On Mon, Nov 28, 2016 at 8:22 AM, Brad H <[email protected] > wrote:
> Hey guys, > > > > You might recall a while back I was having issues where I'd have to power > up/power off multiple times before I'd get the 6800 to start up correctly > and give me the SWTBUG prompt. What I did was remove an overwrought > modified RAM board and replaced it with a more basic 4K board set to the > $A000 range. That worked great for a while, but not we're getting back to > the situation where I power up many times and get either ? marks, a string > of 4s, or some other random character. I have to power off and on several > times before I get the $ prompt. > > > > I figured out how to run a proper RAM diagnostic and no errors came back. > I > wasn't sure how to properly test the $A000 board - I assumed I couldn't > let > the test test the address space used by the test program itself, so I set > it > to run from A07F to AFFF (I think I did that right, I set the MSB in A002 > to > A0 and LSB in A003 to 7F, and for the upper limit MSB in A004 to AF and > A005 > to FF). > > > > I'm wondering now if this is really a RAM problem or maybe something else. > I don't think it's the serial card.. I've tried both the MP-C and MP-S and > no change. > > > > I have an NOS MP-B2 motherboard here. The 'check pins' on the molex > connectors for the cards haven't even been cut. I could set that up for > testing although, being totally unused I'm hesitant about altering it. > What > do you think on that? > > > > Brad > > My first question (and pardon me if this was addressed in your earlier thread) is, have you checked the power supply? If possible, use a scope, but even a good DVM will tell you if you're maintaining voltage. And if the filter cap is the original, just replace it - they have a limited lifespan. I bought one from Digi-Key for $19. Hope that helps -- Ian -- Ian S. King, MSIS, MSCS, Ph.D. Candidate The Information School <http://ischool.uw.edu> Dissertation: "Why the Conversation Mattered: Constructing a Sociotechnical Narrative Through a Design Lens Archivist, Voices From the Rwanda Tribunal <http://tribunalvoices.org> Value Sensitive Design Research Lab <http://vsdesign.org> University of Washington There is an old Vulcan saying: "Only Nixon could go to China."
