z80 has plenty of margin - 250ns data valid after pWR* goes hi. I am seeing about 10 - 20 ns but not consistent. Need to figure out how to shorten pWR* or get data to be valid longer. I guess I will be getting intimate with Wilcox book on his S100 state machine. I believe Pontius experienced that is was very marginal. Guess you have been lucky John.
Dave On Saturday, June 28, 2014 9:20:46 PM UTC-5, yoda wrote: > > Hi John > > Yes I think we need to get this resolved quickly before we do another > round of boards. I did find in Wilcox's book on page 331 that the chips > should be schottky devices which would be U38 and U42 which I have replaced > with 74F series - the prop console works but I would not say reliably yet. > I am putting it back on the logic analyzer now. I also notice compared to > that diagram the pWR* path has an extra inverter in it which would cause > and extra 7-10 ns delay which may be stretching pWR* out maybe too far. I > want to compare to Z80 board after I take another snapshot on the analyzer > - I think pWR* is getting delayed too long. The circuit you are thinking > of in the next post is the one that generates A0 from LDS and uses an RC > circuit on one of the legs - that seems to be working ok as the address > lines look solid. I will continue digging and let you know - think we > should delay the 68K board until after you get back. Have a fun vacation > > Dave > > On Saturday, June 28, 2014 6:06:41 PM UTC-5, monahanz wrote: >> >> Dave I have not had a problem with that board with the Propeller Console >> IO board at all. Have not run it with the IDE board. That said I could only >> get about 6MHz out of a 10Hz chip. I know Todd is about to order another >> batch, we should resolve this ASAP >> I'm MIA for two weeks unfortunately >> John >> >> John Monahan ([email protected]) >> On Jun 28, 2014 3:32 PM, "yoda" <[email protected]> wrote: >> >>> Hi >>> >>> Wondering if people have been using the 68K board. I think I have >>> timing issue because pWR* is going HI at the same time the data is being >>> released. You can see this in attached LA capture. I think that is why I >>> am not getting characters from the prop console and probably explains why I >>> have not gotten reliable data from the IDE card either. The dual serial >>> card and memory work just fine. I have tried different clocks as well - >>> this one is at 2MHz so that should not be the issue. Was wondering if >>> someone had seen this and resolved. I will dig through the schematics and >>> the Wilcox book as well. I think once I have this resolved, I can get CP/M >>> 68K going. >>> >>> Thanks in advance >>> >>> Dave >>> >>> >>> -- >>> You received this message because you are subscribed to the Google >>> Groups "N8VEM-S100" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to [email protected]. >>> For more options, visit https://groups.google.com/d/optout. >>> >> -- You received this message because you are subscribed to the Google Groups "N8VEM-S100" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
