROM socket allow Ram to be fitted there for 48K or can you use say 8K on board plus the 40K ?
Please, one if each for starters.
Mike
Re: Sunday with my SuperBoard II
Posted: Sat Jul 18, 2015 2:02 pm
by Jeff
Bill, do you have a part number for the headers with long pins?