thanks for the tip! I will check it out. In the M100, RAMRST is meant to protect the ram. However, in QUAD one has to back drive RAMRST to essentially put the internal memory on hold.
On Sun, Nov 5, 2017 at 12:06 PM, Atsushi Takahashi <[email protected]> wrote: > 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 > > >
