Dear Steve, I ordered the old QUAD boards from OSH Park but I also purchased one of these LM810M3-4.63/NOPBCT-ND
from Digi-Key in an attempt to address the power on reset issue. It’s just a three pin surface mount chip. I used to have something like that in my 68hc11 boards… Do you think they would help you? It probably takes up less space than a cap, resistor and MOSFET... I haven’t gotten around to building the QUAD yet so I cannot testify to say if the reset circuit helped... -atsushi Begin forwarded message: > From: Stephen Adolph <[email protected]> > Subject: [M100] QUAD update. > Date: November 5, 2017 at 9:36:44 AM EST > To: Model 100 Discussion <[email protected]> > Reply-To: [email protected] > > Letting the list know that I have found a couple of defects with QUAD V4 > which I did 2 years ago. Here's the defects I found. > > 1) I did not protect the bank switching function adequately. The M100 OS > will periodically write to ports 80h, 82h and 83h wrt the DVI. This can > cause V4 QUAD to change banks. > > 2) The power up/power down behaviour wasn't adequately protected, and there > was a chance that RAM could be corrupted and/or banks switched on power > transients. > > 3) I was using the wrong timing to provision banks. > > Not too good. In fact I believe this is the source of the frustrations I was > having integrating QUAD with REX Manager. > > > The good news is that I have prototyped a QUAD V5 which addresses these > defects. The changes: > * I have added a MOSFET based "activity switch" that allows RAM and bank > switch protection on power transients > * I have improved the bank selection circuitry to be robust on power > transients. > * I have changed the bank switching commands to make the mechanism more > robust. > * bank switch state is now preserved during power transients. > > I'll report back on how well these changes work out when I get boards back > and have them tested. > > In the meantime, I've taken QUAD V4 off of OSHPARK. > > cheers > Steve >
